Light grey smoke at idle. Mercruiser 6.2 efi Any ideas?

[robm3]

Hi all,
My boat engine has a little smoke at idle, it's light grey (not steam) and not too bad. If its been sitting for a few weeks it's a little heavy for 20 seconds.
My dipstick shows it slightly overfilled, could this be the problem?

Or something's else?

Motor has only 260 hours...

[mickrick]

White smoke is water, blue smoke is oil, black smoke is fuel. Maybe it´s over fuelling a bit on idle?
If it´s overfilled with oil, drain some off. Overfilling with oil is not good.

Is it diesel or petrol? Does it do it when it´s warm? A bit of smoke from cold is normal, even more so if it´s not been run for a while.

Edited by mickrick on Tuesday 27th August 07:57

[robm3]

mickrick said:

White smoke is water, blue smoke is oil, black smoke is fuel. Maybe it´s over fuelling a bit on idle?
If it´s overfilled with oil, drain some off. Overfilling with oil is not good.

Is it diesel or petrol? Does it do it when it´s warm? A bit of smoke from cold is normal, even more so if it´s not been run for a while.

Edited by mickrick on Tuesday 27th August 07:57

hmm if its white smoke could water be seeping in through a head gasket or something?

It's a petrol, does it when cold and warm (more so when warm).

[PugwasHDJ80]

Bet its not grey- bet its blue.

Probably oil draining through the valve stems very slowly- at rest more oil drains through into the cylinders, which is why you see a puff at startup

[mickrick]

A quick sniff, and you´d know straight away if it´s oil. But how do you explain a smell in words?
How overfull with oil was it? That could be your problem.

Edited by mickrick on Saturday 31st August 08:07

[MOTORVATOR]

How is it set up Rob? Straight through exhaust or on a y pipe through the leg?

High oil level could indicate something being added Water / Fuel. Check the oil for milky / smelly. When was the last time you chopped the water seperator over, dirty fuel can cause it. Are the headers staying cool, lack of raw water pressure at tickover could be the problem, turning to steam on exit. Assuming it is closed cooling then a head gasket will show up in the water tank. The crankcase breathers will build grey smoke if the bores are not holding oil and that is reinjected as airflow but should clear when burnt unless you have a huge problem. Take a breather off and see what you are getting.

[robm3]

Thanks for the info guys, checking through the prior receipts (i've had the boat for three years but it's 9 years old), I cant see the Risers and Manifolds being changed at all. This is a five year max job when used in salt water, ive also got some rust around the joins on them so I strongly suspect they are leaking and causing the smoke. Could be a costly engine stripdown if I dont replace them I suspect.

So going to swap them out, refresh the gaskets, throw in new spark plugs and drain some oil.

I'll throw some pictures up too, should get started in a few days once I get the right parts ordered.

Although just seen the price of parts:

http://www.ebay.com.au/itm/151109792360