Lower unit trims down by itself,What's wrong?

[onlyfinol]

Okay, this is 1992 OMC 3.0L Cobra. When the boat is not in use, out of water, the lower unit droops, however, it does not happen right away, it takes a full day to do so. The trim works fine since bring up and down the lower unit as it should. Now, if the lower unit is all the way up, and it is push down manually by applying weight to it, the lower units start to drop as well. All this happen while is out of water and not running.
What is wrong?
Please, help me with this situation.
Thanks

 

[Haut Medoc]

Re: Lower unit trims down by itself,What's wrong?

I'm not an OMC guy but......
You have a leak somewhere in the system.....​

 

[thrasher]

Re: Lower unit trims down by itself,What's wrong?

by system, he means the hydralic trim system. There is an internal leak that allows the weight of the outdrive to force oil out of the trim cylinder back into the reservoir, allowing the drive to sink down. If the leak was external, you would see oil on the floor or in the boat. As you don't mention this I assume it's an internal leak probably inside the trim motor unit. I guess this is not too much of a suprise in a boat that is 10 years old. You need to either dismantle the trim motor and overhaul it or change the unit for a new one. I would recomend reoplacing the unit as the motor bri=ushes and bearings are probably tired so if you fix the hydralics, something else will fail a little bit later..

Gary

 

[Rob454]

Re: Lower unit trims down by itself,What's wrong?

You have a leak somewhere.
Rob

 

[onlyfinol]

Re: Lower unit trims down by itself,What's wrong?

Gary,
You mean the whole unit system? Such as pump, hydralic arm, etc..

 

[Don S]

Re: Lower unit trims down by itself,What's wrong?

Gary,
You mean the whole unit system? Such as pump, hydralic arm, etc..

Somewhere in that system is a problem. No it is not a one answer will cure it type problem. You will need a gauge manifold and a manual to test it properly.

 

[onlyfinol]

Re: Lower unit trims down by itself,What's wrong?

Okay, I will see what I can do.
Thank you all!!

 

[thrasher]

Re: Lower unit trims down by itself,What's wrong?

I'm not sure what a gauge manifold will tell you on the hydralic system, but I was suggesting you change the pump unit. The plungers inside the hydralic rams could be leaking, but it is far more likely to be a problem at the pump unit. Don's advice is always good, so if you can check it as he suggests it would be the right thing to do, failing that I would start looking at the pump unit for the cause of your problem.

Gary

 

[Don S]

Re: Lower unit trims down by itself,What's wrong?

The gauge manifold is a special tool, it has a couple of gauges and high pressure shutoff valves. With it and the manual you can determine if the rams or pump are bad, or spend a large amount of money replacing parts till you find the problem.

 

[Rob454]

Re: Lower unit trims down by itself,What's wrong?

Youre better off geting the tool and finding out whats wrong rather than replacing parts and guessing whats wrong. that could get really really expensive really really quick. Youmay even want to take it to a shop let them tell you whats wrong and let them fix it. if they misdiagnose it thats their problem. I wouldnt pay. until they fix it right
Rob