Considering adding stop leak to power-trim for fading issue

[Dave1027]

1988 Mercury 100HP. Trim works fine except it will slowly lower by itself. This means that while cruising I have to hit the trim up every 5 minutes or so because it trims in slowly by itself.

I was thinking it's not worth it to me to spend a lot on this for a rebuild. I'd rather keep hitting the trim than blow the dough on it. How about adding some ATF stop leak to it? I don't think it can hurt and may swell the seals just enough to help the issue or fix it entirely. Who knows?

How should I add it? Do a complete fluid drain and refill? Siphon out some from the fill tube and add? Will that get the stop leak circulated into the system well enough or will it only sit on top?

 

[Chris1956]

The seals in that PTT unit are probably all O-rings. I am not sure the stop leak will affect it positively. It very likely will screw up the control valve with it's springs and small passages. Why not price a repair kit? It should be under $50.

 

[TD_Maker]

Problem is that the repair kits for that motor are obsolete. Also, it is very hard to get anyone to work on them for that reason. Your "Leak Down" issue is not uncommon. The ATF repair fluid does nothing except swell the seals in automobile transmissions; unfortunately, outboards have rubber O Rings. You mat do more harm than good. I would look for a used T&T unit to fit the motor.

 

[Mi duckdown]

What Chris Posted.

 

[Barnacle_Bill]

I use to have a 1983 Merc 150 that had a slow leak in the T&T. I added some TransX to the fluid until I got the time to fix it properly. Anyway I had forgot that I added that stuff and about 3 or 4 years later I sold the boat and it was still holding good. Actually I had forgot all about it until later.

 

[Chris1956]

if you can gw a spec for the Oring sizes, you should be able to get replacements in an Oring collection.

 

[Chris1956]

That is "Get a Spec"

 

[Boss Hawg]

I did the TransX thing like Barnacle-Bill. Its holding a little longer every time I use it- I did only add maybe 2 ounces tho-