Lotus Elan

Oil Tight Cam Cover

PostPost by: AndyBott » Thu Jul 08, 2004 12:46 pm

:( Any suggestions greatfully received on achieving an oil tight seal, which lasts, on the cam cover. I have owned a 1973 DHC Sprint for the last 4-years and have never managed to get a year long seal. I do the appropriate cleaning and preparation when re-sealing and torque tighten as appropriate. I am down to cleaning/de-greasing after every outing ! Is seallant the answer ? If so what type?
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PostPost by: steveww » Thu Jul 08, 2004 2:02 pm

Make sure both surfaces; head and cam cover are clean and smooth, fine wet and dry works well. Apply a thin layer of silicon sealant to the cam cover then place a new gasket on to this sealant and position carefully. Place gasket side down on workbench and add a couple of kg of weight, I use a couple of old front disks. Leave overnight.

Apply a thin layer of silicon sealant to the head. Place cam cover + gasket on to head and torque up. Use new selock (sp?) washers.

This has worked for me :D

NOTE Only use a minimum of silicon sealant as you do not want stray lumps of sealant working round the engine and blocking something important :o
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PostPost by: john.p.clegg » Thu Jul 08, 2004 3:00 pm

My way is as follows:-
1) clean both mating surfaces.
2) apply a thin coating of oil to the head.
3) turn the cam-cover upside-down and apply a thin bead of silicon sealant to the mating surface
4) now place the cam-cover on the head held down by its nuts BUT do not tighten them(a gentle pressure just to seat it).
5) leave overnight to cure.
6) there should now be a re-usable silicon gasket attached to the cam-cover which should be a perfect match to the head mating surface.

Mine lasts for ages
John
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PostPost by: type26owner » Thu Jul 08, 2004 3:24 pm

Not exactly sure which bits are leaking since there are three problem areas. If it's the cork gasket then I suppose there might porous ones available which will leak if the air pressure inside the engine is excessive. Even running synthetic oil I've had no leaking from the large cork gasket and that's using no sealant on it. The problem I think comes from sealing the eight cam cover studs poorly. If you install a compliant seal under the nuts on the studs then you've tuned the lid to lift up slightly under very small pressure gradients like when the engine is at WOT. There are many square inches of surface area under the cover which allows a small pressure load to exert a tremendous load onto the sealing washers under the nuts cyclicly loosening the clamping force on the cork. It's going to leak eventually no matter if it's glued together or not. To eliminate this effect the sealing system for the studs MUST be done from the inside of the cover so there is no cyclic cover motion. This puts the combined forces of the two type gaskets to be exerted in the same direction against a stiff structure. I cut 1/2" long pieces of hydrocarbon resistant 1/4" ID fuel hose and slip those over the studs. This leaves just an 1/8" gap to crush the hoses down until the cork gasket is crushed too. Pull the cover down evenly crushing the cork by 30-50%. No sealant is required but I do apply contact cement to the cork gasket and the cover and stick them together just to make assembly process easier. It won't leak there anymore if the engine has adequate crankcase venting. Preferably the cork and the stud hose gaskets are replaced with new ones after every cover removal. In a pinch the cork can be reused. Never try that with the stud seals though.
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-Keith
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PostPost by: poiuyt » Thu Jul 08, 2004 3:35 pm

Just had the engine rebuilt and the cover was leaking from everywhere. When it came time to re-torque the head the following wass done:

1. Got a tube of the GREY RTV (the one that says for foreigh cars) at PEP Boys and put a small bead all around the top of the head - including where the rubber half moons go.
2. Put in the half moons and the ckrk gasket
3. Put another small bead of the RTV on the top of the cork gasket.
4. Installed the Dave Bean oil shield on the bearing studs under the oil cap - this keeps oil from coming out of the oil cap
5. Installed the cam cover and put a small amount of the RTV on the washers under the nuts

No leaks from the cam cover. Still have one small leak from somewhere else that I'm trying to find.

Steve Becker
:D
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PostPost by: AndyBott » Fri Jul 09, 2004 11:57 am

:D Thanks for all the suggestions. The oil shield and stud hose gaskets are great tips. I think I will go for a mix of various suggestions (incl poss sealant but may try without first). I will let you know what works for me.
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PostPost by: type26owner » Fri Jul 09, 2004 4:08 pm

Andy,
Let me give you another tip. The original oil filler cap has a problem which causes it to leak. The oil shield probably does not fix this problem it just reduces the volume. The springs on the cap which engage the lugs in the cam cover as an assembly are poorly designed. If you measure the distance between the lugs and compare that with the distance to the outside edges of the springs you'll find they only overlap by about 1/16" total. The cap seals just fine if it's centered perfectly and both springs are engaged onto both lugs. The problem is the amount of sideways slop is excessive so it never gets centered upon installation and the cap will tilt up on one side and lift off the sealing gasket. I built a close fitting spacer which snaps into the cap to fill up the sloppy play and centers the cap to the cylindrical boss of the cover. A simple spacer fixed that problem.
Regards,
-Keith
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PostPost by: steveww » Fri Jul 09, 2004 4:30 pm

The cap has a rubber sealing ring. To ensure a good seal on the cap I just installed 2 of these rings rather than the usual 1. Works for me :D
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PostPost by: AndyBott » Mon Jul 12, 2004 11:21 am

:D Thanks - Steve & Keith I will try both further suggestions
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PostPost by: miked » Mon Jul 19, 2004 12:50 pm

John (mrjxc09),
I read all the comments on this subject. I am having problems on my S4 with this leaking from the cam cover gasket. I have had numerous attempts with Welseal. etc, etc. I have come to the conclusion that my leaks are through the actual cork. The gasket is made up of two pieces and has a foil in between. I supsect it come through the foil but it could be through the cork.
I notice your way of doing it. Am I right in thinking that you ommit the cork (altogether) and use the formed silicon as the gasket!? I have toyed with this idea.
My engines has its breather to the air box for cleanliness and odd whiffs of the engine. This being factory spec', I would have though it is ventilated correctly. The engine is a fresh rebuild and runs sweet. No great blow by gasses etc.

I wonder as with other Lotus bit, Is the gasket not as good as it used to be. My old Plus two (5-6 years ago) would seal with the gaskets I used.

regards Mike
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PostPost by: worzel » Mon Jul 19, 2004 2:11 pm

I can only speak personally but I've never had a problem just using the cork gasket and I only use copper washers under the the cam cover fixing bolts. As a suggestion what type of nuts do you use- are they the domed type or ordinary nylocs?. If domed it might be that too much thread is protruding throught the cam cover which means the nuts go tight but don't actually "nip" the gasket. If so add extra washers or try oper ended nuts. I use stainless domed ones and have to add spacers for them to work. Might be worth a try

John
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PostPost by: worzel » Mon Jul 19, 2004 2:12 pm

I can only speak personally but I've never had a problem just using the cork gasket and I only use copper washers under the the cam cover fixing bolts. As a suggestion what type of nuts do you use- are they the domed type or ordinary nylocs?. If domed it might be that too much thread is protruding throught the cam cover which means the nuts go tight but don't actually "nip" the gasket. If so add extra washers or try oper ended nuts. I use stainless domed ones and have to add spacers for them to work. Might be worth a try

John
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