You learn something new every day

In gathering all the pieces I needed for the clutch replacement, I learned something new. The procedure will require the removal of the transfer case cover. The cover is bolted on to the transfer case without a gasket. Several folks on F-Chat have suggested using something called Loctite 518 as a sealant. What is Loctite 518 and what's so special about it? It is an "Anaerobic Gasket Eliminator." Anaerobic? What the heck is that? How's it different than the good old Permatex RTV Blue?



As the name would imply, an anaerobic gasket sealant works in the absence of air. When used between metal mating surfaces, the thin film is not exposed to air and therefore cures. Any excess which squishes out the side are exposed to air, and therefore will not cure. Regular RTV sealant, on the other hand, will cure no matter where it is. What's so important about this?

Let's say you're putting on a valve cover and you use a bead of RTV to seal the gasket surface. Some of it squishes out and cures on the inside of the cover. Let's say that some of this "extra" on the inside breaks loose and wanders through the oil passages of the engine. If the errant RTV blob is big enough, it could plug a passage and starve your engine of oil.

Supposedly, an anaerobic sealant will not do this. Any errant sealant on the inside surface will not cure because it's still exposed to air. If it does break away, it stays a semi-liquid blob and will not potentially plug an oil passage. That's the theory anyway. It sounds good to me so that's what I'm going with. It seems that no one at the local auto parts stores has even heard of Loctite 518. They all stock Permatex products. Permatex does make an anaerobic sealant, but since the Loctite product was so highly touted, I wanted to track some down. Since I still had some time before the teardown, I just ordered some from Summit Racing.