Lotus Elan

Cometec cam-cover and sump gaskets

PostPost by: Foxie » Tue Oct 04, 2016 11:44 pm

After 30 years using the standard double-cork-and-foil sandwich gaskets, using gasket goo on one side and oil on the other, I got fed up replacing them as they came apart whenever I removed the cam cover or sump.

So recently,when assembling my rebuilt engine with a new block and alloy dry sump, I ordered a set of Cometec gaskets. Again, I assembled with gasket goo on one side and oil on the other.

When I started up the engine, the oil was not oozing from the cam cover, it was actually spraying out :-o

So I removed the cam cover, and on visual inspection saw there was some distortion. I replaced it using a new cork gasket, and hey presto, perfect seal.

Checking the sump, there was considerable weeping along the joint just under the oil pump. Tightening up the 1/4" cap screws considerably over their recommended torque eventually stopped the leak.

So, even though the cork gasket breaks up on disassembly, it does seem to give a much better seal :)
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PostPost by: gjz30075 » Wed Oct 05, 2016 9:16 am

How flat is the mating surface of the cam cover? I, too, tried the cometic cam cover gasket and found it
simply wasn't thick enough to take up the very slight warpage the cover had, and hence, leaked. The cork gasket was thicker and did the trick.
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PostPost by: Maulden7 » Wed Oct 05, 2016 9:26 am

Perhaps I've been lucky, but I fitted one of these a couple of years ago & it has been perfectly oil tight.

The only place I used any additional sealant was around the "D" plugs.
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PostPost by: Foxie » Wed Oct 05, 2016 6:52 pm

gjz30075 wrote:How flat is the mating surface of the cam cover? I, too, tried the cometic cam cover gasket and found it
simply wasn't thick enough to take up the very slight warpage the cover had, and hence, leaked. The cork gasket was thicker and did the trick.


The cam cover has visible warping. Will go to my machine shop for surfacing next time it comes off. :)
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PostPost by: Grizzly » Wed Oct 05, 2016 6:59 pm

Before you start machining the Cam cover check the head side is flat, mine is low across the front edge (the flat between the two front D's) so it still leaked even after i had the Cam cover refaced. Even after allot of messing about i still ended up with a Burton Cork gasket.
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PostPost by: Foxie » Wed Oct 05, 2016 11:09 pm

Grizzly wrote:Before you start machining the Cam cover check the head side is flat, mine is low across the front edge (the flat between the two front D's) so it still leaked even after i had the Cam cover refaced. Even after allot of messing about i still ended up with a Burton Cork gasket.


The head was stripped, pressure tested and service skimmed last month. It's good.

The cam cover is visibly warped, that is where the problem is ! :)
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PostPost by: rgh0 » Thu Oct 06, 2016 9:59 am

The top of the head can become warped overtime as the bottom is re-machined to keep it flat due to head distortion. This machining locks in the distortion on the top.

This can lead to problems with cam tunnel alignment and flatness of the cam cover gasket face.

If you ever have the face of the head machined to get it flat you also need to check the top face and cam tunnels. Most people and most machine shops don't bother with this.

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PostPost by: Grizzly » Thu Oct 06, 2016 10:11 am

Foxie wrote:
Grizzly wrote:Before you start machining the Cam cover check the head side is flat, mine is low across the front edge (the flat between the two front D's) so it still leaked even after i had the Cam cover refaced. Even after allot of messing about i still ended up with a Burton Cork gasket.


The head was stripped, pressure tested and service skimmed last month. It's good.

The cam cover is visibly warped, that is where the problem is ! :)

I'm not arguing with you i'm just saying it's some thing you need to check. As Rohan said the fact you had your head skimmed would make it even more important to check simply because if that face has distortion it's likely the cam cover surface will too. Thats without taking into account the Cam cover has got hot enough to warp.
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PostPost by: Foxie » Thu Oct 06, 2016 12:34 pm

Grizzly wrote:I'm not arguing with you i'm just saying it's some thing you need to check. As Rohan said the fact you had your head skimmed would make it even more important to check simply because if that face has distortion it's likely the cam cover surface will too. Thats without taking into account the Cam cover has got hot enough to warp.


I take your point, it's a good policy to check. It's now on the job-list ! :)
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PostPost by: prezoom » Thu Oct 06, 2016 3:54 pm

I went through this nose bleed with a warped cam cover when I first purchased my Elan. After several attempts at sealing the leaks, I decided that the gaskets were not the problem. Used my lapping plate to identify the high and low spots on the mating surface of the cam cover, did a thorough cleaning of the mating surface, applied JB Weld to the low spots, spread some clear plastic wrap, tightly to remove wrinkles, on a flat surface, placed the cover on the wrap and weighted it down until the epoxy cured. Replaced the wrap with about six sheets of abrasive paper, glued down with spray adhesive, and moved the cover over the abrasive in a figure eight pattern until there were no high or low spots. Leaks cured with a new cork gasket. Still good after almost 10 years.
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