1999 Pontiac Grand Am 3.4L V6 cooling system issues

Maintenance/Repairs
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1

I am working on my daughters 1999 Grand Am with the 3.4 L V6. I was told by a shop that the heads gasket(s) were blown and needed to be replaced. So, because I’m her dad (a better than average backyard mechanic) and she’s a college student with more debt than money, I thought I would tackle this to save her some money. Well, the front head, cylinders 2,4,6 showed a “clean” cylinder2 while 4 & 6 looked ok. The rear head had no visible signs of leaking to a cylinder. After cleaning and reassembly, everything appears to be in order except for;

  1. When starting from cold, the engine runs for about 15-30 sec. and the radiator fans come on. I thought that this was strange since this didn’t happen before and I was told by someone that the fans don’t come on until the coolant temp reaches 230 degrees.

  2. After running the vehicle for about 20 minutes the heat to the interior is very good. In fact its downright HOT. However, the temp gauge on the dash reads “100”. Thinking I broke the sensor while I was working on it, I replaced the sensor. No change.

  3. The “Low Coolant” light on the dash is on, yet the level in the surge tank is above the full cold mark. I’ve replaced this sensor twice. No chage.

I would appreciate any advise here. Thanks for your time.

2

This is one of the engines that had issues with the intake manifold gasket and Dexcool. Do a search on “3.4L Dexcool” for more info. There was a class action suit, but the time limit has passed for any reimbursement.

My 2000 Blazer had the intake manifold gasket replaced in Feb 04. The coolant level was dropping slowly (~1pint/month) any my mechanic found a few drops of coolant in the oil after it was drained.

In addition, if the coolant is sludgy, change the radiator cap. Dexcool will sludge up if air is getting into the cooling system.

Ed B.

3

Sounds as if you have air trapped in the system and it needs bleeding.

4

@edb1961 you are right about the intake gasket issues on the 3.1 and 3.4

And I would have suggested that the intake gaskets, NOT the headgaskets, were the problem.

But it’s too late. And in any case, the intake gaskets get replaced when doing a headgasket job.