ohnson, Evinrude, OMC, outboard motor, outboard motor repair, 9.9, 15 hp, year of manufacture, powerhead, piston, water pump, carburetor, long shaft, 15 hp conversion, sailmaster

Motors Covered Here:  This section will cover all the 2 stroke 9.9 motors but keep in mind that there are slight differences between the pre 93's  which are minimal but the procedures are the same, just possible different parts configuration.  The pre-93 blocks used heads with the spark plugs on the RH side, while the post 93s had the spark plugs on the LH side of the head.   The upper motor mounts are also different between the pre & post, but in the same location & do the same thing.

The post 93s are sometimes referred to by OMC mechanics as large block 9.9s.  This whole series of 2 stroke motors are looked at by knowledgeable boaters as being nearly bullet-proof.

Does it really Need to be Rebuilt ?:  What is wrong ?  If there appears a problem, this problem should be diagnosed before jumping into a rebuild.  Why does it not start/run right?  What is the compression?  Is there any spark?  What about the fuel system? Does it rattle (piston wear) when running slow?  All these need to be checked out & sometimes just the little things are the culprit.  If the spark plugs are fouling a lot, are they the right ones, & is the fuel mixture right, what about possible debris in the carburetor or are it's adjustments right?  If any of the above can not be remedied, then a rebuild, or at least a re-ring & new seals may be considered.  

But will it be cost effective, even if you do the repairs yourself?  Of course if there happens to be a blown piston, then you have no choice than to rebuild, other than scrap the motor.   Another option is to watch e-Bay.  However in the past recent years, these parts appear to be drying up somewhat.  Occasionally you will find supposedly running powerheads for a decent price off motors that had a bad lower unit.  You will be amazed at the demand for these old parts & with the pre 93's being made for 18 years, there are lots of them out there being parted out & also others in search of parts.  But be careful as what the seller advertises, as most do not know what they have or what years will interchange.   Do not buy it unless the seller can identify the year & that it may be compatible with yours.

 My repair time to re-ring a motor is 2 hours to remove the powerhead from the mid-section, 2 more hours to tear the powerhead apart, hone the cylinders & replace the parts, plus another 2 hours to re-assemble everything.  Then unless I run into an unexpected situation, it usually takes another half hour or so to get it running right.   So you can see a possible repair cost near $500 just for labor if it is taken to a marine mechanic who gets $75 an hour.

In any case if there is any question as to condition of a motor, it is a good idea to pull the head & the LH side bypass cover.  With both of these off, you can at least take a peek inside for possible clues as to the condition of your motor.   This will give you some idea as to what direction you need to go if repairs are needed.   If the cylinder is scored & the pistons/rings are scored/damaged it is pretty sure thing you will not get it running with any reliability by just reassembling it.

In photo below of a motor that came from Texas, you can see all the salt corrosion in the water jackets between the cylinder walls & the outer block walls.  This corrosion was so hard that a hand drill motor & 1/8" drill was used to rout out the RH side only of the lower cylinder in this photo.   With the accumulation of this corrosion laying at the bottom.  The whole LH side water jackets are solid corrosion.  The cylinders are rusty, lower ring stuck on #2 piston, compression was better than expected however.

It is hard to understand why this motor was not flushed after usage in saltwater, as it is a 1994 that has a factory flush plug made into the upper top of the water jacket cover & the word "FLUSH" near it.   Probably lack of knowledge or just plain LAZINESS.  The pile of white dust at the bottom of the photo is dried salt/aluminum that came from the water jacket & only from the RH lower cylinder area.

The motor below  as described above.

Removal of the Powerhead:  If I give the worst case scenario on some of these situations, don't think that it may be normal, only that I am trying to pre-warn you of what MAY happen & give you possibilities of how to proceed from there.

If it comes time that you need to get into the powerhead, you should probably remove most all of the bolt on parts off before you unbolt the powerhead from the exhaust housing.  Here is where you need the illustrated manual or a darned good memory as to where things came from.   Best is to use a digital camera & take many photos of even the wiring, carburetor linkage, fuel line routing, how the timing plate is attached, & a lot more before & during disassembly. 

If any of the bolts appear frozen, you might try to tap the bolt head with a hammer, this sometimes slightly breaks a bond between the bolt & the plate it holds.

I have found it best to have used margarine buckets or similar plastic dishes to put the screws, bolts or pins & washers into.  If you have 3 or 4 of these, you can then place the parts into different ones pertaining to the different parts of the motor.  Then remove the shift lever cotter pin & cross pin, allowing the clevis to be disconnected from the shift lever.  Next, take the fuel line loose from the fuel pump.

Another thing you may need to do is to cut the kill switch wire that goes into the rubber coupler.  Later units have a bullet type quick connector on this wire.  The kill switch ground wire (usually a yellow with black spiral stripe, while the older ones may be just black) can be unbolted from the powerhead.

