Ray Winkowski

Hi I have had the same issue on my 1999 Suburban C1500 with a new crate motor after 25000 miles. I checked and changed everything that could possibly cause the problem with no luck. I discovered the intake manifold gasket originally are paper. I took intake off and found the gasket was leaking coolant. After changing to metal gasket I finally don’t have the problem. I just moved from California to Oregon with our Suburban fully loaded without an issue. 2 months later and the coolant level maintains. Good luck