C3 Cooling System Leakdown

[Herbert L.]

I was a little suspicious of my not-so-recently rebuilt 69 L36 engine when I first started it before the body drop. It appeared as though it puffed a little steam out the rocker cover vent hole. I drained the oil and it looked OK. Then I pressurized the cooling system to 17 psi and waited. After 24 hrs it dropped to 10 psi with no indication as to where the air was going. I bumped it back to 15 psi and after 18 hrs it was down to 13 psi.

Does this sound acceptable? Should I tear into it? Should I add some form of stop-leak, or do nothing?

Thanks

[Joe L.]

Re: C3 Cooling System Leakdown

Herb------

GM recommends the use of coolant system sealing pellets with every coolant refill. They've had this recommendation for quite a few years now. So, I'd go ahead and install the pellets and see if that improves things. GM #3634621. Your local GM dealer should have them.