Niel,
I am like you, I have used red RTV on head gaskets for years, the trick is the coating of the RTV must be very thin, I usually run a very small line of the stuff around things that I think need to be sealed, i.e. water and oil passages, and then use my fingers to "rub" the RTV down to a very thin coating. Let is set for a few minutes and then assemble. With head gaskets we are only trying to fill the very small possible irregularities between two machined surfaces so the coating, copper plate or red RTV needs to be thin. To many people just gubber on a big bead of RTV and then when at assembly it comes out the sides, down the water and oil passages and causes havoc. In this case the less you put on the better.
At Interscope we had many problems with exhaust header gaskets blowing out, both NA and turbo engines, we finally went to using just the high temp red RTV and never had a problem again. We did surface grind the header flanges so they were flat and true.
Rex
Neil and Rex, et all,
A couple of thoughts about these 2 subjects based on my long experience engineering racing engines:
Using RTV on head gaskets should resolve some "finicky" sealing issues, if the head gasket is "uncoated" or has a coating that is compatible with RTV. I also have used the "thin schmear" method, with success. But there are some gasket coatings that are not compatible with silicone based products. Check with the gasket mfg's tech department if it does not seem to work. It is definitely required to allow adequate time for the RTV to set up, before exposing it to water, oil, or pressure. You simply need to allow adequate time for the stuff to "glue/bond" the parts together. Because uncured silicone sealer is one of the best lubricants on the planet . . . . .
I also have used "red" RTV as a substitute for header gaskets. The stuff was invented to bond ceramic heat shield "tiles" to the Space Shuttle, so it is VERY heat resistant. Since the heat of the exhaust "cures" the stuff quickly, as long as the mating surfaces are flat, as Rex noted, it can be put into service in short order. Again, if the surfaces are "wavy", best to let it cure before exposing it to heat and pressure. For turbo exhaust systems that run very hot in service, a couple of applications have needed to have "beaded", MLS, stainless steel gaskets installed between components. These have been 4 cylinder applications with lots of vibration. Go figure . . . .
Also, once the red stuff has cured on your clothes, it's there forever . . . . . The fibers of the clothing will fail before that stuff will come off. Trust me on this.
Slimedboy
