Smoke from exhaust/milky gunk under oil filler cap

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Scylla
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Smoke from exhaust/milky gunk under oil filler cap

Post by Scylla » Sun Jun 19, 2011 7:10 am

Title says it all, really. White smoke at idle, not billowing but noticeable, and this milky goo inside the filler cap which I've not seen before. Type 4 2.0 FI. Is this a very bad thing? What do I need to do?

Thanks as always -

Damian

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satchmo
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Re: Smoke from exhaust/milky gunk under oil filler cap

Post by satchmo » Sun Jun 19, 2011 7:41 am

Scylla wrote:Title says it all, really. White smoke at idle, not billowing but noticeable, and this milky goo inside the filler cap which I've not seen before. Type 4 2.0 FI. Is this a very bad thing? What do I need to do?

Thanks as always -

Damian

It usually means you have some water or highly humid air going into your engine and that your engine/oil rarely gets hot enough to evaporate the water. So you end up with a frothy mix of oil and water on top of your oil that collects in certain places, like the oil filler tube and cap, the breather chimney, etc. This happens to everyone in the winter who does trips in the bus that are so brief that the engine doesn't have a chance to warm up, but could conceivably happen in the summer too if you don't get the engine hot. You should also look for any possibility of water in your gas tank.

Tim
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

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RSorak 71Westy
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Re: Smoke from exhaust/milky gunk under oil filler cap

Post by RSorak 71Westy » Sun Jun 19, 2011 9:37 am

The white smoke is actually probably light blue and is oil smoke.

The explanation of the sludgy stuff is right on.
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Rick
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Re: Smoke from exhaust/milky gunk under oil filler cap

Post by vdubyah73 » Sun Jun 19, 2011 10:02 am

where are you? is it still cold and raw in the AM? the goo in the oil answer is correct. either answer for the smoke could be correct. I'm sure you've been behind a car in the morning or in cold and humid weather that has a liquid pouring out the exhaust pipe, that liquid is water that has been squeezed out of the humid intake air by the engines compression and combustion. You have to determine if the air has the humidity to suggest it is water.
if your car is smoking and you see some other cars pouring water out the exhaust it is probably water vapor. Traditional front engine cars have much more exhaust pipe to warm up than a rear engined VW. A VW will smoke white vapor much sooner than others because of this. The cold pipe reaching from front to back condenses the vapor to water longer than the quickly warming short exhaust of an ACVW.
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Scylla
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Re: Smoke from exhaust/milky gunk under oil filler cap

Post by Scylla » Sun Jun 19, 2011 10:20 am

I'm in North-East England where it's wet and cold at the moment... noticed the smoke after some stop-start driving a few days ago, then again today after a 35-mile stretch. If it's oil smoke, what steps do I need to take? And if water, how is getting in there?

I appreciate the replies. Am I OK to carry on driving the bus?

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Amskeptic
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Re: Smoke from exhaust/milky gunk under oil filler cap

Post by Amskeptic » Sun Jun 19, 2011 10:29 am

Scylla wrote:I'm in North-East England where it's wet and cold at the moment... noticed the smoke after some stop-start driving a few days ago, then again today after a 35-mile stretch. If it's oil smoke, what steps do I need to take? And if water, how is getting in there?

I appreciate the replies. Am I OK to carry on driving the bus?
It is not necessarily "smoke". It is likely to be combustion vapor. The water is getting in there from the chemical reaction of gasoline and oxygen. Perfect combustion leaves only carbon dioxide and water.

If it is exceptionally humid and chilly, you will see water vapor clouds coming out of the exhaust the entire time the engine is running. So will most other cars running rich and cool. And the jets up in the sky will have pretty intense contrails.

If you want to ascertain oil smoke, you have to pick a warm low humidity day with a very well warmed engine. Observe the tail pipe on slow speed deceleration followed by acceleration as you follow your bus (or have someone else do the observing while you drive).
If blue smoke on decel, valve guides is the usual culprit.
Blue smoke on acel, piston rings.
You can smell oil smoke. Confirm by pulling every plug on a cool engine and looking for oily wet. If all plugs are dry flat black on the outer perimeter with whitish/tannish center electrode, it ain't oil smoke!
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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