Replace trim pump motor or whole thing?

I got the trim pump (1978 prestolite) hooked back up in my boat today and gave it a go. I don't have the solenoids replaced yet and one is bad, so I was just jumping the hot leads from the trim pump motor to the battery to see if it worked correctly. It was very erratic in operation... would run for a second or two, then stop, then would start again and stop and do nothing. The original wire leads from the motor are extremely corroded and green in color with the insulation nearly completely gone. I'm supposing a wire short somewhere in the naked wires, probably where they go into the grommet into the motor housing. The few times the motor did run, it did move one of the trim rams (why not both? because they aren't hooked to the outdrive? no load?), so the pump seems to work fine when the motor will turn it.

I don't want to have to mess with this again for a while, so I either want to replace the pump motor or the whole darn thing. I've seen Don recommend just replacing the whole unit with the newer style with the plastic tank. I see several of these with the plastic tank on ebay. Will they work with my older setup? Am I correct that they mount to the deck rather than the motor like mine? I shouldn't have a problem with that.

I thought I could save the old pump, but guess not. Don't want any problems on the water. Ebay has a couple of the old prestolite pumps like mine, but who knows their condition being that they are so old.

I'm looking at: Mercruiser Trim Pump Late Model
and
Volvo, Mercruiser, OMC Power Trim Pump

What do you guys think? As long as it pumps fluid, it should work, right?

Re: Replace trim pump motor or whole thing?

From your description, I think you just need to open the motor, replace the 2 leads with the same size wire and reassemble. The trim pump motor is used only intermittently, should last for years.

When it does run, fluid will flow to the ram with the least resistance, if not connected to an outdrive.

Re: Replace trim pump motor or whole thing?

Back about 8 month ago or more, I took the motor apart and cleaned it all up because at that time it wasn't running at all. I cleaned it all up (the brushes & armature looked fine although I didn't test it) and reassembled everything and it ran fine, but it didn't have the load of the pump and the cylinders on it. Anyways, I don't remember how the leads connected to the inside. Would I have to solder the new wires on? I'm going to look at the manual and see if it shows how they connect in there.

Re: Replace trim pump motor or whole thing?

I'd swap the pump, but then again,,, I have the pump off my old boat sitting on the shelf

I have a new style pump on a pre-Alpha drive and the swap was pretty straight forward. I used a new style manifold and new style lines, so everything from the pump to the manifold is like an Alpha 1 GenII. The trim ram hoses were the same size, old manifold and new manifold, so these were not changed.

If all your hoses are in good condition, you will need to get some adapters that downsize the fittings on the pump to the manifold hoses. Well, that's if you are going to swap over to a new style pump.

Re: Replace trim pump motor or whole thing?

dccordell said:

.....I don't remember how the leads connected to the inside. ....

Click to expand...

Open it up, have a look. Nothing to lose if you're considering replacing it.

Re: Replace trim pump motor or whole thing?

I started to take it apart yesterday, but ran out of time after I got the motor off the reservoir. I'll try to get back over there and have a look.

If I just replace the whole thing (some decent prices on ebay), even though they list them for the alpha and other drives, it should work either way right? Maybe have to adapt the lines like fishrdan said.

Also, do the newer style pumps use the two-solenoid setup? So the wiring should be the same as my old pump if so...

Thanks for the replies yall

Re: Replace trim pump motor or whole thing?

I had a trim motor do the same thing to the letter... I fooled with it a lot and never could get it to work right.. So I replaced it with one of those cheapo ebay units... Been working great since...
good luck

Re: Replace trim pump motor or whole thing?

Any issues with the line fittings not being the same size? Think I read somewhere that they had to be adapted to the new style pumps.

Re: Replace trim pump motor or whole thing?

well I just replaced the moter... The PO had put the pump on years ago.. It wasn't factory.. A Volvo replacement.. Lots of folks on here run that dreded 470 so someone should know what to do... Maybe repost and change the title to have that its a 470

Re: Replace trim pump motor or whole thing?

Just letting you guys know that I went with a pump from ebay. It was from an earlier 470 (but newer than mine), but had the stand that bolted to the deck, instead of the bracket to mount it to the motor like mine originally had. I was able to swap the brackets so the new pump mounted to my motor just like the old one did. I got it installed the other day, filled er up, and temporarily wired it up and it works great up and down. Hope this problem is taken care of for a while... thanks for the help everybody!