Force T&T leaking down 856X8A

[buddhapi]

I've been working on a 1988 85hp Force motor with a T&T that keeps bleeding down with no exterior leaks. I did put the new Tecumseh/B&S rubber needle valves seats in today, but still the same outcome. T&T is settling....sometimes all the way, but sometimes it'll settle like 2 inches and then hold....for the most part. I've bled all the lines to make sure fluid came out and kept the reservoir full. this is the dual tilt shocks and the big hex trim in the lower center. COULD the trim piston be leaking internally tot he point of me losing pressure? when the customer brought the boat, 2 of the 5 bolt heads in the tilt were broken off and the trim was leaking. BUT, he did say it was settling last year already, before the trim leak and broken bolts.

 

[SkiDad]

check out this thread - you can make a few caps/plugs to isolate whether it's the trip cylinder or tilt cylinder.

http://forums.iboats.com/forum/engi...outboards/659768-88-force-85hp-trim-drop-help

 

[buddhapi]

come to think of it. I don't think the trim piston moves in and out... like it should?

 

[buddhapi]

Thanks. I'll check that thread out!

 

[jerryjerry05]

Usually if the t/t leaks all the way down the pump is the problem.
In fact 99% of the time it's the pump.
I have found in 40yr only 1 trim cylinder bad.
But do the tests. You might be a 1%er.

Some of the guys on here have luck rebuilding them.
They might be interested in doing yours.
In fact I'd like to get a couple rebuilt too.

 

[Frank Acampora]

If the bolt heads were broken, it is almost a sure bet that the cap has cocked and the trim piston is cocked and jammed inside the cylinder. Remove the hex cap and try to pull the cylinder itself. It will most likely be corroded into the aluminum. So, then take a hammer and smack the livin beejeesus out of the trim piston to try and move it down. Otherwise use a press to push it out. Once you get it to move, remove it and check the condition of the O-Ring. Replace if necessary. Replace the cylinder O-ring seals in the cap and body. Then, check the piston O-ring in the hex cap and check the wiper rings. Replace if necessary. Replace the hex cap after installing the piston. IF at all possible, get five new aircraft grade 12 point stainless bolts to replace the old ones. The old ones have been stressed and even if the caps are good they could fail in the future.

I could not get those bolts so I settled for stainless allen head cap screws. I have used the TNT a couple of times with no problems but I really don't know how long the bolts will last so I can not recommend them. After all, the original engineers specified a stronger, more costly bolt for a reason.

Good luck getting the broken bolts out. Use plenty of "our friend heat" and even then it is a good bet that you will need to drill and tap at least one. Use a cobalt steel bit and drill slowly with a lot of pressure.

I have had a couple of tilt cylinders leak at the piston O-ring. They start out drifting down and as the O-ring progressively gets destroyed they will no longer lift. If you raise them and let go they will bang down.

Once you remove the tilt cylinder from the engine: If you don't have the special; wrench, make a spanner and remove the cap. The piston and rod will come right out of the cylinder. Check for a scuffed, cut, or broken O-ring and replace if necessary.

All in all it is a miserable, time consuming job and you will probably need to charge more than the system is worth. You would be better off discussing with the customer the possibility of buying a used, functioning unit. Even then, there is a likelihood that it will take a lot of work just getting the old one off the engine.