white smoke...

[davidimurray]

I'm using a Stant pressure cap which is 20-25lbs. It does not sound to me like a pressure a radiator can't take, but perhaps the problem come from there too.

I thought that 14psi was about normal? 14psi gives a boiling point of 119c whearas 20psi gives a boiling temp of 125c

[voucht]

Yes, Adrian is right! I wake up every morning of my life next to the reason I'm now living in Sweden, and I'm the happiest of men

But we don't plan to stay in Sweden forever, and might move back to France or another warmer country within one or two years. And if I can get the Roadster registered there, it will be so good to drive it in the southern France weather!

Well, I drove 600km in the day yesterday, and came back with a pair of nice Cobra seats. Unfortunately, we could not take the DOHC out of his Sierra, so no engine so far... I think I'm going to buy the one I saw at the scrap yard, but will do that only after the inspection, next month.

Originally Posted by davidimurray

I thought that 14psi was about normal? 14psi gives a boiling point of 119c whearas 20psi gives a boiling temp of 125c

Yes, I have been stupid enough to use one of these high pressure radiator caps we use on racing cars. It was the only one available when I ordered my parts from France last year, and I should have waited. The purpose of these high pressure caps is too keep the cooling system under a higher pressure, because the higher the pressure is, the better the calories exchange is. But the whole circuit has to be planed for this pressure, and it was certainly too high for my system/engine/radiator. Perhaps the head gasket broke just because of this actually, and I think you should have a reinforced head gasket when you use this kind of high pressure radiator caps.

So, I will definitely go back to a lower pressure cap, same pressure as the one originally used with the Sierra DOHC.

Thanks.

[flyerncle]

You have just been unlucky Sylvain,colling system will stand much more pressure than the cap say's or they would be bursting more regular if they got slightly over the rating of the cap.

I have noticed cap pressure's have risen and a lot of cars do have high pressure systems and as you rightly say the heat transfer is better and the boil point raised.I suspect its all to do with emissions and better combustion.