Power Tilt/Trim drifts down after raising

[nebsivad]

I have a 1982 Johnson 140HP O/B V4 2stroke (p/n is J140TLCNB) mounted on an 18'(I think) 1977 Reinell tri-hull bow rider.
The problem that I have is after raising the motor to the fully up position via the hydraulic pump it will drift back down faster than I can even get the travelling stop flipped into place.
I have partially disassembled and reassembled the unit(screw-in valve assemblies only so far) using only an exploded parts diagram obtained from an online parts store trying to find an obvious problem but have not been able too yet. I really would like some "check-this-first" advice and if anyone happens to have a fluid schematic describing the way the system operates I would love to get my hands on that.
I have read some of the other postings about seals going bad but their symptoms are things like a slow drift or lockup. I was hoping my symptom, a fast drift, would be easy to find...
By the way, I have no fluid leaks externally.
This is the last step before re-commissioning it after quite a long rest.
Thanks ahead of time for any input.

 

[Joe Reeves]

Re: Power Tilt/Trim drifts down after raising

First, the obvious...... Check to see that the manual release valve is securely tightened.

If tightened as it should be, remove it to see that possibly the rubber tip seal of it might be faulty. Before removing it, look carefully into that access hole. If a lock ring exists, remove that first. If not removed, the manual valve "O"Ring will be destroyed upon removal and during installation of the valve.

If the above checks out okay, a fast letdown of the unit is usually due to one of the externally accessed check valves sticking open.

 

[nebsivad]

Re: Power Tilt/Trim drifts down after raising

Thanks. I will give that a shot and let you know.

 

[kenmyfam]

Re: Power Tilt/Trim drifts down after raising

As Joe,
Good Luck.