Silicone Base Gasket

[Paulcars1]

Hi Ian Thats good enough for me to stock them here in NZ and use them

[Ian Dunford]

I have fitted a good number now (possibly 20-30) all have been 100% successful in my experience.

Faces must be completely clean prior to assembly, I leave the block for 24 hours before setting the tappets to allow for settlement.

This rumour sounds like a classic case of somebody with an axe to grind or just as likely a possibility of not following the proper fitting instructions.
My own has been in place for some years now and is extraordinarily suceesful.
I now no-longer need to take 5 extra gallons of oil on continental excursions.

[Ray White]

This is what I have been using of late. Good stuff.

[Ian Williams]

Ray, from my own experience of the block to crankcase joint you will have greater success with a silicone gasket of the type the Seven Workshop sell, you will also have less chance of a bead of the Permatex sealant blocking a jet or oil way. I have tried most things over the years, paper gaskets are guaranteed to leak, silicone gloop is reasonably successful but there are risks and it will eventually leak, 518 works reasonably well for a while but again will leak eventually. As mentioned the vital thing if using a sealant or silicone gasket it total removal of oil or contaminates from the joint faces, for most other joints I have compete faith in 518 or Hylomar, both are very good products and you will not get hard globules of silicone gloop blocking anything vital.

[Colin Cheesman]

Ian, I am having a new engine built for a 32 Roadster I am building, body nearly complete. I am planning to use a silicone gasket, so this thread is very timely. I am interested in any specific instructions for using the gasket, if there is any. 

Thanks Colin

[Ian Williams]

Well Colin Rory is probably the man with most experience of fitting these so I am sure he will comment if there is anything I have missed or that he disagrees with here. The main thing as already mentioned is cleanliness, I use brake cleaner to ensure there are no traces of oil or grease, and as with any joint check the faces are flat and free from burrs. Tighten the base nuts down evenly a bit at a time, diametrically opposite much like you would on a cylinder head, once tight you will find the gasket has spread a little as it compressed, I trim any excess with a craft knife. As Rory mentioned in his earlier comments, recheck all nuts after leaving it to settle overnight, but thats it I can not think of anything else to be aware of.

[Ruairidh Dunford]

Sound and comprehensive advice, as ever, Ian.

[Dave Wortley]

I am probably being a bit thick here but can someone explain the need for scrupulous oil/grease removal from the gasket faces please.

[Ruairidh Dunford]

If the faces are not clean and dry Dave the gasket slides out when compressed.

[Colin Cheesman]

Well Colin Rory is probably the man with most experience of fitting these so I am sure he will comment if there is anything I have missed or that he disagrees with here. The main thing as already mentioned is cleanliness, I use brake cleaner to ensure there are no traces of oil or grease, and as with any joint check the faces are flat and free from burrs. Tighten the base nuts down evenly a bit at a time, diametrically opposite much like you would on a cylinder head, once tight you will find the gasket has spread a little as it compressed, I trim any excess with a craft knife. As Rory mentioned in his earlier comments, recheck all nuts after leaving it to settle overnight, but thats it I can not think of anything else to be aware of.

Thanks for the great advice Ian, brake cleaner seems like a great tip. My crankcase has been skimmed so it will be nice and flat.