I was not able to find anything on this with a search, so let me start a new post on it.



For anyone that has assembled an engine what have you used on the inner coolant seals? Hylomar or petroleum jelly?



On all of the engines I have assembled I have always used Hylomar. As I am getting ready to assemble my next engine I was wondering if I ought to try just using the petroleum jelly. Every engine failure that the engines I've assembled has suffered has been from a coolant seal going away. Granted - it has never been a quick failure nor could I claim that the cooling system or boost was not to blame but I just would like to hear some opinions on the subject.



Jason

 

All it does is hold the seals in place during assembly so it doesn't really matter.. and I think that coolant seal failure is usually due to overheating.. but I may be wrong..

 

i use vaseline, it works great. you just need enough to hold the seal in



mike

 

PJ is only to hold the seals in place during assembly, it is not going to contribute to sealing the way hylomar will.



J

 

Hylomar is used in the groves for the coolant seals. I have only heard of vaseline being used to hold the side seals in place. My understanding is that you want the coolant seals firm in the grove.....Vaseline will not keep them there. But then again if the housings are good and flat they should put ample pressure to hold the seals there.

 

vaseline does a great job of holding the water seals in



mike

 

So mike do you not use hylomar for the coolant seals then?



J

 

UH, Vaseline is good for lots of stuff..

 

I thought this might cause some debate. The Mazda factory manual says to use petroleum jelly on the water seals and doesn't mention Hylomar.



Since Hylomar never hardens I was wondering if it actually contributes to the sealing any once the engine has been heat cycled. I wondered if it might actually make the seals slide around in the grooves since it doesn't harden...



Also - has anyone ever heard of O-ringing the housings much like on a high compression piston engine? I would think a very small, rounded groove milled into both the rotor and side housings and then O-ringed with a copper wire would make a great barrier against heat getting to the actual coolant seal.



Jason

 

Hm, maybe . . . but there's very little room to put an o-ring, probably no more than 4mm, just going by memory. How big an o-ring would you propose?



J