Mercruiser 4.3 oil in bilge area

[Richardc]

A big hello from the UK. Hope you can help? I've recently bought a c.1990 Maxum with 4.3 merc inboard. Today I noticed a big drop in oil pressure and lifting the cowling revealed at least a litre and probably two of engine oil in the bilge area. I got a tow back to shore and cleaned the engine up - no visible signs of failure, and nothing stupid missing (sump plug, oil filter etc). Refilling the engine with oil, it now has normal pressure and no leaks. The boat has been out of use for a year, so I wonder if I may have blown an oil seal somewhere? Or have a blocked breather? But why would it not be leaking now? It is possible that water could have entered via the exhaust and washed the oil out? If so, where would it have come from? Appreciate any thoughts. Rich.

 

[tommays]

Re: Mercruiser 4.3 oil in bilge area

about the only think you can do is put the engine box on the dock and have someone drive the boat while you keep a carefull eye on it <br /><br />bring some extra oil and dont go to far from the dock <br /><br />i think the leak will show up and than you can find a cure <br /><br />tommays

 

[trog100]

Re: Mercruiser 4.3 oil in bilge area

a missing 2 litres of oil would take the level down to at or below the oil pump pick up level.. thats your big drop in pressure exlained..<br /><br />quite how the oil left the engine and ended up in the bilges isnt so easily explained thow..<br /><br />it might be a slow leak that u havnt noticed.. if it did leak it should still be leaking..<br /><br />u noticing the sudden drop dosnt mean the oil suddenly all poppped out all at once.. the sudden drop of pressure happens when the oil level reaches the critical pick up level which is about 3 or 4 pints low.. above that it would not make a difference to oil pressure at all.. so i think u have a slow leak.. and its still leaking..<br /><br />trog100

 

[achris]

Re: Mercruiser 4.3 oil in bilge area

Rich,<br /><br />Check the sump very carefully. They are the standard automotive pan (pressed steel) and they DO rust. The hole will actually be covered by the paint. The reason I know is I did one on a friends boat about 6 months ago and I did mine about 5 weeks ago. The area to look the closest at is around the sump plug, that's the lowest point and where the water drips stay the longest. <br /><br />The bottom of the pan is quite small and you could have been running on as low as 1 litre of oil. <br /><br />Chris............

 

[Richardc]

Re: Mercruiser 4.3 oil in bilge area

Thanks for all your replies - I cleaned it all up and tested in the water today - the culprit is a rockercover gasket on the starboard side. Whether it failed of its own accord or that there is some other issue with the oil system (i.e. blocked breather) I'm not sure. Anyway, at least it's not engine-out territory! Thanks, Rich.

 

[trog100]

Re: Mercruiser 4.3 oil in bilge area

and check your oil level more often.. he he..<br /><br />u are probably more lucky than u realize.. reach that critical none pick up level under full power and its goodbye engine.. honest..<br /><br />trog100

 

[MH9371B]

Re: Mercruiser 4.3 oil in bilge area

How hard is that rocker cover gasket to change? I noticed a small leak near mine as well.

 

[Bondo]

Re: Mercruiser 4.3 oil in bilge area

That Depends,...............<br /><br />Getting the cover Off,+ Back On, is sometimes Near Impossible, without atleast loosening the Exhaust Manifolds........<br /><br />Some center-riser manifolds,+ some valvecovers are better or worse........<br />

and check your oil level more often..

I think Once a Day,..... Or Every Time You Touch the Key....................<br />Ya Know,............ The Sniff Test,+ Oil Check.............<br />Should be on every boater's Check List..................