Volvo dph drive trim 'sinking'

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julians

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Got an issue with my vp dph drive.

if you trim up the drive up, it will lift as it should but then will sink back down over a period of about 10 seconds seemingly from the thrust of the prop. If you trim with the engine off or not in gear the drive lifts and stays in position.

The power trim reservoir is full of fluid, I'm guessing that a seal has gone is the hydraulic system somewhere, but has anyone else had this and know exactly what the cause is likely to be?

It was working fine yesterday, with no sign of any issues.
 
Exactly where is problematic unless you can see fluid spoiling the sea surface. Could be reservoir pump or ram. Hopefully it's reservoir pump as they are cheaper and easier to replace. Try swapping them around if you are twin engined and see where the problem re-manifests. I have DPD/E drives and the pins in the transom shield if yours are anything like mine are just nasty, real nasty, to get out without an engine liftout. Pray it's the reservoir pump assembly or a failed hose
 
BTW. if it is your rams, before you go and buy new, speak to me first if you want a brand new pair reconditioned. I damaged a pair by cross threading the hoses, bought another pair due to timescale issues and sent these ones in to a hydraulics firm to have a proper threaded insert fitted rather than the soft ali ones tapped into the rams from oem. They are now spare, never used.
 
Only got a single engine so can't swap parts over.

I've got no oil leaking either externally or internally. From googling it looks like the valves in the pump assembly eventually fail causing these symptoms. And it looks like you can't buy the valve separately they have to be bought as part of the entire pump assembly which is just over 1000 euros - nice.
 
Have a look around. I think Keypart may stock them, for mine an aftermarket pump assembly is half the price of a pair rams. About 250 quid
 
Hmmm, so whilst I was at Anchor I ran the drive through the full range of trim 3 or 4 times, and now on the run back to the marina it's all working fine again.

Not sure how long it will be working fine for, but I'll take that rather than spending a grand on a new pump unit.

I understand that the valve can get blocked by debris in the fluid, so maybe by running it to its full extent I shifted the blockage.

Is it worth draining the fluid fully and replacing with fresh to ensure its all clean?
 
I guess that is a rhetorical question but it certainly cant harm. I did mine by empting the reservoir and refilling. Then from full in went to full up. Drained again and refilled, then went full down, drained and refilled a couple times. I bought 5 litres of hydraulic fluid and was left with half after doing this for both reservoirs. No chance in hell was I going to fiddle with the ram hose connectors again. Too much pain that way.
 
julians said:
Is it worth draining the fluid fully and replacing with fresh to ensure its all clean?
Click to expand...
I think it is .
I had a pump go faulty with the leg going down and ended up with a new pump. Had I changed the fluid it may have prevented the problem developing.
Perhaps not annual event but certainly every few years .
 
BruceK said:
I guess that is a rhetorical question but it certainly cant harm. I did mine by empting the reservoir and refilling. Then from full in went to full up. Drained again and refilled, then went full down, drained and refilled a couple times. I bought 5 litres of hydraulic fluid and was left with half after doing this for both reservoirs. No chance in hell was I going to fiddle with the ram hose connectors again. Too much pain that way.
Click to expand...

Was there much debris in the old stuff that came out?

And how did you drain it, just suck it out of the reservoir with an oil pump?
 
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I dont know if any debris came out. I can say the oil was very slightly emulsified. However considering the ram is in sea water it's not hard to envision some water ingress over time when deploying them and more so if any larval barnacles etc made it past the seals. It's a bit of a harsh environment and having become acquainted with these rams can say there is nothing particularly special about them that would ever really prevent this.
 
BruceK said:
BTW. if it is your rams, before you go and buy new, speak to me first if you want a brand new pair reconditioned. I damaged a pair by cross threading the hoses, bought another pair due to timescale issues and sent these ones in to a hydraulics firm to have a proper threaded insert fitted rather than the soft ali ones tapped into the rams from oem. They are now spare, never used.
Click to expand...

you can replace the seals on the DPE rams
depends how much DIY you want to do
 
simonfraser said:
you can replace the seals on the DPE rams
depends how much DIY you want to do
Click to expand...

Certainly better than taking ram pins out that's for sure and avoiding tearing a seal is also a hazard to be overcome. However even the ram bodies eventually need replacing in time. On mine the time had come
 
Just drained the old fluid out, I couldn't see any significant particles, but it was a horrible dirty brown colour,definitely not clear, I took some photos of it, if anyone wants to see them let me know and I'll put them up.

I also had a look in the manual to see if it specifies a change frequency for the trim fluid, but surprisingly it does not, so I wonder whether this fluid has never been changed and is therefore 14 years old.
 
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