Cobra Out Drive Falls over time

[aswetich]

1995 OMC Cobra Outdrive on 5.0 engine. Last year when trimmed all the way up it would slowly fall after a few days. Just took the boat out of storage and now it falls after about 8 hours. No leaks and fluid is topped off. The boat only has 300 hours. Where should I look for the problem 1st ?

 

[icyveins]

Re: Cobra Out Drive Falls over time

Valve seats, the fluid is getting back through the valve back into the reservoir.

 

[aswetich]

Re: Cobra Out Drive Falls over time

I have the service manual but don'y know where the valve seats are. Can you provide some detail on where they are and what's involved in replacing them ? I can then use the manuals for the detail. Thanks

 

[icyveins]

Re: Cobra Out Drive Falls over time

Probly have to start with looking at the trim pump parts diagram, you probably have one "spool" with sets of O-rings on that spool. More than likely what is happening is the spool is coming back to center but allowing fluid to pass by the O-ring back into the reservoir. I would need a serial number to get the correct illustrations

 

[aswetich]

Re: Cobra Out Drive Falls over time

Is there a easy way to determine if its a cylinder leaking down or the valve body in the pump ? It's falling all the way down in about 2 hours so is it most likely in the valve body ? Should I just buy the pump rebuild kit ? Model: 502APHU Prod#: 3868156 SN:T0792142

 

[icyveins]

Re: Cobra Out Drive Falls over time

if you don't have a visible leak on the outside of the cylinders or lines running to the pump, the leak is internal. trim pump seal kit is what your going to need. part number #3854397 51.00$ if you are unsure about doing the repair yourself maybe purchase the kit and have a hydraulic shop locally do the re-seal for you.

 

[aswetich]

Re: Cobra Out Drive Falls over time

I got the pump kit and also kits for both cylinders. After rebuilding the pump and cylinders per the manual its still doing the same thing.
When its trimmed up it falls about 1/4 of the way in about 1 hr and 3/4 over night. When trimming up it goes at the normal speed an sounds fine. When trimming down it's very slow and sounds different.