2002 Pontiac Grand Prix with 3.8L Series II SFI OHV V6
Well known issue with these. The Upper Intake Manifold Gasket melts in close proximity to the EGR stove pipe allowing coolant and oil to get in bad places. My upper was leaking, but the Lower Intake Manifold Gaskets were a mess!
For about a month, it was eating antifreeze. I kept topping it off, until the inevitable, it overheated. Water started pouring from broken Upper and Lower Heater Bypass Pipes (Identify this leak) (Fix this leak) and oil mixed with the antifreeze through the intake gaskets. For the first time, it was now running rough. Feared the worst.
After a good compression check, I replaced all the gaskets from the lower intake manifold on up, the water pump, plugs and wires. Fired right up! All good! AHOO!
Redesigned Lower Intake Gasket Set from GM 89017816 ($65 dealer)
Improved Design Upper Intake Manifold and Gaskets from Dorman 615-180 ($130 autozone)
Dorman Heater Pipes 47065 ($5 autozone)
Heater Adapter O-Rings 24502375 ($10 dealer)
Disconnect the wire harness from the ICM before running a compression check!
To replace the water pump, you must remove the power steering pump. Not the PS pulley! (Video)
Do not use Carburator Cleaner on the throttle body and Emission Sensors! They make special cleaners for throttle body and MAF Sensor.
Wish I had used a little Permatex on the Heater Pipe O-Rings. They weep a little.
The upper and lower gaskets go on without dressing! Just a dab of Gasket maker in the corners of the lower (above and below).
The UIM comes with a new vacuum port and o-ring, but it felt loose to me. I added the old o-ring to the upper shoulder to snug it up to the manifold.
Step by Step help at www.AllDataDIY.com
Very happy with this fix. About 75 people read this post every day. Give me some feed back! Did I help?