Remove the lower unit, water pump & driveshaft.  If this lower unit will not come off, see the paragraph relating to this below the photo.

If after you have all the bolts loose & it will not budge, what is holding is probably the gasket between the powerhead & the midsection. 

I have had a couple that did not want to come apart.   One, I used a heavy rubber or plastic mallet & judiciously hit the high sides of the block trying to move it sideways.   The other I ground down a large screwdriver to near a knife edge & lifted away the foam rubber grommet that is showing that covers the front juncture of the powerhead/lower unit/ lower pan.  Drive this screwdriver point INTO the gasket.  Do it again on the other side.  You might be able to now use a large screwdriver on one side & try to pry it down with both, pushing the powerhead up & apart.  You should be able to break the bond this way, once it starts you may be able to work around to the rear.  When you get it off, you may have to file off any burrs you have created.

This is about the only location where you can apply external leverage if the gasket is stuck tight to the 2 surfaces.

Can Not Remove the Lower Unit From the Powerhead:  The lower unit will have to be removed anyway as it is a whole lot easier to line the driveshaft splines up into the crankshaft if the powerhead is bolted on first in reassembly.   Use the same procedure as replacing the water pump.  This will allow the lower unit to drop down about ½” till it is stopped by the shifting rod.  If it does not drop this amount, move the shifting lever, & if still no movement, you can pretty well be assured that the driveshaft is frozen into the crankshaft, or you missed a couple of bolts.   But, with this lower unit loose, you may then be able to take a large rubber mallet or block of wood & try to pound on the stiffener angled brace on the rear that goes to the cavitation plate, maybe even the prop-shaft gear housing, (or anyplace that you will not break).   This will normally allow it to drop down enough to remove the shifting rod coupler bolt & the unit will then fall off.   

On rare occasions, if the above does not do it, pound hard enough or pry on the lower unit (evenly) to break the top of the water pump (all that holds the driveshaft in other than the splines when totally assembled is the impeller key).  You might have to make wooden wedges & force a few in around the opening so you put pressure evenly on the seized spline.  Try to move the whole lower down, allowing the driveshaft to be pulled out of the impeller & thru the top of the now broken plastic water pump housing.  The driveshaft floats on splines on both ends, one in the crankshaft & the other in the pinion gear in the gearcase.

If this works, now the driveshaft can then be pulled up & out with the powerhead so you can at least get to the splines & free the shaft.  The old water pump is just pot metal on the early motors or plastic if the motor is a later version. 

Remove the cotter pin holding the shift lever yoke to the motor. Also remove the overboard water indicator hose.

You will need to do the same basic removal of the exhaust housing from the gear case as required to replace the water pump impeller.  Once the gear case unit is off, then you will need to remove the 6 bolts that hold the powerhead to the exhaust housing.  Next is removing the 3 motor mount bolts.  One is under the manual starter unit near the carburetor, with the other 2 in the rear, both right & left sides

After removing these bolts, the powerhead should be free, if not see the section above. 

Suggestion #2:    A suggestion is that you get (4) 1/4" X 20 machine bolts the same length as the ones you just removed & screw them partly back into the 4 front & rear powerhead mounting holes.  These will then be screwed into the bottom of the block.  Leave them protruding slightly & get a heavy punch & tap on each, trying to raise the block & break the bond of the gasket & the extension.  Using new bolts will save the stainless ones that came out if the ones inserted do get bent.   I have also tried to pry from under the intake manifold.   Or use a strong screwdriver & go in from the rear under the foam rubber seal between the rear cowling & try to wedge it between the block plate & the mid-section.

Other problems:    It can very well be tight, being stuck by the gasket which seems to have an adhesive on the sides.  But also the lower crankshaft seal extension, (actual name, the crankshaft head & seal assembly) has the lower section of it a slide fit into a mating hole of the mid section.  This can become bound up by corrosion if the last mechanic did not put a smear of waterproof chassis grease on it before reassembly. 

The extension's lower end positioned just above it's mating hole when assembled shown on a post 93 model

If the powerhead does come loose but only rotates slightly, you can not rotate it sideways very far, as there is the inner exhaust tube & the water pump outlet pipe both attached into the bottom of the powerhead & keep it from rotating.

Once the powerhead is loose & all the parts are off, pull it up & off.  There will be an squareish exhaust tube about 1 1/2" across if the motor is the older 9.9.  If a 15 hp after about 1987 there will be a rounded exhaust tube.  Also a ½” copper water supply tube will be bolted onto the bottom part of the powerhead.  Unbolt this block & remove the attached parts.

Disassemble the Powerhead:  First you will have to remove the 4 outer screw that hold the armature plate with the charge coil & timing sensor coil.  Next remove the 4 screws that hold the retainer plate. Now you can remove the crankcase head, which is a aluminum plate with a circular tapered tube that us held on by 3 bolts to the underside of the powerhead & which the driveshaft does up into connecting it to the powerhead.  Remove the head.  Next remove the intake manifold, the reed valve plate and the bolts under it for the front half of the powerhead.  

