VP DuoProp drive losing oil - help?

jmvan

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Sep 24, 2007
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11
Hi Everyone
I have a Volvo Penta DP-SM drive coupled to a VP 57GSI PEFS motor with about 500 hours logged. For about two years now the boat has been back and forth to the shop with the same problem. The drive is losing oil, ie. the oil level is down, but on three of the four occasions it was inspected, there was no water in the oil. (By down, I mean no longer showing on the dipstick.)

The boat is in a slip so checking the oil level on a weekly basis is not possible. Typically it goes into the shop, they pressure test and vacuum test, pronounce everything OK and the leak reappears in three months.

How do I know its leaking? The first sign is oil on the water on startup. Usually not so bad, but recently a problem. Also, when raising or lowering the drive, without having run the engine, I can see oil on the water. Once the engine is warmed up it goes away completely.

The engine does not burn oil, nor are the trim cylinders leaking.

The oil leaks are quite small so it is only a few drops each time. Over time it obviously builds up to the point where the level is low.

The boat was hauled out last Monday for the latest leak. When the oil level was inspected at the shop there was a significant pressure release as the dipstick plug was removed, ie. the drive holds pressure but no oil on the dipstick. This is consistent with their pressure and vacuum testing. I believe it is a small leak at low pressure that is sealed as soon as any pressure is applied.

Has anyone any experience of this sort of problem, or can give any clues as to what to look for?

Despite all this I am on good terms with the shop. They are a VP repair shop and are competent. Needless to say I want to get it fixed.

Any experiences with this type of problem?

Thanks
 

Don S

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62,321
Re: VP DuoProp drive losing oil - help?

Has the outdrive been pulled and the bellows checked for oil?
 

jmvan

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Sep 24, 2007
Messages
11
Re: VP DuoProp drive losing oil - help?

Thanks for the response. Not yet for this haulout. On previous occasions this was never mentioned as a problem. I will be visiting the boat on Thursday and will ask. There are no leaks of water or oil inside the boat.
 

Don S

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Re: VP DuoProp drive losing oil - help?

The most common leak on those drives is the input shaft seal. It leaks into the bellows. I assume you are not taking it to a certified Volvo Penta dealer, correct?
 

jmvan

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Sep 24, 2007
Messages
11
Re: VP DuoProp drive losing oil - help?

No, they are a certified VP dealer. The input shaft seal was replaced in early 2008 by a non-VP shop. I wasn't happy with what they did so I switched to the VP shop. Could an input shaft seal be causing the symptoms I have described?
 

Don S

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Joined
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Messages
62,321
Re: VP DuoProp drive losing oil - help?

Could an input shaft seal be causing the symptoms I have described?

Sure it could cause it. When they do the pressure tests, the engine is not running, so the input shaft is not turning. Did they actually drain the gear lube out of the drive before doing a pressure test? If not, no wonder it didn't leak down.
 

jmvan

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Joined
Sep 24, 2007
Messages
11
Re: VP DuoProp drive losing oil - help?

Thanks for your input. I am not sure if they drained the drive. I presume so, but will ask on Thursday.
 

jmvan

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Joined
Sep 24, 2007
Messages
11
Re: VP DuoProp drive losing oil - help?

I spoke to the shop on the phone. They do test with the oil drained, and there is no oil in the bellows. They report that the drive holds vacuum and pressure. This is a repeat of the previous four instances. Yes the drive holds pressure, but it still leaks just sitting there. There is some grooving on the propshaft. They are suggesting that the oil is getting past the first seal when not under pressure then leaking past the second (which faces the other way). Does this sound as though they might be right?
 
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