[Anonymous]

bought a 2006 Pontiac Grand Prix gt 3.8 v6 supercharge last week, 50,000 miles. Now I heard, many gm cars, have plastic intake manifold gasket, that melts after awhile and causes antifreeze leaks.Does anyone know if the 2006 Grand Prix were made with plastic or metal intake manifolds gaskets. I read somewhere that 2006 Grand Prix have metal? I’m not sure? thank you.

[Kristin Bentley]

I have a 2002 Pontiac grand prix. I just bought it, it made it 3 miles overheated. I had it towed home. We have replaced the thermostat, egr valve, water pump, flushed the radiator, flushed the heater core, added head gasket fix from BARS, added stop leak for radiator and heater core. Did oil change due to mixed coolant and oil. Started car no real issue, added coolant, dry thick white smoke is coming from engine and tail pipe, no heat still. Seems coolant is clean, oil is clean. smoke coming from back of engine by heater core entrance into firewall or exit from fire wall, unable to determine. Spark plugs look new, engine runs same when distributor caps removed one at a time.

[Anonymous]

White smoke from tailpipe means the engine is burning coolant. Possible blown headgasket, or the upper intake manifold plenum has cracked. We have seen this a lot. If the upper intake (plastic) is removed, you may see coolant in the lower intake manifold. This means the plenum is cracked.

[Anonymous]

i have replaced everything i can think of on this thing and still overheats on me i don’t know what else to do any help

[Protech]

There could be many different things causing an overheat condition on your vehicle. It could be something as easy as a bad thermostat, such as being stuck open or closed. Or it could be as extreme as blown cylinder head gaskets or a cracked cylinder head or block. The first thing to do would be to check for any leaks, such as from the water pump, intake, cylinder heads, hoses, etc. If there are no leaks, then you are losing coolant internally which would indicate a bad head gasket or cracked head or block. If you see a constant stream of bubbles in the coolant while the engine is running, you are getting compression pumped into the cooling system, which is another symptom of a bad head gasket. You can try a cylinder leak down test with the proper tools, and there is a tool you can use to pressurize the cooling system to help find leaks too.

[Protech]

The problem you are referring to has been fixed several years before your 2006 Pontiac was built. You do not have to worry about this problem. Yes, the older ones had a gasket problem as well as the upper manifold itself. The manifold would burn through since the EGR valve passage was too close to a COOLANT passage, and the plactic manifold was too weak to handle it. So the manifold would burn through, cause an internal coolant leak, and sometimes even lock up the engine- this is called “Hydrolock”. The engine would not turn over because of all the antifreeze in the cylinders. Once the spark plugs were removed, cylinders drained, and manifold replaced- the engine would run normally with usually no ill effects.

[Author]

Posts