[nascarnelson]

i have 68 gto 400 t 400 45,000 actual. i am getting ready to replace the water pump. just wondering how tough a job it is? i am getting older now but i like to work on my car when i can. it runs at 180 degrees while moveing but when at a stop light or while driveing in a cruise you can watch the temp go up while setting there. new 4 core rad and hoses. thanks for any advice you can offer. you guys are the best

[David Jones]

What kind of fan/fan clutch arrangement do you have? It's possible that your fan clutch has died instead of your water pump.

[Sirrotica]

Have the engine up to operating temperature, get a piece of cardboard and wrap it into a tube and see if at idle you can stop the fan with the rolled up cardboard (Please be careful of your hands). If you can the clutch is bad and most likely causing overheating.

Waterpumps usually go bad and start leaking or the bearing goes bad. There is a thread that tells about the best types of impellers and how to optimize the distance of the plate behind it to get the ultimate efficiency which many times cures overheating problems. The replacement of a waterpump is fairly easy and can be accomplished with basic tools and knowledge.

I would read this thread: http://forums.maxperformanceinc.com/...d.php?t=411256
to find out the idiosyncrasies of the Pontiac waterpumps and how to optimize them for best cooling. Hopefully this will get your Pontiac cooled down while teaching you some basics about how the pump functions best, good luck.

[dave21042]

You can go to you tube and watch a video on the how to modify the water pump.
http://www.youtube.com/watch?v=UdyAo5546JQ

[north]

I would agree that it sounds like a fan clutch that isn't clutching anymore.