Trim OK but no tilt: Force 90 hp 1991

[BarryK3]

Hi all,

Trim/tilt was working perfectly at the harbor the other day but when I got home the trim worked but no upward movement beyond maximum trim. I could manually move the motor up and down to full tilt with NO resistance either direction. The switches and electric motor for the trim pump work fine. The motor sounds normal. Trim works full range of motion up and down, though it seems SLOWER than before.

I filled the reservoir: no change.

I went through the troubleshooting instructions in the factory manual. When the line to the bottom of the tilt cylinder is capped, the motor drops about 1/2 way and the holds with a very slow leak down. It is VERY spongy. It stops a few inches above the upper limit of trim. When I cap the line to the bottom of the trim cylinder and plug the hole on the pump, I get the same results: motor drops about 1/2 way to a spongy stop.

Last summer, I replaced the small o-rings in the check valves in the pump (Briggs and Stratton lawnmower part trick) and had NO leak down after that. So, I took apart the check valves to inspect them: everything seems fine. I cleaned and checked the shuttle valve and blew out the small passages in the pump with compressed air. The pump and electric motor seem fine.

I also see a small oil leak around the tilt piston shaft, at the top of the cylinder.

So I guess I will buy the rebuild kit and spanner wrench and take apart the cylinders.

It is a mystery to me exactly what part broke. It was a sudden failure.

Happy New Year!
Barry

 

[jerryjerry05]

Read the top 3-4 posts.
There are good instructions for diagnosis and repair.


You took apart the check valves? you put in new seals?
Take it apart and see if an o-ring failed?

A small leak at the tilt shouldn't be too much of a problem.

 

[BarryK3]

Thanks Jerry,

Yes, I took apart both of the check valves in the pump and all of the o-rings seem to be OK. I also swapped the front and rear check valves when I reinstalled them and it had no effect on the problem.

Did you mean to attach a link to the posts you mentioned?

I will disassemble both of the cylinders next to see what the o-rings look like.

Take care,
Barry

 

[jerryjerry05]

No link, just read the posts and find the T@T repair.
It has a lot of good info on repairs.

If you took the vales apart you should have replaced the seals.
https://forums.iboats.com/filedata/fetch?id=7105526&d=1432665255
This shows the seal that's probably leaking.

http://forums.iboats.com/forum/engi...e-hints-on-the-t-t-repairing-the-relief-valve

None of the repairs show any thing for the tilt shock.
Usually the seal on the shaft if it's leaking the seal is pretty hard if not impossible to find.

Look around on e-bay and salvage sites for a new/used shock.

Sent u a PM.

 

[BarryK3]

I replaced the seals on the check valves a few months ago. I inspected them the other day and they are still fine.

I ordered the "RRitt" o-ring kit for the cylinders, a 3/16" spanner wrench (for the shock and tilt cylinder) and a 1/4" 12 point socket (for the trim cylinder bolts). I'll start putting Kroil on the parts while I await delivery.

I should have rebuilt the entire thing before I installed it last year!! Used parts.

I'm having trouble viewing PMs today, maybe a website issue?

Thanks!
Barry

 

[BarryK3]

I took apart the cylinders today. I soaked everything with Deep Creep and Kroil for a few hours beforehand. Everything came apart easily.

The trim cylinder is fine. The 1/4" 12 point socket (Craftsman) worked great for bolt removal. No broken bolts.

I recommend this tool to remove the top of the tilt cylinder:

3/16" Pin Diameter up to 2" Max Adjustable Face Spanner Wrench, Williams USA #482

It is a very sturdy wrench and fit perfectly. I was able to take it apart while the bottom of the cylinder was still attached to the transom.

The problem is a broken check valve in the tilt cylinder piston. It is the valve that relieves pressure when the engine is fully tilted up and the piston hits the stop. The retainer had come out and the ball and spring were loose above the piston. So there was a wide open passage for oil through the piston. Therefore no tilt at all.

So the dilemma is what to do now. Used cylinders on Ebay are expensive and the piston is not available as a new part. Unfortunately the small cross-shaped retainer is missing since the small parts fell out when I removed the piston (I was not expecting loose parts). I think I will try to make one out of a small washer and either press it in or tack weld it. I'm not sure if JB Weld would be a good idea or not. It looks like the factory method was to hammer the metal above the retainer in 4 spots to create dimples that pushed the metal out slightly above the retainer. Maybe I could try this with a punch?

Barry