Volvo DP Leg won't staytrimmed

Thepipdoc

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Just had both of the VP DP90 legs serviced and everything was fine when the legs were removed, they both had the obvious bits replaced i.e. all gaitors, bellows, anodes, oil etc.
All appeard to be OK when I took the boat out until I went on the plane - the port leg would not stay in the "out" position. It would stay where I positioned it for a minute or so and then it would eventually start to move back to the fully down position.
I spoke to the people that serviced the legs and they decided to swap the port and starboard trim pumps over to try to find if the problem was in the port pump. The problem has stayed on the port side so it can be assumed that the problem is not with the pump, but almost certainly the ram seal/s.
My question is - should the rams be tested as part of the service?
 

jparham

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Hi PipDoc,
Not sure how you would know the seal is about to give even if you did test it.
I agree it is strange how a perfectly good pair of rams when the boat is serviced and showing no signs of leak and lifting properly when boat is removed from water, suddenly starts to mis-behave when it goes back in.......
Something to do with crud in the bottom of the cylinder and this being the only time you tend to have the legs full up could cause leaks around the scraper ring perhaps.
I will certainly be testing mine, but the only test I can think of is put the drive up as far as possible and hang a weight on the prop end.....
Luckily the difference between trimmed in (-4) and optimum trim (-2) on my F33 doesn't make a whole lot of difference.
 

whisper

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Just had both of the VP DP90 legs serviced and everything was fine when the legs were removed, they both had the obvious bits replaced i.e. all gaitors, bellows, anodes, oil etc.
All appeard to be OK when I took the boat out until I went on the plane - the port leg would not stay in the "out" position. It would stay where I positioned it for a minute or so and then it would eventually start to move back to the fully down position.
I spoke to the people that serviced the legs and they decided to swap the port and starboard trim pumps over to try to find if the problem was in the port pump. The problem has stayed on the port side so it can be assumed that the problem is not with the pump, but almost certainly the ram seal/s.
My question is - should the rams be tested as part of the service?[/QUOTE

Don't think they'd normally be tested unless a problem had been hinted at.
Hope you don't have what we did last year - scored rams. Apparently a common problem on 10yr old VP legs. Ended up having ram "shafts" welded and re-polished in a Black Country "sweatshop", which seems to have cleared the problem. Otherwise, it may involve the complete removal of cylinders from the leg - horrid job and possibly very expensive.
Good Luck.
 

Thepipdoc

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Thanks All.
I spoke to the people that serviced the legs and apparently the rams aren't included in the service! Pretty much what I thought.
They said they will however do me a "special price" on the lift because I'd only just had the legs serviced by them.
 

volvopaul

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Hi sorry but the engineer cannot be blamed for your ram seals, as they have been tested by swapping the pumps over so its not the valves in the pump ( im surprised though) as it usually is if there are no visible leaks on the ends of the rams.

I ALWAYS ask about trim issues on older boats when servicing drives as thats the time to fit new rams when the drives are off, another tip is to fit 2 new rams not just one as the other one will fail next and as there plumbed together, one good ram my not keep the drive trimmed out to where you want it, so bite the bullit and fit 2.

There not cheap, also if the inner pins are seized in the shield or installation does not allow access to the bottom of the shields its engine out to do it.
 
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