Now the powerhead should come apart at the center or crankshaft area.  It will have an alignment dowel on one side, which may have to be tapped out.  If the two halves do not want to come apart, readily, then with a plastic mallet, tap the crankshaft forward or rearward.

Once you have it apart, you now can get to the connecting rod bearing caps.  Loosen the Allen head cap bolts & take the caps off.  There should be a mark on these so that they have to go back the same way they came off. If not it is best to file 1 mark on one side of the top rod, either right or left on both the cap & the rod so you know where it goes back.  Do the same only file 2 marks on the bottom cap & rod.  When you take the roller bearings & cages out, place them, or mark them so they will go back on the same rod they came off of.

On this motor the rod bearings are also the same as the center main bearing.  The bottom main bearings are regular ball bearing type bearing & is pressed onto the crankshaft.  The rod & center main bearings were changed in 1984.  The top main bearing is a caged roller unit.  Regular automotive type seals are used top & bottom.

The rings used are 2 per piston, with the top one tapered from the outside upward & inward.   Before removal of the old rings, check to see that some may be stuck in the piston ring groove.  If so break one of the rings & use it as a groove cleaner to remove any carbon.  We are making an assumption here that with the motor this far torn down that you are going to re-ring it, so you need to hone the cylinder walls enough to score them, helping the new rings to seat properly.  If you do not have a hone, then it is suggested that you use emery cloth of about 80 grit & sand the cylinders in a circular motion to break the glaze & give the new rings something to help seat them in.

Remove all the old gaskets & clean the areas where the gaskets were.  It is suggested that you do not try to scrimp on costs here by trying to reuse the old gaskets.  For one, most all of them, other than possibly the head gasket will not be salvageable, & for the price of a couple of dollars each it is best to replace them because in this manner you can get the corrosion cleaned out of the water jacket passages & be assured that you have done a good job.  What you can not see under a gasket may well come back to bite you after you get it all back together.   Check for any carbon buildup on the pistons & head remove it by wire brushing them. 

Reassemble the Powerhead:  Before you reinstall the rings, it is best to reinstall the rod caps on their rods with the pre-marked sides together & check for internal concentricity.  Run your finger nail around inside where the 2 join.   Is there a catch indicating a miss-match, tap the cap until it does match.  Tighten the cap down to almost completely tight & check again.  If you are satisfied that it is true, then check the outside mating edges.   If they are off, file them true.   What you are trying to do here is assure that the insides are true & then match the outsides.  Once you have these assembled on the crankshaft, you can not really tell if the insides are true because you can only see the outsides.  The reason they may not match even though they came off together, is that possibly they may have gotten squished on the initial assembly.  Here you are just going the extra mile to assure that your repair job is 100%.

Check the new rings into the respective cylinders to ensure that there is sufficient end gap so that when they get hot when the motor is running that when they expand that they brake or score the cylinder walls.  If they fit the specs, then install them on the pistons.  The pistons will usually have a small pin in the ring grooves.   The ring will have the ends thinner to match the pin, which keeps the ring from rotating & requiring the proper positioning of the ring, & later having the end get at one of the openings of the cylinder port, thereby giving a chance for it to break or score the cylinder wall.   Lightly oil the pistons & insert into the block using a ring compressor, with the rod pointing forward to allow the piston to be seated below the cylinder opening.  

Install the crankshaft bearings, place the crankshaft in place on the block, & assemble the rod bearings, making note of the previous alignment markings.  You may find that an extra roller bearing will be included than actually needed.  I was sure I replaced all of them in one rod, but when I found an extra the next day, I tore the whole thing apart again just to be sure.   Place the rod bearings in the rod, install the rod cap & lightly tighten the rod bolts.  At about 98% tight, run your fingernail on the outside edges of the rod/cap juncture to feel if they are aligned, if not tap the cap & check again.  These caps need to be 100% true on the inside so the rod bearings have a smooth surface to ride on.

Check the mating surfaces of both halves of the block, file any burrs if necessary.   Place the aluminum mating gasket cement on the two halves & assemble them.  Replace all the bolts holding the two halves together, being sure to remember the one under the intake manifold.

Install the seals & the crankcase head.  Check out the reed valve unit, & be sure that these valves are not rusty or bent  & lay flat against the plate.  Replace this unit & the other covers etc.   It is not required to use regular gasket sealer as these gaskets adhere quite well.   Be sure that you have the right manifold gaskets in the proper place.  IF you happen to place the front gasket on the rear of the reed valve plate, this gasket has a smaller opening for the valves.  It will hold the reed valves closed & you WILL NOT get the engine to run more than even a pop or two.

Bad Block:  Occasionally you may run into a bad block for one reason or the other.  It could be a broken ring that scored a cylinder wall badly & it is not practical to rebore it.   It could also be a very worn & oversized cylinder holes, & again not practical to rebore.  It could even be a blown piston with a hole out the side that can not be welded.   Most of these blocks are pretty much interchangeable if within the the close years of manufacture.

