Marksskagit

Have volvo duo-prop S drive and it's starting to creep up after its been set for cruise modeHaven't noticed any fluid missing from the reservoir, so i'm thinking the pressure relief valves are worn. Has anyone rebuilt these, and can offer any advise etc. Any help is most appreciated. Thanks

Can you explain the problem a bit more? I couldn't quite work out what you are saying is happening?

aliboy said:

Can you explain the problem a bit more? I couldn't quite work out what you are saying is happening?

Click to expand...

Sorry, my brain and my typing fingers are not on the same wave length, its the leg trim thats creeping, usually run it at -4 on the guage, but after a few minutes it creeps up to -3 then -2 then -1 etc.
I guess I should have said leg trim in the title, which would have saved alot of embrassment
Hope this helps you.
Thanks,
Mark

Is it the actual trim or just the sensor? The sensors on the DPS are rubbish and give lots of problems. For the trim to creep 'up' whilst running forward would be less likely as the force of the props is trying to make it go more negative. To 'creep up' I suspect that the trim pump would have to operate and you would probably hear this happening. First suspect is the sensor, but you could check by setting the trim, running the boat until the trim 'creeps up' and then use some type of before and after measurement of the real position of the leg to see if it really moving as indicated by the sensor/gauge.

Hello... I have the same problem on one of my DP A drives. I have replaced both sensors due to other reasons and this did not fix the problem of creep on one drive. It is visually creeping up, both undeway or stationary at dock, very very slowly either running or with engines off. You would never be able to hear the pumps over the noise of the diesels, and it happens when all power is off, so I can say it is not the pumps going on. Out on the hard when in winter storage it is a measureable couple of inches of creep up. I too would be interested in suggestions as this is something that is a constant over 5 years. I thought maybe air, so I tried full up & down a few times to work any air out. Also changed out the fluid in both drives and cleaned out the reservoirs and added fresh transmission fluid per the manual, not hydraulic oil, just incase there was contamination..... so what do I try next??

Almost has to be air. The fluid isn't compressible and it won't lift the leg against gravity without added power. How did you bleed the system when you changed the fluid, and are you using any fluid?

Didn't bleed the system, but changed fluid in both drives with Transmission oil. Just took off the reservoir, cleaned it out, put it back, then filled it up. Thought exercising the drives automatically dispelled any trapped air. There are no leaks evident so I too think trapped air, but only on one drive? Is there a bleed process? Not keen on messing with the actual cylinders, which I suspect your are going to suggest as the bleed point.