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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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Old 11-24-2012, 09:44 AM
ventsyv ventsyv is offline
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Diagnosing a VCG leak

I was having a pretty massive oil leak which I traced to the area under the intake. I had the PCV replaced along with all the hoses from the kit, as well as the oil filter gasket.

The rate of oil loss was reduced, but not completely eliminated. After inspecting the engine bay for traces of fresh oil, I found some on the metal trim on the passenger side that shows below the plastic covers.

I suspect I have a leaking VCG. The car has 130 000 miles and is still on the original VCG, so it's not a surprise that it leaked, but is there any way to confirm that?

I replaced the spark plugs about 50,000 or 60,000 miles ago. If the VCG leaked, do I need to replace the sparkplugs? If I remember correctly, there are little gaskets for the plugs, right? Chances are they went bad too right?

Last edited by ventsyv; 11-24-2012 at 09:58 AM.
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Old 11-24-2012, 02:01 PM
QAfred QAfred is offline
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If that aluminum heat shield you refer to has oil residue on it you just confirmed the VCG has an oil leak. Look your parts up on realoem and you can see the illustrated parts breakdown (IPB), for your model.

The new VCG will also have the gaskets that seal around each spark plug included, but the rubber washers, that go under each bolt, should also be replaced since these are what push down on the cover to seal it. The VCG bolts bottom out when tight so be careful not to overtoque and break them, in this case when the stop turning they are as tight as they are going to get- so stop, and with new washers you will seal better and may not bottom out.

You do not necessarily need to change plugs just because you are changing a worn / leaky VCG.

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Old 11-24-2012, 10:43 PM
GoForthFast GoForthFast is offline
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Spark plug hole gaskets come with the kit, so replace them all at the same time.
But they rarely leak.
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Old 11-25-2012, 07:17 AM
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Scottji Scottji is offline
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A telescoping inspection mirror, which should be mandatory for any garage, will assist you in diagnosing the VCG leak. Get the mirror and a flashlight, and check along the bottom edge of the exhaust side of the valve cover. But as QAfred said, the fact that you found oil on the metal flange strongly suggests VCG leak.
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