[maxwedge]

Originally Posted by animekenji

Common defect in the Series II 3800. They mounted the hot EGR valve on a piece of plastic not designed for extended periods of extreme heat. It usually starts as a slow coolant leak but can end up with large volumes of coolant being dumped into the engine. This can really suck if you're tooling down the highway and get a hydrolock. Internal engine parts can break and if the coolant gets down into the oil pan, it's all over. The highly polished and finely fitted crank and bearings will corrode and eventually sieze, even if you change out the contaminated oil and replace it with fresh. You are catching the problem early, so find out what you need to know to replace the intake before this gets worse. I am not certain if the GM part from the dealership has been redesigned or not. I know a company called Dorman makes a part without the coolant passage, but I think you need to replace the lower intake as well (that coolant has to be re-routed someplace, right?). The series III engines use an aluminum upper intake, so GM has acknowledged the problem, in their own way, even though they won't fix it under warranty, like they should.

Actually Dorman's manifold is reinforced in the problem area, not eliminated.