very odd tilt/ trim behaviour

115 Mariner 2 stroke 4 cyl outboard...# OD211932 ( 93 ' I think )

PROBLEM :
Tilt trim moves motor either UP or DOWN BUT NOT BOTH WAYS....

WHAT I HAVE DONE:

Relays have been checked and are OK
Replaced the brushes on the motor recently
Replaced manual release valve/screw
Brand new battery

MY STORY :

I've been forced to use the Manual Release valve to tilt the motor UP so I can get it out of the water...I've done this a half dozen times due to issues w/ the tilt trim...my mechanic said to replace the manual release valve and top up the fluid for starters...I've done both.

Here's the odd part...when I adjust the valve one way (counterclockwise) the motor will go UP but not DOWN....if I rotate the valve the other way ( clockwise) about a full turn, the motor will then go DOWN but not UP.

Is there some magical spot where that valve need to be set ??

My reasoning is the motor and electrical are ok ( motor will travel both up and down ) and that I've buggered up the hydraulics somehow by using the manual release valve....

Or is this indicitave of another issue ?

cheers

Greg

Re: very odd tilt/ trim behaviour

show me a pic of your trim system. I think you have same system as used on mercury force - in which case I've fixed this same problem a bunch of times and it has been in pump/manifold every time.

Re: very odd tilt/ trim behaviour

The release screw must be screwed all the way in to operate, at that point and the trim won't go down but will stay up and the trim motor runs in the down position there must be a shuttle valve it the pump stuck or the system is just a little low of fluid.

Re: very odd tilt/ trim behaviour

Your motor had two possible trim systems.
I am working on assumption that yo have single ram instead of three ram system. Did you keep your old manual release (or inspect it before throwing away)? Was the tip broken off? If so, where is the tip now?

Re: very odd tilt/ trim behaviour

RRitt said:

Your motor had two possible trim systems.
I am working on assumption that yo have single ram instead of three ram system. Did you keep your old manual release (or inspect it before throwing away)? Was the tip broken off? If so, where is the tip now?

Click to expand...

It is a single ram system.

The old release valve is still in one piece ( no broken tip )...the three black O-rings look a little worn and the slot in chewed up from turning it out.

cheers

Greg

Re: very odd tilt/ trim behaviour

Laddies said:

The release screw must be screwed all the way in to operate

Click to expand...

ok good...thought so.

cheers
Greg

Re: very odd tilt/ trim behaviour

* new development *

Just went to check the boat...raised the motor using the tilt/trim about 15 degrees from full down....now there is a hydraulic leak coming from the pump side...first time I've seen any fluid leaked out...fair bit on the ground, covers about a square foot.

cheers

Parksy

Re: very odd tilt/ trim behaviour

as far as I know there are only two obvious and simple causes ....

broken tip from release valve plugging up the manifold (surprisingly common)
not enough fluid in system (too obvious to be overlooked)

You are absolutely sure that the tip of release valve did not break off inside manifold? If so, then screw it. Just rebuild the whole thing from top to bottom.

My attitude towards trim system is that if it isn't something simple and obvious then it isn't worth trying to figure out exactly which part broke. It almost always takes me less time to do a complete rebuild than to track down and fix one single part.