E46 Valve Cover: The Definitive Guide

If you landed on this page it’s because you either have an oil leak running down the side of the exhaust or front of the E46 valve cover.

On this article we’re going to take a deep dive into why the E46 valve cover and E46 valve cover gaskets leak. What parts you need to replace, what tools you need to do a replacement, and how to do VCG repair and replace the valve cover.

Plastic Valve Covers

Since BMW decided to use thermoplastic nylon valve covers on E46s back in the day for cost, and weight reductions, today thousands of E46 owners have to deal with the famous E46 valve cover and or valve cover gasket replacement.

Cracked or Warped

Built up pressure from a failed crank case valve (CCV) can cause it to crack. If you are only driving 5-10 miles a day which is not really enough to burn off all the moisture inside the system.
To diagnose this issue, look under you engine oil filler cap and you might have a yellow residue (or brown if dry). This is a sealant that BMW put on the engine bay to protect from salt damage due to overseas shipping IIRC.

Valve Cover Gasket Leak

Your valve cover gasket may be leaking for a variety of reasons.  It could be shrunken, cracked or rotten, or your valve cover itself may be cracked or broken or one of the bolts may just be lose, allowing a little leak.

This valve cover has a gasket (which is made out of rubber or cork), which seals the cover to the engine, and keeps any oil from leaking out. If the gasket deteriorates, oil will begin to leak out. If the oil leaks out, your engine will not be properly lubricated, and serious engine damage can occur.

Diagnosing your Valve Cover

Normally, you can see the crack easily but if that’s not the case, you can run a smoke test to find where there might a be crack on your valve cover.

Valve Cover Gasket Inspection

If you know the valve cover gasket wasn’t replaced before you purchased it, and you notice a leak coming from the front or the side of the exhaust, it needs to be replaced. It’s common for 1999-2006 BMW E46 3-series to have valve cover gasket leaks after 90,000 miles.

Symptoms of Wear or Failure

  • Oil coming from around the gasket
  • Oil running down the passenger (right) side of the engine
  • The smell of burning oil inside the cabin
  • Engine misfire

FAQs

What is the recommended torque spec on the valve cover bolts?

What if the old valve cover gasket turned to brittle hard plastic, and it won’t come off?

Why is it still leaking after replacing the valve cover gasket?

Why do I still have a service engine light if I’ve replaced the valve cover gasket twice?