1984 115 hp mercury inline 6 Trim problems.

[Curtis W.U.]

I have a 1984 mercury 115 2cyl inline 6 outboard with a trim system mounted out side boat.
I replaced the pump last year before I got a service manual for it (the pump motor assembly was bad had water in electrical motor and was rusty. Pump part was clean.). So, I used mercury trim oil in it when I went back what came out was not transmission fluid.
After about one year of not using it I was having problems with it lifting like it had air in system. Then it went down and would not raise. I went to the manual, and it says to use transmission fluid. What was used originally was it looked like 10w-30 oil but I went back with mercury trim oil.
Now I am confused lol. I think the problem is it just got low of oil but I have no leaks that I can see. I also think the manual raise/lower might be leaking by. New manual bypass screw in valve cost 27$ don't want to replace it if it is not bad. I have been told to use 10w-30 synthetic oil. But I am skeptical about using that.
what are your opinions about this?

 

[jimmbo]

I had that exact same engine, and its PT system got water in it and quit too. However it was under warranty. I recall the Owners Manual said to use AFT or Power Steering Fluid. Engine Oil was used in the older Pump-inside-the-Boat PT Systems

 

[Chris1956]

A 1984 engine could have the PTT pump and reservoir in the boat or between the transom clamps. The older PTT system (pump/reservoir in the boat) could use 5W-30 motor oil or ATF. I would determine what you have and keep using it.

The newer units (between the transom clamps) use Dextron ATF of the stuff from Mercury.

If she is low on fluid, there is a leak. The water can wash the fluid away.

 

[jimmbo]

1983 was the last year for the Old Power Trim system on the Inline 6. All 84 Inline 6s had the new External System