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Gasket sealant?

Submitted by keith_brown on Thu, 26/07/2012
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Commando

I have my 71 Norton engine back in the frame and am about to start replacing covers. Most of these have waxed paper gaskets; when rebuilding car engines I used to smear these with Hematite red or hylomar blue gasket sealant. Anyone any thoughts on this? Or suggestions as to what may be a better product to use. Maybe just assemble them dry?

Submitted by Anonymous (not verified) on Thu, 26/07/2012

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Keith,

You have plenty to choose from, but please avoid Red Kryptonite - it is a work of the devil. I didn't know you could still get hold of it and I hoped it might have been banned.

I was brought up to glue one side of the gasket and grease the other in case it had to come off. For the glued side, Hylomar is not what it used to be but still good. I am also a believer in silicone; others are not. As regards grease, try e.g. a lithium type that does not go runny when hot, especially around the engine parts.

Look also at the silicone rubber gaskets for the rocker covers. These used to originate from Rocky Point in the USA and I don't know if anyone is selling them over here. Just over finger tight on the rocker cover nuts is then all it takes to get a seal.

Something makes me think this discussion might go the same way as the threads on oils. Do we have any dry gasket purists out there? Stand by for a whole range of opinions !!

Submitted by keith_brown on Thu, 26/07/2012

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Thanks for that Chris. I assume by your comments that if you can use lithium grease on one side and it seals, the same would apply to greasing both sides. Your comment about the rocker covers is interesting, it sounds as though they may be a little tricky to seal. I have seen photos of the nuts there wired. I guess they must be prone to unscrewing themselves. I have also read somewhere about high temp silicone sealant that will keep the exhaust nuts in place, so maybe your silicone suggestion is the way to go. Decisions, decisions, sometimes there are just too many options.

Thanks for input though, I now feel comfortable with three options and maybe a dab of silicone on the rocker cover nuts.

Submitted by dave_graham1 on Thu, 26/07/2012

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I've always used Hylomar Blue, but lately I've been unable to get it. The only gasket sealer I've managed to find is silicone. We always used to call it gorilla snot, as when you took a casing off it was stringy and everywhere. The thought of a strand breaking loose and clogging an oil way was worrying. If you use silicone wet, you glue the casing on and it's a sod to get off. So I very lightly coat the gasket with it on both sides and let it set hard. Then grease one side. The casing seals without stringy bits everywhere and comes off with the gasket intact (usually). If I don't have a gasket, I put a smear of silicone on the removable casing and let it set. Then grease over the top. This makes a silicone "O" ring and the casing is still removable. The trick with it is to use it sparingly.

Submitted by john_shorter on Fri, 27/07/2012

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Hi Keith, So far, no one has mentioned the exhaust rings. Don't use any form of silicon on these, they get far too hot. I don't know if it is still available, but, there used to be a product called "Copper Coat", this was produced as a grease, and in an aerosol can, one can may last a lifetime (if you don't loose it!). This product is good for exhausts, plug threads, and smearing on engine nuts & bolts before reassembly. I had a '71 Commando, until recently, there was never a problem with the rocker covers leaking (likewise with my '54 Dommi). John.

Submitted by Anonymous (not verified) on Fri, 27/07/2012

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After years of fiddling around with springs and tab washers, I now use a silicone product Loctite 5920 for fixing the exhaust rings. It has a phenomenal temperature rating of up to 350?C, discolouring slightly at cylinder head temperature but remaining intact. In fact, when you come to dismantle the exhaust threads and washers, it still sticks exceptionally well. It's a ketoxime based curing silicone and the MSDS might frighten those of a milder disposition, so take care with it. It doesn't seem to last in the tube for as long as the acetoxy curing types either, but it's still worth the money.

For those in the UK, it is easy to find, as surprisingly for such a specialist item, it is available from Halfords.

Submitted by keith_brown on Fri, 27/07/2012

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Thanks for all comments, I think I may start with the Hylomar and see how it goes. Dave it seems to be still readily available with lots of references on amazon for it. Point taken about the silicone on exhaust nuts, just using standard bathroom silicone prob not the way to go, Chris the loctite product looks fairly good however. John I have some copper ease grease that is rated up to 1150 degrees c, i got it from halfords, i think to use for general nut and bolt assemblies, I presume if this is used on exhaust nuts you would have to tab washer them to stop them coming loose.

Submitted by robert_vaughan on Sun, 29/07/2012

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Previously wrote:

Thanks for all comments, I think I may start with the Hylomar and see how it goes. Dave it seems to be still readily available with lots of references on amazon for it. Point taken about the silicone on exhaust nuts, just using standard bathroom silicone prob not the way to go, Chris the loctite product looks fairly good however. John I have some copper ease grease that is rated up to 1150 degrees c, i got it from halfords, i think to use for general nut and bolt assemblies, I presume if this is used on exhaust nuts you would have to tab washer them to stop them coming loose.

No, if you use copper ease grease on the exhaust nuts you will be able to tighten them correctly (read very tight) when hot!!! & they will not undoo themselves. I have not had a loose exhaust nut in over 35 years by following this method.

Regards

Bob.

Submitted by keith_brown on Sun, 29/07/2012

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Thanks for clarification Bob, I have all new bits for the exhaust and the nuts look pretty meaty. Are we talking I need one of the special c spanners I've seen in pictures, or a sharp tap with a block of wood and a hefty mallet? (when hot of course)

Submitted by david_henshaw on Mon, 30/07/2012

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Previously wrote:

I have my 71 Norton engine back in the frame and am about to start replacing covers. Most of these have waxed paper gaskets; when rebuilding car engines I used to smear these with Hematite red or hylomar blue gasket sealant. Anyone any thoughts on this? Or suggestions as to what may be a better product to use. Maybe just assemble them dry?

Hi Keith,

I have some heat & Fuel Resistant Gasket on my website www.tankcareproducts.co.uk I use it in my workshop, as all the products on there. Its made by a british company, Delta adhesives who have some great products.

Ian Potter

Attachments delta_pic36a.jpg

Submitted by keith_brown on Mon, 30/07/2012

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Seems like I'm being chastised for hammering my nuts with a bit of wood and a mallet, but don't despair I have found my 18" Stillson.

As I plan on keeping this beast for the foreseeable future, I will probably invest in a spanner, they seem cheap enough and I can hit that with my mallet.

Thanks for info Ian, although I have already bought and started with the Hylomar. The tank products may be of interest however when I start sorting that.

Submitted by dave_graham1 on Wed, 01/08/2012

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You don't need to hit it with a hammer, just pull it up tight with your hand. You can feel how tight it is then :)

 


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