Mylar Hood Liner Install

If you look at photos of the intake manifold on a BMW M20 engine in an e30 you’ll see a recurring spot of wear illustrated in this older photo of my car:

BMW e30 M20 Engine Bay

This is caused by the black fibreglass hood liner which sags slightly and rubs against the manifold. You can barely see it in this photo:

BMW e30 hood liner

Also note the red tape that’s being used to protect the powder coated intake manifold which is at best a temporary solution. The permanent solution is to remove the hood liner:

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The unadorned hood isn’t ugly but it does allow more noise to escape the engine bay and some armchair mechanics postulate that the heat from the motor will cause the paint on the hood to bubble or wear poorly.

There’s two solutions for this:

  • BMW makes black foam insulating panels for some models but enthusiasts report that it falls apart after a few years of use and soaks up oil and grime. Part numbers are not noted on RealOEM but the set is available.
  • The other solution is mylar covered foam.
  • I bought my panels from BMP Design. They have a complete DIY on how to install the hood liner which is helpful.

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    Now a few comments about the product:

    • It’s recommended that you “test fit” the panels before installation. Once the contact cement is applied you really only get 1 shot at installing the panel so plan how you will place it (which end will go in first, etc.)
    • You may find that the panels do not fit exactly. I suggest *returning* them if they don’t fit. I tried to cut mine with a ruler and knife, then scissors and it is very difficult to cut cleanly.
    • Even if your panels fit you will find ragged edges where the mylar has been torn. Clean these up with scissors before installing.
    • The panels come with an adhesive backing. This is not strong enough to affix the panels without contact cement.
    • No fault of the product, but it does tend to show wrinkles if not applied perfectly flat on a surface. The e30’s hood has some bends and curves so some wrinkles are inevitable.

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    Installation was straightforward once I trimmed down the panels:

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    • Cover the entire engine bay in plastic.
    • The Weldwood adhesive is supposed to be workable for about an hour after application – if it’s applied thickly. I decided to apply it thinly using a foam roller which made application quick, although the roller produced some spider-webs of contact cement that had to be tamped down or pulled away from other surfaces. This saved time but also reduced workability to seconds once the panel and the hood were contacted.

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    BMW e30 m20 engine bay with BMP Design mylar hood liner

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    August 26, 2013 guide, mechanical