Concerting an early points type ignition block to a electronic ignition unit can be done, IF ALL the electronics, like the timing base, flywheel, coils, & powerpack are also changed.   The head will have to have a bracket made to secure the powerpack to.  However this conversion is not really worth it unless you happen to have two motors that you can swap parts from / or to.

I have recently found one combination that will work IF  observations &  modifications are looked at closely.  I had a 1987 15hp that had a badly worn set of cylinders.   I also had in my pile of parts, a block off a 1982 that had been recovered from a watery grave & the cylinders were slightly rusted.  The water outlet & exhaust parts were a match, (not so on some earlier blocks in the pile).  I honed it out & surprisingly the cylinders came out good enough to warrant the change.  This motor I was trying to repair had the newer cable throttle system.  Upon reassembly I was having problems getting the timing base to rotate full requirement.  Plus the recoil starter could not be bolted down tightly without binding & the neutral safety anti-start ratchet would not function.

What I found was that, I had utilized the same vertical control shaft plastic shaft clamps that came off the 87.   The older motors using the gear type linkage used a sheet metal clamp & the new plastic clamps on the old block pushed this shaft 1/4" forward when using the old block.   I also found that the base for this clamp was changed on the 87 by machining it at an angle as compared to just let the boss extend to the rear.  This was for clearance for the new type cable connector to the timing plate.

There appears to be about 3 variations in these 74 - 92 blocks.  Note the differences in the early 74 style on the left with the later 87 block water outlet passage indicated by the blue arrows.   I suspect this would not be critical as both use the same gasket which has a hole directing the water out, but that it may create a "Hot Spot".  JB Weld & a Dremel tool would possibly fix this situation if you think it need be the same, but this is the final water passage, and the gasket is the same, so no real deal.

Old block (probably a 77ish) shown upside down with full boss for vertical shaft pivot	Newer block (87+) shown upside down & with part of the boss beveled off for clearance

Also note on this photo below on left, that the older metal clamp had to replace the newer plastic clamps, as indicated below by the red arrows. 
 

Here the vertical shaft new style clamp needs to be replaced as not enough room to fit recoil starter	Here the old style clamp has been installed on the new parts, but old block giving room for starter

The red arrow below shows the metal removed for clearance of the ball & socket assembly on the end of the cable attached to the timing plate.

Modified block boss to fit new type throttle cable system

Exhaust Housings:   Prior to 1981 OMC Both the 9.9 & the 15 hp exhaust housings were the same, after that the 15hp was different.  In the pictures shown below, the 9.9 & early 15 hp is on the Left.  It's tube is a rectangular unit, while the later 15 hp unit is basically a somewhat tuned 2 stroke exhaust.   They both utilize the same water supply tube, (not shown) but that goes in the front or lower RH holes of the RH pictures.  The 9.9 housing being longer, mounts against & is sealed by a rubber ring the inner section of the lower unit.  The 15 hp housing stops short, why I can't imagine.  The short copper tube on the rear of the 15 hp housing is for the warm, used water to exit the motor at a lower location apparently since the whole inner housing is now somewhat pressurized when being used & the motor lower unit buried in water.

Then in about 1987 another exhaust housing was brought out, or so the parts list show, however I have never actually seen one. This mystical one is a short rectangular unit & is used for both the 9.9 & the 15 hp motors.  My reasoning for the 87 date is that the 86 parts list still shows the old housings, & the 1990 list has the newer one.  This motor underwent many changes in 87 as to thermostat, fuel pump, twist grip throttle, etc. but my 87 15 hp uses the same as in the right of the LH photo below.

Old 9.9 & 15 hp exhaust housings on LH, with new combo 9.9/15 housing on RH side	Same 9.9 & 15 hp exhaust housings, top view

Stripped Spark Plug Threads:  Occasionally you may encounter this situation.  If it is a 1974 - 1992 motor, you can probably find a used on on e-Bay.   One caution here is the 74-76 heads will fit the 77-92 motors but will not have the mounting lugs/holes for the powerpack.   For the post 93  heads since there are less of them out there, so finding a used one will be about be impossible. 

The method of repairing a stripped thread is to drill out the old threads & install a new threaded bushing using the Heli-Coil method.   The regular Heli-Coil unit uses a tap that consists of a dual threaded tap, one threading into the old threads & behind that are flutes that cut & re-tap to oversize all at the same time.   The one problem with this method is that if you can not get the pilot tap to enter the damaged threads straight, you are in trouble.  Hence the photo below.

A Heli-Coil kit for this size thread is $40.00 so unless you may need to use it on other motors, it might be best to take the head to a automotive machine shop.   If you plan on doing it yourself, no real problem, just follow the directions.  For the 74-92 motors where the plugs are at a single angle with the head, it is not a real problem.  But you have to get it right the first time, if it gets started cross-threaded, when finished the spark plug gasket will not seat properly against the head because on these Heli-Coil taps, the pilot needs to thread into the existing threaded hole, so you need enough good threads for the tap to follow.  This is not normally the case after the old threads are stripped. 

