2001 Pontiac Montana 3.4l Overheating Problems

[RobGuro]

Hello all, just wanted to get some information and was tired of Googling other AF posts that were not specific to the problems I'm having, so I thought I'd post one myself.

I have a 2001 Pontiac Montana with a 3.4l engine. It has been having problems overheating, which I've come to find out is incredibly common with these vehicles. It started overheating a few days ago, but we were able to limp it home via just adding water and giving it time to cool down. I'd say I was able to make it about 10 miles at 35 mph before it overheated. When I checked under the hood, I saw a tee connection at the back of the engine had burst, the plastic had decayed and was incredibly brittle. I cleaned out the hoses and replaced the tee line in addition to bleeding the cooling system, but I am still having overheating problems. No leaks anymore that I can tell, but now water is forcing itself into the overflow reservoir from the radiator and appears to be boiling there - the water is bubbling violently. The most common cause for this that I am hearing is the head gasket, but I was wondering if there were some other problem areas I could check before I bite the bullet on a $1500 repair.

Thanks!

[Tech II]

If you repaired the leak, filled it up with the proper mixture of coolant, and correctly burped the system of all air, then It's a good chance that you have a head gasket problem....depending on how much coolant you lost and how far you drove it, it could have damaged a gasket or warped a head....you said it had been overheating, but you continued to drive it, so that is a problem right there....

You can verify it this way.....make sure your system is full.......run the vehicle to normal operating temp......when you see the temp start to go past the midway point, and bubbles show up in the reservoir, shut down the car overnight......

The next day, remove all spark plugs......there are two harness on the driver's side of the ICM(ignition control module that is underneath the 3 coils), and one harness on the passenger side of the ECM......disconnect the harness on the passenger side....this removes power and ground so the coils will not fire.....remove the injector fuse or just disconnect the injector harness so the injectors don't fire......now look underneath the hood, especially where #1 cylinder is(passenger side, rear bank)......have someone crank over the engine....if coolant comes out of any of the cylinder holes, that is usually a head gasket problem.......more often than not it will be cylinder 1.....

[mjdemaris]

I have a 2000 Montana, 3.4L, and have had the intake manifold gasket and two head gaskets replaced in the last several years. Now, I am getting oil leaking into the coolant, again. Same as had happened before.

We also have had frequent overheating problems. I agree, this is not a good engine to own.

[Andywev]

Change the thermostat.