tilt trim pump rebuild

specs: 1988 3.0L Mercruiser, Oildyne plastic reservoir tank

long story short:
I got a bunch of water in my tilt trim reservoir. Fluid was very milky, slightly tan. I noticed this after my tilt/trim got slow then quit. I removed the pump assembly, removed reservoir, then removed pump. The pump shaft was very hard to turn. I was about to order a new pump (cheapest I could find: $100+) then decided I'd take the pump apart and hopefully get it to work enough to pump out the old fluid so that my new pump doesn't get messed up also.

Pump was very basic two gear pump. Removed the stuck shaft, lubed with ATF+4, and reinstalled. Pump worked great to flush the old fluid out, and is still working after tilting up and down 20+ times. Another note: there was only one filter instead of two on the pump and I kept it that way.

SO the question is: How long do I have before this pump gives up? Or is the pump only sometimes not serviceable despite what the manual says?

Re: tilt trim pump rebuild

In theory if the bearings arent flatspotted you should be good to go. I think the fact its moving a semi lubricated fluid around again is a good sign its going to keep working!

Re: tilt trim pump rebuild

YeboGogo said:

In theory if the bearings arent flatspotted you should be good to go. I think the fact its moving a semi lubricated fluid around again is a good sign its going to keep working!

Click to expand...

there are no bearings in the pump. The shafts just spin on inside of the pump manifold. (does that make any sense? I should have taken pictures) The pump is just a machined piece, contains two ball bearings (for one way valves I suppose), two gears solidly attached to pins/dowels which spin in holes in the pump body.

one shaft was stuck pretty good in the pump body, obviously causing my problem. My guess is from over heating and expanding due to pumping thick chocolate soup. Once released and lubed it spun with no effort.

I suppose the shaft hole could have flat spotted, or worn, which is why I wonder how long it will last. The pump seemed pretty solid and well engineered, my guess it will last forever, or at least thats what I'm hoping.

Re: tilt trim pump rebuild

If there is a shaft there is a bushing/bearing or impending failure!

I think your good to go! Nice save!

Re: tilt trim pump rebuild

You should be fine. They state not serviceable because if you let it go too far (ruin it) there is really nothing to them and they must be replaced. Seems you saved it just in time..... Now go boating!!