Rubber gasket for cam covers

[Cos]

Hi guys

Some bloke on eBay is selling rubber gaskets for lotus 900 series engines. Seems like a good idea, but has anyone actually fitted any? He says in his description that the covers have to be straight.

I imagine that they should be made of a soft silicon if they are to make a seal between 2 cast surfaces.

[Guest WausauLotus]

There is another thread on here somewhere that was talking about routing in an O ring groove in the cam covers and then using an O ring to seal. Sounded like a good idea to me........Thoughts

[andydclements]

The rubber ones are used very successfully by Jensen owners which share the saddle sealing issue. The difficulty comes with a previous owner over-tightening the bolts and distorting the saddles, after that they refuse to seal well.

[Cos]

I see. So they seem to have worked. They o ring groove sounds like a good idea too. But I imagine that the covers again need to be perfectly straight or else they will leak.

Has anyone had any bad experiences with the rubber seals available yet?

[Sir Paolo]

I've bought them but, I've yet to fit them.

I have heard about gluing the enges down, but a more suitable method of securing them - until the bolts have been tightened down enough is to use duck tape.

Tape over just enough of the gasket that you can prise the tape away, when the bolts are apporaching final torque.

Also make sure no oil is present, as this will ensure leaks.

[Tony K]

I tried the black rubber (neoprene, I think) gaskets about ten years ago. I don't think they are bad, but here's why I prefer the original fiber gaskets and a thin smear of sealant:

- The rubber gaskets were more difficult to install - messing around with little pieces of tape so they don't move out of place was fiddly, and there was, in my opinion no benefit in the end of using the rubber gaskets (i.e., they don't seal better or longer).

- Regardless of which gaskets you use, you will have to re-snug the six cam cover bolts after several engine heat cycles (i.e. a week) and after a season or year. In the time before that, a little bit of oil is going to seep between the gasket and mating surfaces, rendering useless all that time you took to make them squeaky clean, and encouraging drips. People tend to put the disclaimer of "the surfaces have to be free of oil in order for the rubber seals to work" before their praise of the rubber gaskets; well yes, of course! If people actually put that same effort to properly clean and seal the surfaces when using the original gaskets, they would find that the originals will last quite a long time before seeping, and, as the cam covers are "glued" to the housings with the sealant, they are less likely to seep when everything is cold and the bolts need to be re-tightened.

- The rubber gaskets I used started to harden after a couple thousand miles. Not much, but they had nowhere near the elasticity that they did when I installed them.

- Doing it the original way (fiber gasket with small amount of black sealant) looks more original from a concours perspective.

Just my .02

p.s. -- never tried the newer reddish- or beige-colored rubber gaskets, but I don't see how they could be much better. Once serviced a car whose profusely leaking cam cover gaskets were made of cork . . . don't even bother with that!

- T