To All:
In a recent post to this Group regarding assembly of a VW engine, I said the only place to use an RTV compound would be on the base of the cylinders where they contact the crankcase.
This caused me to receive a number of messages asking about using RTV on the TINWARE.
Apples vs what-ever. The first message was about assembling the ENGINE and while the Tinware may be considered a part of the engine if it's going into a bug or bus, that isn't true if the engine is going into an airplane.
But YES... Do use RTV to seal any SMALL gaps in your tin-ware. I use the black stuff.
Don't worry about the temperature. High Temp RTV means HIGH temperatures, as for mufflers and the like. Your engine should never see any temp over 450 degrees or thereabouts and temperatures are not considered to be High until you're up around 500 degrees on the Fahrenheit scale.
If your tin-ware is DAMAGED or has been gnawed upon for the installation of an air conditioner or what-have-you, you should consider hammering everything back into shape then WELDING on patch panels. But if you don't weld you can try cutting up beer cans, grinding the paint off of the tin-ware where the patch is to go, then attaching the patch with JB Weld or RTV. The tricky bit here is holding things in place whilst the adhesive cures. Pop rivets work very well for this, assuming you know how to use them. (You need some #6 sheet metal screws to hold things in position while getting the rivet into the hole.)
So.... do I use RTV on VW engines? Dambetcha, cowboy. But not any place where it might get INSIDE of the engine. I slather it on the Tin-ware, wherever I think it will help keep the cooling air from leaking out.
-Bob Hoover