This seems to be an inherit problem with these cars......I have had my 2000 MC 3.4L for two years now and it has always run hot. I tried new water pump, Hoses, Flushes, Thermostat......everything but a radiator, new engine or new gaskets. Finally I tried a Fan Switch from Casper Electronics from PFYC.com . I was not impressed with the installation instructions, but MY OH MY.... does it keep my engine COOL. It also lets me control when i need the fans. This device saved me from getting a new engine or at least chasing my damn tail forever. It works better than expected, now how many things do you pay for nowadays that you can say that about. I will help anybody who installs this Product in there car to the best of my ability. If you do have other problems.....it wont help those....be sure that all the other cooling system components are working correctly.

 

All you did was put a bandaid on a leaking artery...congrats.
If you engine is overheating, having a pro diagnose the problem and repair it will likely save the engine. Putting a fan override switch to over cool an engine will only make it worse in the long run.

At least when that 3.4 grenades itself you can think about swapping in a 3.8

 

Whenever it overheats can you bleed the system?

You might have a headgasket problem allowing air in constantly now matter what you do.

 

You are both right.......its a band aid....and.....its probably the Gasket, I have had it looked at several times by so called competent mechanics and I got several different answers. However there are bubbles showing from the radiator cap, so I believe that the head gasket is bad. But, its been running that way for two years, you would think that it would get progressively worse, but not so. When it goes, its Jasper crate engine time. I do believe too that the cooler the engine runs now, the longer it will last, saving me money for now.

 

The 3100 and 3400 engines are notorious for intake gaskets going bad and some head gasket failures.
I've done a lot with the 3100's (worked on about 4-5 of them between friends and family, and I am still driving the last of the 3100s I've wrenched on a '94 Grand Am with 210K on it).

Noting that you have bubbles in the coolant is a strong sign of a head gasket. My Grand Am blew a head gasket and took me forever to determine that (I actually had to turn it over to a good friend of mine who is a GM mechanic, and he confirmed it, I did the wrench work and now the car runs great).

The Grand Am was developing constant air pockets and the cooling system was over pressurized (it actually blew the gasket out of the side tank on the radiator, lucky for me the radiator had a lifetime warranty, easy change when the heads were off).

If you have over 100K on a 3400, then intake and/or head gaskets are a serious consideration (not saying they are the definate cause, but something worth exploring). If the head gaskets are failing, you may not really be running hot, it's just an air pocket getting into the system (but as I mentioned, that can cause other problems if left unrepaired).

Proper service to the 3100/3400 and that engine will serve VERY well (I am so convinced of that, my wife and I bought an '05 Impala with a 3400 and 150K for a steel in December).