Rebuild kit for tilt/trim???

maverick974

Petty Officer 2nd Class
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Jun 26, 2009
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122
I have a 1984 Force engine. 85 horse. The tilt/trim bleeds down. Sometimes quickly, sometimes not so quickly. It bleeds down on both trim and tilt.
I'm reasonably sure it's the pump and not any of the rams. I just installed it a few weeks ago.
When I purchased my boat it had power tilt only. I found a complete unit with power trim and power tilt from a shop in the next town but the electric motor was bad. Between the two I was able to put together a good tilt/trim unit and it worked perfectly when I got it installed. I took the boat out a few times and the tilt/trim worked perfectly. No bleed down at all. I could put the engine in reverse and the tilt ram would hold the engine in place.
One day I was putting the boat in the water. I apparently didn't back the trailer back as far as I normally do so the boat was stuck on the trailer a little bit so I put the engine in reverse, gave it a little more throttle and got it off the trailer but the engine suddenly popped up while doing that.
Ever since then, the hydraulics bleed down. I've been doing a lot of research and I'm pretty sure it's the pump and not the rams.
So my questions is pretty simple.
Can a guy with reasonable mechanic skills rebuild a pump and if so, where would I, could I get a rebuild kit. Or are there parts available for other stuff that will work?
From the diagrams I can find, there are only a few seals, o-rings, ballbearings and springs. Could it be that hard to rebuild???
Thanks for any help you can offer.
 
Last edited:

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Rebuild kit for tilt/trim???

you either broke a check valve in valve body, have rust in your tilt ram, or blew out piston ring. I doubt piston ring because the pressure is way higher in forward than reverse. If you did not see any water or rust color in fluid while piecing it together then probably not tilt bypass valve either.

so here's what you do.
get a 3/16" brake union and 3/16" plug from NAPA auto parts.
lift engine all the way up and block it into place.
disconnect front side tubing from pump (goes to bottom of tilt)
cap off end of tube
remove blocking and see if engine drops
if engine stays up it is valve body, if engine drops it is ram
 

maverick974

Petty Officer 2nd Class
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Jun 26, 2009
Messages
122
Re: Rebuild kit for tilt/trim???

I figured that if it leaks down on both the trim ram AND the power ram, that it would probably be the pump but I know nothing about these units so I'll check the rams as you say.
In either case, are there rebuild kits available for the rams and/or the pump?
Are there any parts (o-rings, seals, valves or ??) that are compatible from some other application that I can get locally? A/C compressors, auto parts, etc......
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Rebuild kit for tilt/trim???

Both rams are connected. If either ram fails then both fail. However, trim takes a lot more fluid so it will sink down much slower than tilt for same size of leak.
 

maverick974

Petty Officer 2nd Class
Joined
Jun 26, 2009
Messages
122
Re: Rebuild kit for tilt/trim???

That's exactly what it's doing. It bleeds down on both rams with the tilt ram bleeding much faster.
Sounds like I should rebuild the rams first????
If that's the case, are there just 0-rings that I need to replace?
I do have a spare tilt ram that is identical. I guess I should take that apart and see if I can rebuild that first. Can't screw up the system that way if I mess up that ram.
So where would I look for the seals and such for the tilt ram??
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Rebuild kit for tilt/trim???

I would not expect a 1984 ram to fail yet unless there was water in oil. I would expect both your motor and valve body to fail any day now. The manual should have some test procedures where you can positively identify whether it is ram or valve body. My bet would be on valve body.
 

maverick974

Petty Officer 2nd Class
Joined
Jun 26, 2009
Messages
122
Re: Rebuild kit for tilt/trim???

you either broke a check valve in valve body, have rust in your tilt ram, or blew out piston ring. I doubt piston ring because the pressure is way higher in forward than reverse. If you did not see any water or rust color in fluid while piecing it together then probably not tilt bypass valve either.

so here's what you do.
get a 3/16" brake union and 3/16" plug from NAPA auto parts.
lift engine all the way up and block it into place.
disconnect front side tubing from pump (goes to bottom of tilt)
cap off end of tube
remove blocking and see if engine drops
if engine stays up it is valve body, if engine drops it is ram

Ok, I tested it as you said and the rams are holding. No bleed down at all with the tilt tube capped. So apparently the valve body is the problem.
Are there any rebuild kits available??? If not, would it be possible to replace/repair the valve, seal, or checkvalve that is the problem?
 

maverick974

Petty Officer 2nd Class
Joined
Jun 26, 2009
Messages
122
Re: Rebuild kit for tilt/trim???

This is strange. Now that I've tested it and put it back together, it seems to be holding.
Could there have been some grit or something stuck in a valve that would allow it to leak down????
Perhaps I should drain the fluid, clean out the system and refill???? And if so, should I use oil or trans fluid????
 

SSTKO81

Petty Officer 1st Class
Joined
Jun 1, 2009
Messages
341
Re: Rebuild kit for tilt/trim???

I'm having very similar problems with my 81 merc. Did you find a way to fix the problem? Find a rebuild kit? My pump will raise the trim with help but the motor just spins when I try to pull it down. Hope you can help me, thanks.
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Rebuild kit for tilt/trim???

I'm having very similar problems with my 81 merc. Did you find a way to fix the problem? Find a rebuild kit? My pump will raise the trim with help but the motor just spins when I try to pull it down. Hope you can help me, thanks.

odd problem ... gravity should pull engine down. Unless you mean that if you push down on prop then tilt just spins without lifting. In which case it could be blown out piston ring or pump (or both). How long you figure on keeping boat? If long time then get full overhaul and don't mess with it for another 30 years. If only keeping a few more years, then try pump rebuild. Rams have large diameter seals and usually go over 30 years if you don't use any fluid with additives.

BTW - red is always a bad choice in fluid. Maybe you can pick out the right ATF with no additives but you are still inviting mistakes in future. Chances are not so good that the average mechanic can find ATF without additives or will take the time to hunt it down for your engine. Hydraulic oil is best. Find somebody with a million dollar backhoe machine and use the same fluid they use.
 
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