Maybe a stupid gasket question, but...

[trbig]

Why can't a person just use clear 100% silicone sealant as a gasket material? Temps wouldn't be a problem and it's used to seal everything else.. although the everything else tends to be stationary. It's gas/alcohol/oil impervious.. so was just wondering. It's a heck of a lot cheaper than the other stuff.

[crazy steve]

I've used tubes and tubes of the clear stuff when I was working, but like you said, mostly stuff that didn't move/vibrate or see big temp swings. I have used it in a pinch more than once for car/bike applications, but it seems to shrink some over time and lose it's 'bond' to the surface, and definitely loses some of it's elasticity.

I've gone to Yamabond for pretty much any sealing I do anymore, unless it's a non-machined or uneven joint where you need to 'fill'; Yamabond is too runny for those. It 'flows' better IMO, and never leaves a 'bead' squeezed out that can fall off and go someplace inconvenient. Yeah, it's expensive and the damn tube goes bad six months after you open it if you don't use it, but what the h....

[Bikes]

I was a foreign auto tech for twenty five plus years.....rebuilt a million (not really) vw beetle motors....other mechanics would use silicone, brown permatex, silk thread, all kinds of tricks to keep the cases from leaking.......an old Texan, retired Navy flight engineer told me to use rector seal number 5......any hardware store has it in the plumbing section. That was a loooong time ago, i still use it....NEVER had a case leak or anything else I used it on. I also have rebuilt a bunch of Harley's.....always used it, never leaks.....comes apart well and cleans up easy when you have to.....no foolin....
Rector Seal No. 5......
I've already used it on my XS.....

[Bikes]

That being said, some parts, covers etc. are clearanced to use a gasket....and you should. Dont want anything rubbing or grinding away in there....

Also, Steve says the yamabond goes bad after a while, same for most rtv type sealers....not Rector Seal, I have a can thats probly ten years old, still goooey good......

[natemoen]

Silicone is actually corrosive to steel, and possibly other metals that I just don't know of off the top of my head.

[MPittma100]

Sealant

Silicone is actually corrosive to steel, and possibly other metals that I just don't know of off the top of my head.

Permatex Ultra Grey is non-corrosive. Can be used in electronic environments. It is quite strong when cured. I have used it for years mostly on engine applications. Works for me.

[BA80]

I have used all kinds in all kinds of applications. As a rule, any of them work fine and will outlast whatever you are fixing. I've even used it for header gaskets on race cars and it worked fine.

Ultra whatever color will stick even in an oily environment so I do prefer the ultra. Fixed holes in oil pans with ultra blue and cardboard during dirt track races before and it didn't leak a bit.

My $.002

[trbig]

I have a preferred sealant already.. Wasn't asking that. I was just asking about 100% silicone. I had no idea it was corrosive to some metals though.. never heard that before. I was just wondering since I don't have to make a trip to the bike shop for it, and being clear, you don't have to worry about it squeezing out and looking bad.

@ Bikes.. Many people on here have no gaskets on their bikes. (Not counting head gasket) Valve cover, side covers, clutch cover, oil pan... all done away with the gasket and just use sealant. Nothing will rub and nothing will grind.

[natemoen]

Permatex Ultra Grey is non-corrosive. Can be used in electronic environments. It is quite strong when cured. I have used it for years mostly on engine applications. Works for me.

As Tod said, we are not talking about specific sealants and gasket makers here. We are only talking about 100% silicon.

[MPittma100]

SILICONE Sealant

As Tod said, we are not talking about specific sealants and gasket makers here. We are only talking about 100% silicon.

If 100% SILICONE is corrosive, why would anyone use it? I would recommend not using it on anything automotive. Buy the gasket.

[natemoen]

If 100% SILICONE is corrosive, why would anyone use it? I would recommend not using it on anything automotive. Buy the gasket.

It is all a matter of what it is used on. When used on. Read the tube of 100% silicone caulk it specifically states not to use it on steel. It causes a chemical reaction and corrode s the metal.

[TomB]

I've even used it for header gaskets on race cars and it worked fine.

+1, I use it on the drag bike turbo and headers, crank cases halves and outer covers.

It can be slightly corrosive as it has Acetic Acid in it (that vinegar smell) but having used it for the last 35 years on m/bikes and cars have never had a problem, I have been told it attacks aluminium cases but have never seen that on old British bikes and Japanese bikes.

Apart from head and base gaskets all my XS1100 covers use no gaskets, clear silicon sealant instead.

[jetmechmarty]

I had to investigate further.

RectorSeal® No. 5® pipe thread sealant is a soft-set, slow drying compound which seals, lubricates, and protects threaded pipe and fittings. It can be pressurized immediately for piping up through 2″ and 100 psi(for natural gas, air and water only) and is ideal for application with a wide variety of fluids and gases, including potable water applications. Recommended for use on threaded galvanized steel, iron, brass, copper, aluminum, stainless steel, polyethylene, fiberglass reinforced and PVC pipe.

Not recommended for use with ABS,CPVC pipe or oxygen, chlorine and other oxidizers

[BA80]

If 100% SILICONE is corrosive, why would anyone use it? I would recommend not using it on anything automotive. Buy the gasket.

I'm not saying use the 100% silicone but there are really good sealants out there that didn't exist when these bikes were built. Most of the aluminum to aluminum seals on automotive engines today are just silicone. Oil pans, timing covers, ect., ect. Gaskets are only used in hard to seal places.