However if you happen to be working on a post 93 motor where the spark plugs set at a compound angle, (both to the side & upward) it is hard to be sure that the tap is in proper alignment.  This is also why it is a challenge to even start the spark plug correctly because of the dual angles & the hole is below the top of the lower cowling making for visual observation hard.

Shown below is a photo of a compound vise set up in a milling machine so the tap goes in at the same angle that the original spark plug threads.   This is not really the facilities that the average shade tree mechanic has available to him.   In setting this up, the tap's pilot threads were screwed into the good hole & the compound vise rotated in two angled directions until the tap was level & perpendicular to the mill's table, then the table was moved to align the quill to the bad hole.  Next the tap was just started in the bad hole with a quill center point into the small center hole of the tap & leveled in all directions by moving the table as required.   Once the tap was leveled to the hole, pressure was exerted by the quill & at the same time the tap was turned inward, cutting oversize threads so the Heli-Coil insert could be inserted.

A fixture set up for proper alignment to re-tap a spark plug thread in a 1994 head

Parts & Gaskets Most Likely Needed:  If the motor is in need of repair, the most common problem will probably be the rings need replacing. The rod & main bearings will usually good.  Seals should probably be replaced whenever the unit is torn apart.   And a new gasket set is probably in order.  If you order a gasket set, check for the components, as if it is an OMC set, usually the bottom crankshaft seal comes with the set.   If it is an aftermarket set the seal does not come with the set.   A gasket set will also include, carburetor to manifold gasket, fuel pump base plate gasket & fuel filter gasket among others.  The headgasket for the 74-92 motors are different than the post 93 series because of the larger piston.  The earlier gasket will fit, but the first time you pull the starter rope, the top of the pistons will hit the edges of the gasket ruining it.

The likelihood of of salvaging the manifold, sideplate & bypass cover gaskets is very minimal, however probably 1/2 the time.  And the headaches involved by reassembling the motor & getting a badly running engine that needs to be torn down to just replace these gaskets are something that you do not need, especially since the cost of these simple gaskets are minimal.   So if at all possible try to use new gaskets especially on the reed valve plate & the intake manifold.

I have seen the headgasket come off clean enough that it can be reused if applying a light coating of a good gasket cement.   This is not recommended, unless the head is true & no visible problems.  However the increase in the price of this gasket has brought many to try the cement trick.

You will also need a sealer designed to seal the two halves of the block together that does not utilize a gasket, but only the two mating aluminum parts.  About the only time you will need some gasket sealer is if you are trying to reuse an old head gasket.  It is however best to wait until you have it all disassembled before you order what you think you may need.  

Leaf Valves & Plate:  Here is something that is usually overlooked.   If the leaf valve plate is stuck to the block by the gasket & you try to pry it off with a screwdriver, you may well bend it or at least upset a but in the aluminum plate. You will need to be sure the plate is flat, otherwise the leaf valves will not close when the engine is back together & any slight leakage will be detrimental.    Do not rely on the manifold to straighten this plate when bolted down.  File off any burrs you created.  Check the plate for straightness, if bent use a large heavy metal plate & after removing the leaf valves & stops, try to straighten it with a plastic mallet.   When you get it as close as possible, then get a piece of glass & course valve grinding compound & lap the plate so it is flat at least where the leafs lay.   Clean the compound off, reinstall the leaf valves & see that they lay tight to the plate.  The manual says do not try to bend them, but I see no reason that you could not if you do so only so that they JUST close when in the assembly condition.  The manual also does not say anything about the height of the valve stops.  I have taken this dimension from the top of the stop to the plate off existing operating motors as shown below.

If these valves are not in correct contact, by not being installed right, or the plate bent, or not tight under the manifold by burrs, the motor will not run right, as idle, burn lots of fuel & leave oily residue on the water.

Leaf valve plate assembly	A side view of the leaf valve stop

 

Repaint Before Final Reassembly:  You can purchase OMC original paint at about $8 a can, or Krylon brand which is available in about any hardware or automotive store, in about any color you want, it may not match exactly the original color however, but it is less than 1/2 the price.  You may be able to get by with one can if you do not use a lot of it on the inside cowling or on the powerhead.  I initially used the Krylon brand as I like the idea of being able to touch up paint scratches if the need arises.  Krylon's Ivory Gloss #1504, is very close to the standard white that most of  many of these later motors were painted with.  The one drawback using a non-original paint is that it may not be as resistant to gasoline or oily film on the water as the factory type.  Krylon does make a Crystal Clear Gloss #1301 spray paint that would be a good for a top coat, but I have not found it to be effective in deterring oily residue grime from getting into the paint.

