Tilt/trim won't hold

gfbiii51

Petty Officer 2nd Class
Joined
May 28, 2011
Messages
140
I have a 1982 3 cyl. 70 hp Mercury.

I bought it on one boat and had it moved to another. I did not notice a problem before the move.

Now it will not stay in a full tilt position nor will it hold a trim under way.

I do not see a hydraulic fluid leak.

I have the operator's manual for the motor. It says to check the oil at the full up position.

The first time I did that, I noticed the vent screw was open. I opened the oil fill screw but couldn't see the oil level. The unit is on the transom and I couldn't see in the opening to check the level.

I convinced myself the vent screw should be closed and did that. I ran the motor full up to full down several times to bleed it . It still didn't hold position. So I ran it full up and checked the fluid level. Oil burped out, maybe a spoonfull. I cycled it a few more times. Still didn't hold. I checked the oil again (with the motor up) and a similar amount of oil burped out.

I have the SELOC manual for this motor and it is not really helpful. I've tried to find the appropriate Mercury manual on-line from the references provided here and couldn't find one for this motor.

One more thing which may or may not be related. I have to hit the tilt/trim switches several times to activate the pump. The solenoid clicks but nothing happens.

I've tried to search this forum for this issue with no success.

I'm just getting more confused.

Specific questions:

Vent screw open or closed for operation?

Check oil with engine up?

Any suggestions for fixing the problem?

Thanks
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Tilt/trim won't hold

lift engine all the way up and top off oil until it dribbles out of the filler hole. cycle two times and check again. if it bleeds down when full then your check valves are going bad. the pressure settings are determined by springs and based upon horsepower brackets - 30-60 and 60-120. putting same engine on different boat does not change the bracket.
 

gfbiii51

Petty Officer 2nd Class
Joined
May 28, 2011
Messages
140
Re: Tilt/trim won't hold

Thanks RRitt. I finally got some oil and tried this today. Oil ran out of the filler hole when the screw was removed so I must have valve problems. Thanks for the tip.
 
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