Power TiltTrim Problem

"I have a Merc #1 setup (H

"I have a Merc #1 setup (High-Low pressure Prestolite unit)and the drive is very slow going up (works great in down position). I replaced both trim cylinders due to faulty seals and a worn shock piston, flushed, bled and filled w oil but it still has the same problem. How can I narrow this down to the pump or motor?

Thanks"

"GFJ:

It sounds like the up

"GFJ:

It sounds like the up valve is not 100%. Does the pump sit over a clear reservoir tank? If it does, remove the reservoir and check the valve screens for dirt.

You can get the service manual for that year merc. from eBay. There are a series of tests to determine if the valve body of the pump needs work.

Mine works at the same speed for 20 years old, it's just noisy in the up mode. When it quits I'll replace the motor with valve body.
Guy"

Guy:

There is a black reser

Guy:

There is a black reservoir (w. bleed screw and fill screw). It is the older type setup and I've been told that the up side is high pressure and the down side is low. The boat is an early '70s model. Have you had experience with this setup?

Thanks

"Go Fast Junkie.
I have one o

"Go Fast Junkie.
I have one of mine doing the same thing.
The hydraulic cylinders are fine and I recond the pump last winter.
I am pulling mine out of the water soon for the winter and are going to have a close look at the hydraulic hoses, I have seen the inside of these small hydraulic lines collapse before and give problems with restricting oil flow.
Cheers
Peter C"

"Peter:

I think you are on

"Peter:

I think you are on to something with the hoses! A restriction in one of the lines does seem to me would cause the problem we are having. Have you disconnected the rams from the aft end of the drive and observed the rams? One of mine is not operating the way it should. I also noticed that fluid was leaking from that ram where the hydraulic lines attach. It required tightening the lines more so than usual which I thought was odd at the time but never looked closely at the lines themselves. A collapsed line would build up pressure at that point and the down side has the highest pressure of the 2 circuits. I'm going to have another closer look at everything. I'll keep you posted on anything I find. Thanks for your feedback, I appreciate it!

Regards, Jack"

"Jack
Yes, I have disconnecte

"Jack
Yes, I have disconnected the rams and one ram is much slower than the other but as my boat lives in the water for over half the year I havent realy investigated the problem yet.
I just know from past experiance in Hydraulics that I have seen these small ID Hydraulic lines colapse before and restrict flow.
As I have already done the pump and rams I am just inclined to think I have a hose problem.
Scene it is starting to get cold here now my boat will be coming out of the water in the next few weeks and I can investigate the problem then.
Cheers
Peter C"