I have found with the OMC paint, do not try to do thick coverage or it MAY wrinkle.  Do many thin coats.   In a repaint job from years before that had been painted with Krylon, it did not adhere to the original paint job well & required a complete stripping before the OMC  repaint,  in the long run, OMC paint may be the best for the exposed parts of the motor.  

I am trying a automotive spray wax that goes on after the motor is washed & then wiped dry.  Hopefully this will be just enough to help preserve it & keep any oily residue from the exhaust to stain it. 

The 1974 Johnson OD green color was changed to white in 1977.

If you plan on replacing the decals, you will probably not be able to find any OMC originals available earlier than about 1996.  Price is about $50 for these original replacements.  If you purchase these newer decals, you will have to cut them to fit, as the newer side decals sets lower than you might think.  This is because the motors have a upper cowling that the seam is more horizontal instead of at an angle on the pre 93's.  This changes the position of the decals if used on an older cowling.  You will have to trim some off the front bottom at an angle of these side decals to get the lettering horizontally positioned.  And you will also have to trim the bottom rear decal to be somewhat close to a decent position.  Lay them out & tape them on the cowling before you install them.   You will not get a decal for the front where the control knobs are on these newer decals as there are none used on these later models.  

There has recently became available on e-Bay aftermarket vinyl decals that are generic for this series of motors at a price of about $13.00 + a set.    These generic ones are quite good, a close coloration to the originals, but do not match any specific year, have the "Sea Horse"  & appear to be laser cut.  They appear to be made for many Johnson & Evinrude motors from 6 to 90hp.   See picture on the Part 1 article.  The lady supplying these die laser decals has recently expanded her line, but with a price increase for the larger models.

When installing any of these, it is best to lightly pencil mark the cowling with the top & front locations of the edges of the decal.  These will be VERY sticky, so BE SURE where you want it to do.  When you peel off the backing, start on one corner, but just let it lightly stick, if it appears correct, allow it to lay it in a rolling motion, by peeling more of the backing off.  You will be trying to get the top parallel to the top edge of the cowling, with the rest laying down while NOT allowing any air bubbles to get under it.  IF you are lucky you MAY be able to let one end lightly lay in position, then if the rest appears to lay OK, roll it with your hand working out any air bubbles &  pull the first up, re-setting it & rolling it back forward again without any bubbles.  If you do get a few bubbles under the decal, take a needle & prick the decal, then work the air out the pricked hole.

If you decide to repaint the cowling for the pre 93 motors & the rubber motor seal is OK, you can pry it away from the fiberglas or plastic depending on the year, placing matchsticks between the rubber & the fiberglas to allow for a better paint job to go under the seal.  This original rubber seal is stapled onto the fiberglas.  If you need to replace the seal (about $40.00) after repainting, to reinstall it instead of trying to staple it, just use a latex adhesive & many old spring type clothes pins until the adhesive dries.

The later motors after about 1987 had the power head, flywheel & prop painted black.

Removal & Replacement of the Upper Motor Mount 74-92:  With the motor in normal operation the movement between the motor swivel base unit & the actual pivoting part of the motor should be minimal.  The upper thrust mounts are a rubber anti-vibration connection between the pivot shaft unit & the swivel/clamp base.  If the rubber mounts are broken / unbonded from their attachments there will normally be more forward/aft movement than lateral movement simply because of the way the mounts are made.  Usually only the upper mounts go bad & the lower rubber mounts are OK.

These upper motor mount usually does not require any attention.  However I have two motors that I purchased used, that had been used with a clamp around the housing that was used for a trolling tie bar to an I/O unit.  The problem was that whoever attached it to the motor put the clamp around the lower housing AND the driveshaft housing.  This put so much pressure on the rubber mount that over time it disintegrated & left a lot of wobble forward & back.   This may not be the only reason these upper mounts go bad.

These motors use 2, one on each side.  Both sides use the same mount as they are made symmetrical & one is rotated 180 degrees of the other.

Upper thrust mount attachment screws

There are 2 screws from the outside of the housing, with only one showing until you remove the lower cowling pan & they / (it is shown above) may well be frozen into the internal bracket.   They may have to be broken loose by the aid of an impact driver set.  When you strip the Phillips heads, you may have to set it up in a sturdy drill press or milling machine & drill the screw head off.  All you need is to get thru the head, as the threads are usually loose in the inner bracket, but the screw body is corroded in the exhaust housing.  Then you may be able to drive it in to take it apart & then twist out the remaining screw threads.   Replace these 4 1/4" screws with stainless & coat the threads with an anti-corrosion compound. 

If, when you are doing a powerhead repair,  while the motor is this far torn down it may be best to at least check this rubber mount.   This repair requires the complete power head be removed to get to this upper mount.   The twisted off or milled off 1/4" bolts shown below are what was left of the above indicated bolts.

