Engine sealants

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richardw
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Engine sealants

Post by richardw »

I have a few copies of a magazine called Elite Lotus published in the early 90s. In the Winter 1992 issue is this piece by Miles Wilkins detailing which sealants should be used on Lotus engines. Given the extensive discussions about sealing 907 cam covers, maybe this is of some interest:

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Pete Boole
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Re: Engine sealants

Post by Pete Boole »

Good post Richard. Although the article calls them cam covers what they are actually talking about is cam housings - the bit under the cover.

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richardw
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Re: Engine sealants

Post by richardw »

Thanks Pete - it does specify Silastic for the covers in the list for the 2 litre engines, although the article itself talks about the cover to head seal.

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robertverhey
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Re: Engine sealants

Post by robertverhey »

Depends which type of 9 series motor we’re talking about. Both use permaseal for cam carrier to head joint, which compresses to a pre-determined thickness. As for the cam covers, early 907 saddle types need a sealant like silastic, but the later 912 types don’t need any sealant in my experience, just the gasket fitted dry.
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Re: Engine sealants

Post by AndyC »

I thought Lotus moved and started specifying Loctite zero thickness sealer for the cam carrier-head joint.

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robertverhey
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Re: Engine sealants

Post by robertverhey »

Sorry my bad, Not permaseal, For cam box to head, I use permabond A136 /loctite 504 or equivalent. The red stuff. It’s not quite zero thickness, from memory you need to do valve clearance shimming “dry”, compensating for its minimal thickness when you do the final assembly.
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Re: Engine sealants

Post by AndyC »

Yep that's the stuff, they call it zero thickness but as you rightly state it isn't. When I've pulled them apart there are places that seem to be almost devoid of sealant, so I guess it can be a thou' or less in places which is a darn sight easier to allow for than a paper gasket that used to be specified in early engines.

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