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Discussion Starter #1 (Edited)
For anyone who may have replaced the lower cam carrier gaskets, I was wondering if you could tell me the make up of the gaskets. Is it a paper type gasket, or like a plastic type gasket. The reason im asking is, mine have been leaking as long as I owned the car, and although it doesnt seem to affect the operation of the car as it uses little oil, the car smells like burning oil when I bring it back from a run and im positive its these gaskets. I am pretty proficient in making my own gaskets and I have already made and used my own upper cam cover gaskets, plenum gaskets, intake manifold gaskets and thermostat gaskets from gasket material I got at NAPA. I was just wondering if it was possible to use the same paper/fiber matierial to make the lower cam tower gaskets as well. I cant see why it would make a difference really, but figured maybe someone can give me a heads up on the material Lotus uses. Im at the point now where I can do that timing belt in my sleep so figured solving this problem wont be such a big deal now if I can easily come up with the gaskets. Or are these gaskets just Orings?
 

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Loctite 518 (or 5188) or Permatex anaerobic gasket maker.

It is thin so it doesn't effect your valve clearance measurements. Any other material will effect the valve clearances, and require different shims. A paper gasket would make a huge change!

The anaerobic sealant squishes to ~.0005" thick.
 

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I can't lay hands on it at the moment but I think the deletion of the paper gasket is covered by a service bulletin quite early. Ive never had one leak since I stopped using the gaskets and everytime I think it is leaking it turns out to be something else. Often the seals on the screw in covers over the cam tower retaining bolts. The original gaskets are of the thinnest brown paper.
 

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The paper cam tower gasket was never used on the Turbo engine, possibly because the heat from the red hot exhaust manifold would cause it to it burn and catch fire (not good).

The original "liquid joint" gasket maker Lotus specified was Loctite 504, which was later superceeded by the 515 type, both are "anerobic" gasket compounds which actually seal in the absence of air.

I have found however that If your cam tower is slightly warped (usually through overtightening), the thicker 504 still has the ability to seal an slightly imperfect joint, when the thinner 515/518 types may not be able to.

When using these products the faces of the top of the head and the base of the cam tower have to be scrupilously clean, and they are also sensitive to humidity which may affect the seal, so a dry warm environment is a must.

I read somewheres that Permitex Aviation Form a gasket also works well, never used it on a Lotus cam tower myself, but it may help create a seal where the Loctite anerobics wont.

Its worth putting an engineers straight edge on the face of the cam tower when you have removed it to make sure its perfectly flat, alot were warped by mechanics that overtightened the bolts that hold them down in an attempt to stop oil leaks.

I just want to add that since Loctite 504 appears to be no longer availible the only alternatives are 515/518 , I bought a large tube of 504 years ago ($100!) and seem to have enough left for a lifetime.
 

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Discussion Starter #5
Anybody happen to have a photo the the engine with the cam carriers removed? Im just curious what the surfaces look like before I tackle this.
 

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Underside of cam carrier. note brownish sealant (old Loctite 518)


Before removing the cam tower, you should place magnets on the tappets to hold the shims... Otherwise the shims will go everywhere and you won't know which went where.
Magnets in ziplock bag



The cam towers are held on with male TORX bolts (you will need a thin walled femal E-10 socket to fit down the holes in the cam towers.

And to prevent rounding off the bolt heads, you should use a long bar and make sure to steady the socket with one hand, like this.


The top of the head, where the cam towers mount, looks like this.

Or like this when clean.

Clean the entire underside mounting surface of the cam, and the surfaces of the head.


Smear the red Loctite anaerobic adhesive on the cam (this is actually too much)

The sealant flows easier if you place the tube in hot water (it cures in the absence of oxygen, when the metal gap is tight)


Make sure to check your valve clearances before you remove the cam towers (write everything down). Then reassemble the cam tower dry with shims and measure again to figure out what thickness of shims you will need for each tappet. Then reassemble the correct shims in place with Moly grease. then put sealant on the cam towers, or head surface and reassemble. Also make sure to tighten in the correct sequence.

Here are the shims


If you are checking valve clearances, with the cam on the head, you should turn the crank to 90 deg from TDC so the valves don't hit the pistons.
 

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Loctite 518

Loctite 518 has been superseded by Loctite 5188. I have had very good outcomes with using 5188 on the cam tower joint. However, 5188 is hard to find. A lot of the owners on this list have used 518 very successfully. I would advise against using any kind of paper or other gasket for the can tower/head interface. If you clean the surfaces well you can get a very good result using an anaerobic sealant. I would think a gasket will give you problems in terms of your valve clearance settings and on the exhaust side will also be subject to some extreme temperatures. I have never seen a 910 engine which had gaskets on the cam tower/head joint.
 

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Don't use an activator with the 518 on the cam towers though as it will kick off and begin to harden before you can get the towers torqued down and play havoc with your shim settings. Been there, done that.

I agree with Tom on the 5188, great stuff.
 

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Discussion Starter #11
Thanks for all the help and photos especially. Im gonna take on this project in the next few weekends, since I know I won't have to wait for parts I am especially looking forward to performing it.
 

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If you are going to check your valve clearances at the same time, which would be recommended, then be aware that if any need adjustment, you will need to get new shims. You won't be able to order new shims until you know what size to order, and you can't know that until the cam carrier is off......because the existing shim size varies from valve to valve.

Also sometimes the existing Torx bolts are prone to having their heads strip, so be very careful and use a properly fitting socket. JAE offers a replacement set which have a more robust head design.........and when replacing the cam carrier bolts it is very easy to strip the holes in the head if you are not extremely careful to thread them correctly and then not over torque.

The whole process is very precise, tedious, and prone to screw ups. We have done it several times with the engine out. Never tried it with engine in, but would be much harder, especially for the exhaust side.

Not trying to discourage you, just educate. Don't do this if you must have the car running the next day, give yourself plenty of time, and be aware this is one of the more difficult procedures you can do on this motor

Randy
 

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Resurrecting an old thread....

Where do you buy an E-10 thin wall torx socket? I assume 3/8" drive?

Thanks,
Bob
 
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