Power trim not working

[JoshOnt]

Seeing as it is winter I have been trying to figure out how to solve my power trim issue. It does not stay up on land like it should nor in the water. I had to keep trimming up to keep it from diving the bow down. I dealt with it for the two times I took it out after I bought it. I am not sure if it needs a rebuild or where to start. I did go over the whole thing though and look for leaks and I could not find one. Where do I start looking/ trying before I take it to a shop. Mind you I am not mechanically savy and lack many tools past the basic ones.

 

[Frank Acampora]

Well, Josh, a little more info would really help. For example Engine and outdrive or outboard brand.

That said, most trim units whether inboard or outboard use a motor and pump and by far most of the problems are with the check valves in the pump. SO: Specifically, that is the first place to check.

 

[JoshOnt]

Well, Josh, a little more info would really help. For example Engine and outdrive or outboard brand.

That said, most trim units whether inboard or outboard use a motor and pump and by far most of the problems are with the check valves in the pump. SO: Specifically, that is the first place to check.

Motor is a 1977 Mercury 850 and where would the check values likely be located?

 

[Starcraft5834]

" It does not stay up on land like it should nor in the water."

what does this mean? you trim the motor all the way up and it moves down on it's own? . if it sags down on its own, the seals holding the pressure are failing. look at your line connections from the trim motor to the fittings on the rams. there's fluid leaking someplace, or perhaps your out of fluid?

 

[Chris1956]

In your particular motor, the Teflon seals in the twin PTT pistons can leak. The control valve could also leak, but the former is more likely, based upon my experience with that unit.

Rebuild kits may be available, you will need to look for them. A special tool is needed to install the piston(with the Teflon seal) into the cylinder of the PTT unit.

 

[JoshOnt]

In your particular motor, the Teflon seals in the twin PTT pistons can leak. The control valve could also leak, but the former is more likely, based upon my experience with that unit.

Rebuild kits may be available, you will need to look for them. A special tool is needed to install the piston(with the Teflon seal) into the cylinder of the PTT unit.

Okay that seems beyond my abilities, any idea what a reasonable price for having a shop rebuild it?

 

[JoshOnt]

" It does not stay up on land like it should nor in the water."

what does this mean? you trim the motor all the way up and it moves down on it's own? . if it sags down on its own, the seals holding the pressure are failing. look at your line connections from the trim motor to the fittings on the rams. there's fluid leaking someplace, or perhaps your out of fluid?

I went over everything connected to the trim unit I could find and thought it might be leaking from. Maybe I mistaked fluid for grease.

 

[Chris1956]

Some time ago, I had the Teflon seal replaced on one of my PTT cylinders. The rebuild kit with the teflon seal and a handful of orings was $30 and the installation was another $30 or so.

 

[JoshOnt]

Some time ago, I had the Teflon seal replaced on one of my PTT cylinders. The rebuild kit with the teflon seal and a handful of orings was $30 and the installation was another $30 or so.

Okay wow that is a lot cheaper than I was expecting, I was thinking it was going to cost me $300-500. Under $100 to fix it would be great.

 

[Chris1956]

Remember, probably only one cylinder is bad, but since they are hooked together, it is impossible to tell which one is bad. So either have them both rebuilt, or guess which one is bad. You might be able to isolate the bad one, by removing and plugging the hydraulic hoses on one cylinder at a time. When you find the cylinder that leaks down, that is the bad one.

BTW - where the hoses hook into the PTT pump/reservoir, is the check-valve body.

 

[Chris1956]

You will need to bleed the unit after each test. Originally the PTT unit used 5W-30 motor oil. Sometimes Dextron III ATF is substituted. Either is OK, but try not to mix them.

 

[roffey]

Could he be low on fluid. I would think if he's not low then there's no leak, if he is low then check for leaks?