Quote:
Originally Posted by RustyWiring
Hello everyone.
I've been lurking on this incredible resource for a few months - since I purchased a 31 AA stakebed in April. I rebuilt the engine over the summer and am breaking it in now. So far, so good. 70 miles, 5-10 at a time, and only had to be towed home once early on! (my smoking distributor cried 'oil me, jerk!' but not before the points lobe melted away.)
Anyway, having little A experience, I thought to turn to the experts here with this issue: Motor is not hot but when I get the RPMs up, water blows out the radiator cap. I drop the RPMs, no blow over.
My cap seems loose to me; even for a non-pressurized system. There is a ratty, red gum seal in there but it makes little-to-no contact with the cap when rotated tight. At times, the cap even rotates a small amount (~10 degrees) while driving.
Is that sort of aggressive water flow normal?
Does the closed radiator cap need to be snug/sealed?
Should I get a new cap?
{Thanks to all of you for your generous insights on this board. I was able to anticipate several issues during rebuild because of reading the 'barn. For instance, when the engine didn't want to fit back in, instead of cursing, I remembered reading here that that happens and to spread the frame. Used a bottle jack and 4x4 and in she slipped.}
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Sounds like the classic leaking head gasket. As long as the engine is doing light work it is happy. As soon as the engine is working harder the cylinder pressure increases and the hot gasses bypass the head gasket and boil the radiator. Forget looking for water in the oil, the hot gas only exits through the water jacket when the pressure rises. Try retorquing the head. Also as mentioned seal the radiator cap and adjust the water level. Rainmaker Ron