The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.Google+
Car Problem Reports
Chevrolet Express 1500 Intake Manifold Gaskets May Leak Coolant or Engine Oil
Chevrolet Express 1500 Problem
Engines Affected: 5.0L V8, 5.7L V8, Gasoline
Average Mileage: 99,642 mi (50,000 mi - 145,000 mi)
Visitor, 2000 Chevrolet Express 1500, 5.7L V8, 75,000 mi
Upper intake manifold gasket leaks. I had a cracked radiator which I replaced but the leak moved to the back of the engine block. Found out that the gaskets are made of plastic and possible corrode due to the antifreeze chemicals. It is a huge job to replace. My mechanic suggested trying the radiator sealing tabs first to see if it would fix the problem. It did. I talked to another buddy of mine who is a service technician and he believed that even brand new, they put those tabs in... faulty design!!!
Visitor, 2002 Chevrolet Express 1500, 5.0L V8, 68,000 mi
Noticed a smell of Antifreeze and thought the lower radiator hose was bad. Took it into the repair shop and after some searching they found the Gasket to the INtake Manifold was leaking. With this many reports, there should be a recall.
Visitor, 1996 Chevrolet Express 1500, 93,000 mi
Mechanic noticed oil and antifreeze leakage. Replaced lower intake gasket.
Visitor, 1999 Chevrolet Express 1500, 5.7L V8, 50,000 mi
Had a substantial antifreeze leak (about a quart on the floor) attributed to a ruptured intake manifold gasket. Mechanic said that these failures were not uncommon but that they usually occurred around 100K miles. Installed a steel gasket with an insert. No further problems since 2005.
Visitor, 2000 Chevrolet Express 1500
Same problem recall GM
Visitor, 2002 Chevrolet Express 1500, 5.0L V8, 87,000 mi
Leaking very slowly, thought it was a leaking water pump but turned out to be intake manifold gasket, was quoted around $1000 to repair with 7 hr labor. Not sure if I am going to do it yet.
Visitor, 2001 Chevrolet Express 1500, 5.7L V8, 80,000 mi
manifold gaskets leaking coolant.
Visitor, 2002 Chevrolet Express 1500, 5.7L V8, 120,000 mi
Loosing antifreeze, engine overheating. Poured gasket sealant in radiator to solve the problem. I don't think in really worked well
Visitor, 1999 Chevrolet Express 1500, 5.7L V8, 145,000 mi
Oil pressure dropped and discovered coolant was in oil. Not sure if damage was caused to the engine, so repairs have not been done.
Visitor, 2000 Chevrolet Express 1500, 5.7L V8, 120,000 mi
Gasket leak had come back after replacing the spider assembly. Threw in the coolant tabs again and everything seemed fine but then went for a long road trip (+1000 miles) and, fortunately, when I got home it came back with a vengeance! It is a heck of a job... should have done it when I did the spider assembly.