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Greg A
Greg A, Master Troubleshooter
Category: Pontiac
Satisfied Customers: 7953
Experience:  Working with Electronics & Cars for 25+ Years
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2001 Pontiac Montana: engine temperature..cruising..highway speeds

Customer Question

I have a 2001 Pontiac Montana. I'm having issues with engine temperature and I suspect it is just in need of a thermostat but want to be sure. If we are cruising at highway speeds the temperature is in the normal range. If we are at street speeds, the temperature approaches red line.
Submitted: 7 years ago.
Category: Pontiac
Expert:  Greg A replied 7 years ago.

Hello & Welcome,


Can you tell me what the "normal range" is on the gauge?


Have you checked to see if the radiator cooling fans are working?



Customer: replied 7 years ago.
actually I don't know the exact temperature but the midline on the guage. If you need the exact temp I can look when my daughter gets home and get back to you. No where are the cooling fans?
Expert:  Greg A replied 7 years ago.

Hi again,


Middle of the gauge sounds about right for normal operation. I don't suspect that you have a thermostat problem because that is where the gauge should be.


The cooling fans are mounted behind the radiator. There is a possibility that they are not coming on at the right time because of either a fan problem or a relay problem.


Here is a site that talks about the cooling system fans on a similar GM van (identical really). It gives details including schematics of the system along with relays and fuses involved. I would check that system to make sure everything is working properly.


One other thing you can try is to turn on the AC system and see if the temperature comes down after a couple of minutes. This is assuming that the AC system is working properly because switching on the AC will also cause the fans to run.


I would also check that the cooling system is absolutely full, when the engine is cool. This should be checked at the radiator cap and the coolant should be right up to the very top. Also, the overflow bottle should be about half full at all times, or at least between Full Cold and Full Hot marks on the bottle.


I hope this helps. Please let me know what you find or if you need more information.


Take Care, Greg A.

Customer: replied 7 years ago.
OK I'll check the fans, I know the AC isn't working (its blowing hot air and I just assumed it was because I needed to have the freon recharged). However my concern is when we are driving at city speeds - about 40 mph - The guage is actually hovering one tick or so below red line.
Expert:  Greg A replied 7 years ago.

Hi again,


For the AC not working, it could be because the cooling fans are not working, but then the AC would work at highway speeds. There could also be a freon leak. The condensers on these particular years (mounted in front of the radiator) were prone to a leak developing at the lower passenger side of the mount. There was a bulletin out to use a different style mount so that wouldn't happen.


But I would definitely recommend checking that cooling fan system. The fans have the job of keeping air moving through the radiator at lower speeds, and if they are not working, it could cause this problem.


Thanks, XXXXX

Customer: replied 7 years ago.
Thanks. I'll take a look. The AC doesn't work regardless of speed. so must be the leak you mentioned.
Expert:  Greg A replied 7 years ago.

If you have had the freon leak out, it is a good possibility that the condenser had/has that problem. Here is another picture of a leaking condenser in the spot I mentioned.


Please let me know what you find related to the fans.


Take Care, Greg A.

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