My Homemade Replacement Upper Motor Mount:  In the photo on the right below is my thrust mount conversion.  Since I can not bond the rubber like the original was, I use a tight fitting friction compressed fit to hold it in place.  I use the standard motor mount rubber (factory nomenclature "grommet support" #316354) of which there are 3 mounting the powerhead to the base cowling, as shown at the top 2 items, & remove the center steel bushing.  Now I take it to a standard medium grit stone wheeled grinder & modify the outer edges of the rubber beveled as shown, but not removing any from the center. 

Now I lathe turn a 9/16" aluminum rod down to 3/8" & drill a 1/4" hole all the way thru.  The placement of the shoulder & the groove are so that the steel bushing that was removed from the motor mount is now centered on the new aluminum, while making the overall length the same as the old center bushing of the original mount.  Next I cut a narrow shallow groove for a 3/8" E-Clip so that it encapsulates the rubber at the distance of the old steel bushing.

Shown in the LH photo below are the new rubber mount parts.  The rubber can be collapsed on one side into the hole enough so that the rubber can be forced into the mount's original base.  The bullet shaped dual diameter piece on the far right is simply a installation tool to be able to push the new bushing into the rubber.  Lubricate the rubber center, bushing & the tool with soapy water.  Insert the tool into the bushing & push the bushing into the rubber that has been installed & center aligned in the base.  The new bushing should be installed so that the forward thrust from the prop pushes away from the E-Clip, or with the shoulder to the front.   Now install the E-Clip holding the rubber centered on the bushing.

The damaged old rubber mount is shown at the bottom of the photo for illustration purposes.

Shown below are  the upper thrust mounts for the pre 93 motors.  The left & bottom ones show the bonded rubber center torn loose or gone.  The one on the right is a new one.  The top one is the center rubber mount.	Here is my alternate thrust mount conversion

 

Dimensions of Conversion parts

There may be some confusion here as in the picture below,  it shows the 2 mount locations where the mount assemblies are & a thrust mount in the middle.  These mounts are essentially an aluminum block that is secured into the sides of the housing by (2) 1/4" screws for each that come in from the outside.  Bonded into these blocks are rubber bushings that have a steel sleeve also bonded to the hole thru the rubber.  Here you may be able to improvise by taking a thick rubber & freezing it, drilling a hole for the bushing, then turning the outside down & then glue the rubber to the sleeve with Gorilla glue.  The reason for freezing the rubber is so that you can machine it.  Last Bombardier replacement cost is $38.20 EACH. 

The upper thrust mount  for motors is a rectangular piece of hard rubber is 1/2" X 21/32" X 1 3/16" in size & is clamped between a bar inside the exhaust upper housing & two fingers that  protrude rearward thru a set of rubber grommets that seal & slightly support things.  There are four 1/4" Philips headed screws protruding on each side of the outer upper exhaust housing, (the upper ones are tucked up under the lower powerhead cowling), that hold the internal brackets that this mount assembly is attached to.  

If the motor was used in salt water a lot, the drilled out studs may well be frozen into the base.  To break them free, heat the up the aluminum base with a torch & spray some penetrating oil around the studs as it cools.  If the rubber is still intact, you can not use the torch as you will ruin the rubber bond.

There is also a rubber seal or grommet that usually needs to be replaced at the same time as the upper mount.  This grommet acts as a seal for some exhaust noise & oily residue from the inner exhaust system.   It  goes across  in front of the housing with bellows thru the housing to then be bound against the mounts on the inside of the housing.   In the left picture below, this seal is on the left of the thrust mounts the arrows point to.  The seals are of rubber & like a short bellows to allow for flexing.  You can see a white space between 2 of the bellows.  This white is the 1/4" screws showing, so this particular set of seals also needs replacing.

In the above LH photo the 2 bolts that are backed out about an inch, many times you will twist off inside the steering bracket boss when removal is tried.  If this happens you will then need to remove the exhaust housing from the steering bracket (as the twisted off threads will now be in the steering bracket boss).  This removal is no big deal as you simply remove the lower mount cover & the lower rubber mounting blocks will fall out & the two housings will come apart. This bolt does not need to go into the steering boss as deep as it was originally.  I have found that if it does break, it will be at the threads.  Just retap the hole down to the broken bolt with the next size (5/16") & put in a shorter bolt.  You will have to drill the center metal upper mount tube out to accept the 5/16" bolt however

There are also 2 lower rubber lateral mounts that complete the mounting unit.  These side mounts normally do not require any replacement, however the front lower mount can get deformed & become a sloppy fit.

Reinstall the Powerhead:   Basically reverse order in your re-assembly.  As the motors get newer, they start cramming parts in places that were not meant to be, especially when it comes to an electric start model.  Here the wires, & hoses have to lay in the exact right position, or things will not be able to fit.   Install all the bolt on parts except the manual recoil starter, before you try to assemble the power head unit to the lower cowling & exhaust housing.  Be sure that the lower crankshaft seal is in place & the exhaust housing is bolted in place to the bottom of the powerhead.  Next, you should be sure the large rubber grommet that acts as a seal between the lower cowling & the exhaust housing is it's proper n place on the exhaust housing.

