Help with Trim Up - Mercruiser - 1977 I/O

lornemilz

Cadet
Joined
Jul 20, 2012
Messages
26
I have been doing a restoration on this boat that I acquired a few weeks back.
1976 Searay V200
Mercruiser Motor and Outdrive
Ford 302 V8

Interior has been redone, transom replaced, motor was tuned up, etc. Before I took the boat apart I did a test on the lake and ran into some issues prompting the transom replacement. The tilt / trim was functional for a bit and then it wasnt. Upon re assembling this boat I am now faced with the tilt / trim issue all over again. I have been dealing with a local boat repair facility buying parts and asking questions and they have been extremely helpful. I have replaced the tilt / trim pump with a a newer 2 solenoid unit. My boat still has the original reverse lockout on it though its not wired up the lines still go through it.

I have replaced 1 cylinder arm due to a leak.

The new pump works great, the trim goes down quick and comes up quick.... at least at first. It appears that my "UP" lines are becoming pressurized and not relieving the pressure and locking the unit. I can trim all the way down and in the up trim it will travel about 3 inches and stop. The motor is still trying to go up but it cannot. If I crack the lines at the hydraulic arms the stern will continue to lift up while purging fluid. This is obviously not an ideal situation to have in the water so I am at a standstill with what to do. I have spent a good amount of time raising and cracking and lowering and cracking these lines only to have the same end result, the arms will not raise the unit more than once.

My hydraulic arms are the old skinny ones, the pump is newer 2 solenoid unit, fluid is straight 30w oil.

I know the cylinders themselves are ok because it will raise up and go down without issues it just wont keep doing it.

What can I do to resolve this issue.

All help is greatly appreciated.
 

flyrodman

Banned
Joined
Jul 6, 2012
Messages
19
Re: Help with Trim Up - Mercruiser - 1977 I/O

Sounds like your having a air problem as with any hydraulic cylinder will if there is a seal bad.Or air in the oil.Could be a newer 2 solenoid falty pump causing the air.Also,if the system isn't fully bleeded out of air will cause this.You either got a air,seal problem or that newer 2 solenoid unit isn't made for that vintage boat you have.Sometimes upgrading dosn't do what you want to do.
Or could be that the cylinders isn't right for the newer 2 solenoid unit.If your gonna upgrade the unit may as well upgrade the cylinders that goes with the unit.As modify,make them work.You either got a bad seal in one of the cylinder's or a bad seal in the pump unit causing the air.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,357
Re: Help with Trim Up - Mercruiser - 1977 I/O

My boat still has the original reverse lockout on it though its not wired up the lines still go through it.
I can trim all the way down and in the up trim it will travel about 3 inches and stop. The motor is still trying to go up but it cannot. If I crack the lines at the hydraulic arms the stern will continue to lift up while purging fluid. This is obviously not an ideal situation to have in the water so I am at a standstill with what to do.

Ayuh,... Welcome Aboard,... The problem is the reverse lock, is Locked....
 
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