Page last updated July 17, 2008



Common Lower unit diagram

Outboard Water Pump Repair

Just the Impeller or you can replace all gaskets

Page 2. Take your time and don't force anything.









Same as above. Make sure you remove remnants of old gaskets from ALL PARTS.

You can try to lightly sand parts to make sure they are flat. You can glue a piece of sandpaper onto an old piece of smooth thick particle board (some other types may warp) and slide the piece on top, lightly. This is only to smooth parts due to light warping, marring so that new gaskets make a better seal. Clean non metal parts with a solvent (not carb cleaner).

28 Impeller housing. Clean off and inspect impeller as well as housing. Check for any surface that may catch the impeller as it spins and try to smooth out.
29 Here are the old gaskets and these are what was needed for this job, your needs may differ. I left the drive shaft o-rings alone.


To replace, just go in reverse order. Make sure you use some sort of gasket sealer, especially in the first gasket going back in. It seems as if the seal will be bad, so I placed a small amount of RTV gasket maker on the lower spots to create a better seal with the real gasket. It works and I don't know if it was needed, but it looked like a seal was not possible without the RTV.

These are old engines and a good quality seal may appear at first, but don't be surprised or dissapointed if you notice that oil still leaks a short time later. These are old engines and time, heat and pressure tend to warp parts. You can minimize the leak by trying to straighten parts by sanding down until the part is smooth. You can study parts and see if you should also place some gasket sealant / maker. I applied some gasket maker because I noticed the seal was going to be bad. A little attention to detail goes a long way. It does not leak anymore.

If you happen to have a "gearless" lower unit, it is possible to replace fluid with grease. It has to be a special grease (brand to come soon, need to find it). The grease, obviously, comes out slower. The great thing about this is if the lower unit leaks a lot, instead of having to refill the lower unit after each trip, you can simply regrease and it wont be as much, but it has to be a gearless lower unit.

After this job, It was late and so I let sit overnight. It is best to give the pieces some time to cure, especially if you used gasket sealant. It may or may need time, but always best to give it time (follow manufacturers recommendations).

I started up the next day and there was no oil in barrel. This was a big improvement for me, since I saw a small trail of oil as I iinitially tested boat and motor. I did not want to be polluting the lake.

This was not a very difficult task and can be done by most. The tricky part is assembly of the lower unit back onto the motor. Make sure you place gear shifter is in forward gear (different motors may be require another gear). In order for the reverse lock to function, the gear has to be in forward and the plastic reverse lock on lower unit must be placed so that it is just about ot hit the highest part of the lock. When you place into neutral, it will rise onto the plane and be at the highest part. This will of course not allow you to raise the engine while in neutral, but I found that the reverse lock would not function unless I installed while in forward gear.

Also, make sure the water tube is in its proper place. You can guide it with a screw driver slowly before you completley push the lower assembly up. If you look at the water impeller housing in first few photos, you can see raised area where water tube goes into.

Test the gears. Place in neutral, prop should spin freely; forward gear should only spin in one direction and prop should slice through; reverse, prop should also only go in one direction and opposite of slicing motion.

If they don't work as they should remove again and check your assembly. You may need another set of hands or a screwdriver to push the gear shift or the water tube where it needs to be.

These water pumps have a small hole at the top of the lower unit. It is on the black water pump base housing and it drains into the exhaust port.. I am guessing to relieve pressure but it also spills some oil out when you initially run it. Be careful with this leak; don't assume the oil film is a leak. If it stops after a few minutes of running, you should be fine. Again, better to use a rubbermaid can to test for oil leak.

More pictures to come.

Have FUN!!!!


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