 Run a new 1/4" neoprene fuel line from the coupler on the LH side, down inside the LH motor mount, around behind & on the right side near where it will go forward & connect to the fuel pump. This fuel line HAS TO GO outside the RH rear motor mount to give clearance to bolt these motor mounts down.  If the motor is a manual start, the fuel line will attach to the rotatable fuel filter cover with the hose fitting pointing rearward.  If it is a electric start model the filter cover will need to be pointing forward & down & the fuel line needs to be longer to accommodate this move.  The reason is the electric start rectifier sits in the location where it interferes with the fuel line.  Bolt the 3 motor mount bolts in with the washers both above & below the rubber bushings.

The best way I have found to install the shift linkage rod is to assemble it to the shift lever linkage & install the cotter pin in the pivot pin, then as you slide things together with the rod down in the housing, you can see this rod hitting the grommet near the bottom.  There is enough room here to use a screwdriver to reach in & position it so it will go down into the grommet & farther down. You may however have fun aligning the water pump tube so that it goes into it's allocated hole.   

It is easier at this point to also be sure that the twist grip mid section throttle gears are aligned & the shaft is in it's proper relationship with the mating holes as indicated by the  grooves & mating bumps for their respective locations. 

Start the 6 bolts that hold the powerhead to the exhaust housing, once they are started & everything looks like it is OK the snug them tight.  Reassemble all the external parts.  Replace the lower unit (gear case) as when you would have replaced the water pump impeller.

Break in the Rebuilt Motor:  Once started, it might be wise to increase the oil to gas ratio by about double for the first 3-4 hours of run time.  The reason for this is that there may be more friction due to tighter bearings & piston rings, which create heat.  The extra oil will help keep it from seizing up.  Bolt the motor onto the in side of a 55 gallon barrel with water filled high enough to cover the cavitation plate, & run it.  Do not just run it at an idle, but speed it up to a fast RPM occasionally.  This is also a good time to get the carburetor set for it's proper setting at an idle, as you want the motor running at it's best before you get on the water.

To make one of these run barrels, use a 55 gallon steel fuel/oil barrel, cut part of the top out, but leave about 1/3 still attached.  Cut back about 5" along the sides of this remaining top.  Now bend this 5" section down into the barrel to form a downward lip.  This will allow you to rev up the engine for short periods of time while in gear without blowing the water up & out of the barrel, as this baffle diverts the prop water back down into the barrel.  

One thing to check, is that if you leave the barrel set outside from year to year with water in it, you should dump it out occasionally, as any debris in the water can plug up the water intake screens & make you think the water pump is bad when you later run a motor.

The lower shifting rod can become pitted at the O-Ring seal area.  If this is the case, either replace it, or since it is stainless steel, you can silver solder up the pitting & then lathe turn or bandsand & back down to close to the original size & polish it.  Is does no good to rebuild this unit & then allow a minor spot to be a leakage point.  To replace the O-Ring seal for this rod if you do not want to totally disassemble the unit, you will need a slide hammer type puller.  Take a 1/4" All-Thread about 20" long, slightly taper one end, & grind off the corners of a 1/4" nut so that it will just go inside the hole in the lower unit that this shifting rod goes into.  Push the pointed end of All-Thread down thru the shifting rod hole in the gearcase housing.  Using a flexible spring loaded pick-up tools, position the ground off nut inside the gearcase housing & thread the All-Thread into this nut.  Slide the slide hammer handle onto the All-Thread, & screw another nut onto the upper end for the slide hammer to hit against. Now it works best to tip the unit upside down, & using the slide hammer, pull the washer, O-Ring & brass bushing from the gearcase.  If the unit is disassembled, just put a nut on the underside of the all-thread in thru the open gearcase, & you can use a steering wheel puller to pull the seal & bronze guide.

Clean them up, & in all probability the lower washer may get deformed in this pulling operation.  Hammer it flat again.  Remove the old O-Ring from inside the brass guide, install the new one & place these parts back in place.  Use a 1/2" rod to drive all these parts back down into the gearcase housing.

Another important thing to inspect is the water intake screen that is in this unit.  If the screens have been damaged, which can be observed from the outside, it should also be replaced, as if large intake holes are there, then debris can get sucked into the water pump & farther up into & possibly plug the internal water passages.  This is simply a small plastic basket that is tapered on 4 sides & has perforation holes on 2 sides which acts as a filter for larger debris.  The screen is inserted into a blind hole of the intake cavity.  The old screen is removed by simply using a long screwdriver to break it apart enough to remove the pieces.  The new one is inserted by making a wooden insertion tool the shape of the internal part of it & tapping it down into place.

Copyright © 2004-2009 LeeRoy Wisner  All Rights Reserved

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Originally started 11-2004, Last Updated 07-06 2009
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