View Full Version : Trim pump

07-08-2013, 07:01 PM
I am kinda stumped. My drive will stay trimmed all the way up but at anything less than all out the drive will slowly drop.

07-08-2013, 08:22 PM

Section 5 of the Merc manual on the oildyne pumps. May come in handy. Nothing real specific as to your problem.

I doubt an electrical issue, so focus on the mechanical. Unfortunately, the test procedures require a special set of gauges for most testing.

FWIW..If I was to guess, pressure relief valve or seals in the pump.


07-15-2013, 05:16 AM
Thanks bob. I think a new pump might be the way to go !!

07-15-2013, 10:30 AM
Here is one....


07-15-2013, 10:33 AM
and one by me....


07-15-2013, 11:43 AM
Sounds like you have a small spec of junk at the valve, before you spend $$ a simple try is to borrow a pair of trim lines. Disconnect yours and install the other set, put the ends into a cut off clean jug. Put enough oil in the jug to insure they don't suck air, fill the resivour then cycle the pump up and down a few times. Many times running the pump a max free flow will pass the junk out of the valve, also it is very easy to remove the valve body to clean. 90% of the time I have found tiny bits of Teflon tape being the cause.


07-15-2013, 07:19 PM
Good idea Phil i will try that first. If not. Thanks Bob !!