Sail drive leaking gearbox oil ?

J

Jobs a good un

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Hi all
We have some gearbox oil leaking on top of the rubber around the sail drive .
Have checked oil levels and it looks like the have been over filled at last service .
Has anybody got any ideas as to why this is happening ?
Thanks for any reply
Regards
Mark
 
Jobs a good un said:
Hi all
We have some gearbox oil leaking on top of the rubber around the sail drive .
Have checked oil levels and it looks like the have been over filled at last service .
Has anybody got any ideas as to why this is happening ?
Thanks for any reply
Regards
Mark
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Incompetence on the part of your mechanic ?

You don't say what sail drive but there is not usually much free space above the oil in them. Id remove some oil so that the level is not above the full mark but check with your manual to see how the level should be measured. As a general rule ITYWF that screwed in dip sticks are not screwed in, just rested in place, to read the level while pushed in dip sticks are pushed in fully to read the level .... but check.

The worst case scenario is that a seal has been damaged as result of running an over filled box
 
Also check that the oil is clear yellow and not coffee / mocha colour due to emulsified seawater in the oil.

A full saildrive with a pool of oil lying on top of the diaphram was the first indication I had that my lower shaft seals had gone.

If the oil is at all brownish then a haul-out and seal change (two seals and two O-rings) is the only cure.

Richard
 
On the Volvo 130S sail drive unit there is a vertical slender tube, whose purpose is to allow the insertion of a tube to facilitate scavenging of its oil during maintainence. The tube is capped by a brass bung which has two "O" rings on its spigot. If either or both of the "O" rings becomes damaged, oil can leak past and run down the outside of the tube on to the diaphragm. The leak can be difficult to detect because the oil forms a very thin film around the tube's surface, but if it's surface is wet with oil that may well be indicative of the source of the leak.
Mike
 
At one time during its production life the Yanmar SD50 fitted a modified oil dipstick with a longer shaft. It was to reduce the oil level in the saildrive. With too much oil, it spat an excess through the engine input shaft seal due to overpressure. Conceivably, this could leak from the engine bell housing joint onto the gaiter seal below.

I thought that I had this issue with mine. In the event my issue was something quite different.

If oil has been blown through the engine shaft lip seal, there's a fair chance that no harm has been done. It's fairly straightforward to check pressure integrity. I made the set-up shown in the picture using a couple of fittings, a car foot pump, a gauge and a non return valve. My saildrive held 3 psi for 10 minutes without any loss.

DSC_0003%20small_zpsegzlyz6l.jpg
 
Halo said:
Is the o ring seal around the filler cap in good order.
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RichardS said:
I'm not sure what suggestions you are looking for Mark. If the saildrive was overfilled and the engine then run up to temperature it would be expected for oil to force it's way past the filler cap and run down the outside onto to diaphram.

Richard
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Filler cap ???

What drive is this then ??
 
Hi all
Many thanks for advice , have now removed over a cm into the bottom of bowl , waiting till storm blows over before testing .
Regards all

Mark
 
RichardS said:
The OP confirmed that the filler cap O-ring was in good condition so I assumed that his saildrive did have one. Certainly my Yanmar SD20s have yellow filler cap / dipstick holes.

Richard
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Richard, the Volvo 130S sail drive's filler does not act as a vent. It is a solid plastic threaded plug which tightens down onto an "O" ring. I'm not sure if the saikdrive is in fact vented. Whenever I unscrew the filler plug to check the oil level there is a slight whoosh as the captive pressure in the gear case equalises with atmospheric pressure. Whether the trapped pressure was higher or lower than ambient I've never been able to accurately determine.
Mike
 
mikegunn said:
Richard, the Volvo 130S sail drive's filler does not act as a vent. It is a solid plastic threaded plug which tightens down onto an "O" ring. I'm not sure if the saikdrive is in fact vented. Whenever I unscrew the filler plug to check the oil level there is a slight whoosh as the captive pressure in the gear case equalises with atmospheric pressure. Whether the trapped pressure was higher or lower than ambient I've never been able to accurately determine.
Mike
Click to expand...

It's not a vent on the SD20s either ....... but if you fill the saildrive to the top with oil and then heat it up by running it I can guarantee that oil is going to come out somewhere. If you're lucky the weak link will be the filler cap.

Richard
 
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