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MG MGA - Tappet Cover Gaskets

While I have the exhaust manifold off I am doing a general clean up on that side of the engine including replacing the tappet cover gaskets. Just curious if others use gasket cement with them. My replacements from Moss are silicone.

Steve
Steve Gyles

Steve,

I have tried both the cork and later MGB silicone rubber gaskets with and without a sealing compound .

In my view a thin application of sealant is worth using.

I also replaced the bolt gaskets with the later 'B' series type


John Bray

Thanks John. My current ones were cork with Wellseal on both sides. Generally a bit grimy down the engine side after about 14 years but nothing drastic. I suspect minor weepage through the bolts during that time. That said it might have been from the rocker box cover gasket. I have the new silicone version for that also. Might go your route with the additional bolt seals.

Steve
Steve Gyles

Steve,

As we both know, it is a grimy area and it's always difficult to know just how tight (or loose) the tappet cover bolts can be secured.
John Bray

Well whatever John did it worked as they still don't leak...
David Brenchley

Pleased to hear that David
John Bray

Steve,
I use the thin cork gaskets and apply Ultra Black sealant to the cover side only. I also use a cup washer (https://mossmotors.com/cup-washer-1?assoc=191266), a rubber bushing (https://mossmotors.com/washer-sealing-3?assoc=191265), and a fiber washer (https://mossmotors.com/washer-fiber-5?assoc=191262) on both bolts. You may need slightly longer bolts to accommodate the extra parts. These items are found on the Moss USA website under MGB.

Jim
JL Cheatham

I fitted the bolt washer kit shown by John Bray above. Nice tight assembly. Many thanks.

I was wondering what the opinion is about the silicon gaskets currently supplied by Moss. The rear gasket fits very nicely as its held in place by the moulded shape of the cover. However, the front gasket seems to be critical depending on the amount of bolt tightening. My first fitting was probably too tight and the gasket tended to expand/slip outwards and I was worried that it would not hold in place over time. The photograph shows it less tight on the bolt and I am now worried that it is sufficient to have sealed it all round correctly. I have Wellseal on both sides of the gasket so keeping fingers crossed and that the bolt does not loosen. Thoughts?

Steve



Steve Gyles

I fitted the silicone gaskets a couple of months ago but they didn’t quite fit over cover. I had to reduce both ends on inside with Stanley knife and they worked fine. Has anyone else had this easily solvable problem. I don’t know where I purchased them, but most likely Moss, as they were ‘in stock’.
Steve, glad to hear you are mobile again with new knee.

Paul
Paul Dean

Paul

I ordered a pair and a rocker cover gasket. Four tappet cover gaskets arrived, 2 x thick and 2 x thin. The thinner gaskets were slightly longer and did not fit comfortably in the covers.

Steve
Steve Gyles

I fitted the silicon gaskets n request on one car, I had the same experience as Steve, and had to replace the pair with standard cork gaskets in an underground car park to get the car mobile again, I would never use them again.

In that case, both gaskets crept out from under the covers and caused oil leaks onto the exhaust, Both were tightened appropriately to the point that the covers were not starting to deform, but fully gudanteit! I also used the MGB seals and cups on the bolts. Sealant wasn't used because I don't know of anything that would stick to silicone adequately.

Stick to the cork gaskets and get the ones that fit.
Dominic Clancy

Thanks Dominic. You have confirmed my worries. It would be just another unnecessary pain to have to take off all the externals again for a weepage. Back to cork I think.

Steve
Steve Gyles

I used the Moss silicone tappet cover gaskets when I fitted the 5-bearing engine back in 2016.

I had to fit one of the deeper MGB "chest" type vented tappet cover which has a built in oil trap as well as one standard MGA tappet cover.

I seem to recall that the Moss silicone gasket looked a little small (like in Steve's picture), but I decided on a spur of the moment fix and I just stretched the seal a little until it fitted perfectly.

It must have worked because it is still oil tight after 6 years of hard use.

Cheers
Colyn



Colyn Firth

I do recommend using the MGB bolt seals and cups with the tappet covers. They remove the. seepage that is common in this area.
Dominic Clancy

For an extra measure, I put a dab of Lock-tite on the bolt threads so they don't loosen up due to vibration and heat

Cheers

Gary
79 MGB
Gary Hansen

Sealing paste and cork gasket. The paste to seal on the side of the cover. I install and give a slight squeeze to put everything in place but that the sealant is not expelled in the joint with the cork. The next day, once dry, I finally press.
Gabriel Martínez

Well, that was fiddly. The cork gasket could have done with being several mm longer. Devil of a job getting it to hold in place even with sealer. Makes you wonder what they use as a template.

Steve
Steve Gyles

This thread was discussed between 08/10/2022 and 24/11/2022

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