Acrid grey & black smoke from exhaust...

[GM182]

...likely to be oil mixing with fuel?
What can cause this?

Background: I've just got my 107,000 mile Alfa GTV V6 back from having the alternator replaced and drove home in heavy traffic yesterday with no problems.

This morning my wife was going to nip to the shops while I was out and said there was lots of smoke so she turned back after 1 mile.

I've just been for a couple of miles this evening to get it up to temperature and the smoke is definitley there.

Oil level is fine and I felt the engine might be one of the few things not to go wrong with this bd car.

[davepoth]

Couple of things can cause this. Best case is overfilled with oil for some reason - check the dipstick. Next check the crankcase breather. After that it gets expensive.

[GM182]

Hmn. Oil level exactly midway between min& max.

crankcase breather - forgive my ignorance but is that to allow some air in then?

Expensive would basically mean scrapping it as i can't keep throwing good money after bad...

[Baryonyx]

I was going to say, if you were driving a diesel then this is to be expected.

[Slidingpillar]

If an old car did this my first thought would be the choke mechanism getting stuck.

Wires off the temperature sensor so thinking the engine is cold and enriching accordingly?

[GM182]

Baryonyx said:

I was going to say, if you were driving a diesel then this is to be expected.

Ha! If only it was just that!

[GM182]

Slidingpillar said:

If an old car did this my first thought would be the choke mechanism getting stuck.

Wires off the temperature sensor so thinking the engine is cold and enriching accordingly?

I was thinking of maybe just taking it for a bit of a thrash and see if it clears?

[HustleRussell]

If it's black smoke then it could get expensive. Valve stem oil seals or even piston rings. If it's either of those things the engine will probably run fine for many more thousands of miles albeit with greater fuel consumption...

Edited by HustleRussell on Sunday 3rd February 19:51

[GM182]

HustleRussell said:

If it's black smoke then it could get expensive. Valve stem oil deals or even piston rings. If it's either of those things the engine will probably run fine for many more thousands of miles albeit with greater fuel consumption...

The problem is I have just put in a new clutch and alternator because it had good service history and I thought it would be possible to sell on for what I paid or a bit more with the clutch done.

Unfortunately it has turned into a moneypit in short order and I don't think it's worth saving as the body is not immaculate and it seems to be chucking issues at me all the time.

I can't really afford to write off the cost though I suppose I may have to.

It is encouraging that it may carry on for a while. I might just have to run it anyway as I need to get to work...

[Futuramic]

HustleRussell said:

If it's black smoke then it could get expensive. Valve stem oil seals or even piston rings. If it's either of those things the engine will probably run fine for many more thousands of miles albeit with greater fuel consumption...

Edited by HustleRussell on Sunday 3rd February 19:51

If it is burning a bit of oil it will continue for thousands of miles if topped up. The only problem is that excess pollution is likely to destroy the catalytic converter. I'd guess that there are several on the Alfa V6 and if so it will fail the emissions test at the next MOT.

[Clivew]

I had grey/white smoke from the exhaust of a BMW 525 particularly on start up. BMW reckoned that a piston ring had broken but I wasn't convinced thinking it was more like valve stem oil seals. One dose of this and the problem was cured.
http://www.forteuk.co.uk/product.php?id=48/Seal_Co...

[BFG TERRANO]

compression test will reveal all but not valve stem seals failing. If its being a money pit give it an oil change but drop a litre of oil and use a litre of gear oil instead and get rid. Passed a few oil burners on in my teens like this, seems to mask the problem for a bit.

[GM182]

Thanks for the replies.
I'll give the seal conditioner a go and see if that sorts in out.