Engine cover - what is it actually for?

jeremy156

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Mildly facetious question, I am assuming its primary purpose is to muffle noise from the engine, but I'm also curious whether there's any other purpose.

I've discovered that the engine cover is responsible for the majority of unpleasant noise from my engine - resonating as the engine vibrates. I've removed the smaller of the two covers (nearside, the one shaped to look like it's skimming the exhausts from each cylinder) and now I hear only good, engine speed/load related noises, healthy.

So, the question really is, am I doing any harm running without this cover? Is it important for keeping heat away from the underside of the bonnet?

I'm considering getting an engine blanket (http://www.noisekillergb.com/product_details.asp?ItemID=91) in place of the plastic cover - see if I can damp out some of the remaining harshness - any thoughts/warnings?
 
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jeremy156

jeremy156

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Southampton, Hampshire
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1995 E320 Coupe
That's pretty much what I was beginning to think. Very pretty, but if it makes my car sound rough, I'm best off without it.

Now clearly it does have a noice damping effect to some degree, hence my thoughts re a proper engine blanket (thin lead sheet sandwiched between foam, wrapped in a heat resistant envelope).
 

Dieselman

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Just fix the cover, the mounts will be worn out.
 

markjay

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On my W203 180K, the engine cover has a thick layer on the inner side that looks like sound-deafening material.
 
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jeremy156

jeremy156

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1995 E320 Coupe
Just fix the cover, the mounts will be worn out.
Unfortunately, since its last trip to its mechanic, one of the threads has been stripped (front nearside) and therefore the bolt doesn't pull tight - I'm not sure whether it's possible to re-tap this hole in the top of the exhaust manifold..?
 

Dieselman

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It will be. Either a larger bolt or use a Helicoil.
 

AdamG

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Bromley, Kent
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W210 E240 yr 2000 (stolen), W220 S320CDI (2003)
I added some extra sound proofing material under the cover. The laminated foam and polymeric barrier type.

It cuts down the rattle a little.

I also put some behind the engine on the false bulkhead.

Adam
 

Cabe

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Mine used to have sound deadening foam, but the previous owner appears to have ignored a leaking injector. Once it got to the point of melting onto the exhaust throwing out large quantities of white smoke (I thought she was gone for Jim!) I dont have a whole lot left any more.

Poor Jack at PCS had to clean all that muck off, which had since hardened into some kind of armour plating. He did a great job of it though.
 

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