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BMW and MINI Oil In Spark Plug Tubes, Wells – Valve Cover Gasket Leak – How To Fix

May 22, 2012

This answer is applicable for many BMWs in addition to the one listed below.

1995 525i
Hello Otto, hope all is well.
I was recently watching your DIY video on replacing Coils And Spark Plugs after I went over to my car to check my coils and spark plugs only to come find out that they are FLOODED in oil (please see picture attached) now I know that this isn’t normal at all because it doesn’t look anything compared to your video. Looking at the pictures attached can you please tell me what I need to buy to get this fixed. It’s for the 525i 1995.

Note oil covering the lower few inches of the spark plug boot - resulting from the spark plug well filling with oil due to leaking valve cover gasket

What we have here is a text book example of a leaking valve cover gasket.  The twin-cam BMW and MINI engines not only have the standard gasket around the perimeter of the valve cover, but they also have gaskets that seal the valve cover to the spark plug wells.  When these gaskets fail and start to leak (notice we did not say “if” they leak), the spark plug wells will begin to fill with oil. This not only makes a mess, but can cause engine management problems, such as cylinder misfires.  Additionally, the oil will destroy the insulating capabilities of the spark plug boots.

When we find this condition, it’s time to replace the valve cover gasket set and the spark plug boots (the boots should be changed whenever the spark plugs are changed, either way).

Click the link below to see a DIY on replacing valve cover gaskets on the BMW 4, 6 and 8 cylinder engines from the early 1990s through the mid 2000s.  These include the M42, M44, M50, M52, M52TU, M54, M56, M60, M62, S50, S52 and S54 engines.  The DIY is done on an M62 V8, but the procedures are similar for the other models.  Additionally, the Bentley repair manuals will cover each model in detail, as to the valve cover removal and installation.

Click below for the Fall 2009 issue of our Fast Times newsletter, and the Valve Cover Gasket how-to DIY article:

Bentley repair manuals:

Valve cover gaskets:

Spark plug boots:

Rubber Gasket Sealant (as shown in DIY & Bentley manuals):
Permatex 86409 rubber gasket sealant and dressing

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