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overheating problem


mmgp3100
10-25-2010, 01:45 PM
Hello, I JUST bought a 2001 Grand Prix 3100 v6. When i looked at it the temp gauge was not reading anything. I figured it was just the sensor. The next day i was under the hood to replace it and noticed that it was unplugged. I plugged it in, started it, and it started to head for the overheat temp. This was a lapse time of about 1.5 minutes. I checked the Tstat to see if that needed replaced. There was no Tstat in the engine ( SOB'z). I installed a new Tsat and was doing the same thing. I then replaced the water pump, still doing it. I took both of my rad hoses off and flushed out the radiator to see if it was clogged. Nope it was not. I did the proper fill with the dex mix( left the cap off to let the air out). My cooling fans only come on with the ac on. I dont know what else there is. I really dont think its the head gasket cause im not losing coolant, there is no coolant in the crank case, no sweet smell or white smoke out of the exhaust. I am lost from this point on. Dont know what else there is to replace besides the car. please help if you can.....thanks

3100
10-25-2010, 01:56 PM
You can try testing your ECT sensor (compare ohms to temp and see if it reads right). Also make sure cap is sealing the overflow reservoir correctly otherwise pressure will not be 15psi and that will automatically lover the boiling point of your coolant.

- disregard this negative reputation: one of the moderators did not like my suggestion and decided to give me one negative point to make me look bad. I am 14year GM master tech. 3100. If my suggestion helps please give me thumbs up to fix this negative point. Thank you in advance. 3100


- also I would recommend to test your CAT if cat is clogged hot exhaust gases will have harder time to exit and will heat up engine much faster

tblake
10-25-2010, 04:24 PM
3100, you did not supply him with a value for Ohm's/temp as the normal baseline reading on a good ECT sensor. He's got nothing to compare it to.

My suggestion would be to call the seller of the car and see what he has all done to it. You could have combustion gasses getting into the cooling system which causes the temp guage to redline immediatly.

Otherwise you could swap replace the ECT sensor. Its a cheap part, under 20.00, and on the 3100 motor is a cinch to get to versus the 3800.

One question though, when you cold start your car, do the upper and lower radiator hoses stay cool to the touch and soft, or do they get firm and build with pressure immediatly?

When your temp guage reads hot, does the temp of the motor seem like its overheating? You could also have a bad guage cluster, or excessive resistance. Check the plug and wiring.

If you or you know someone that has a scan tool capable of watching data streams, you can have them plug in and see what the PCM reports your car is doing. The ECT sensor on your car is a two sided sensor, the PCM uses one side and the other side controls the guage.

tblake
10-25-2010, 04:24 PM
Also welcome to AF!

3100
10-25-2010, 04:28 PM
3100, you did not supply him with a value for Ohm's/temp as the normal baseline reading on a good ECT sensor. He's got nothing to compare it to.

My suggestion would be to call the seller of the car and see what he has all done to it. You could have combustion gasses getting into the cooling system which causes the temp guage to redline immediatly.

Otherwise you could swap replace the ECT sensor. Its a cheap part, under 20.00, and on the 3100 motor is a cinch to get to versus the 3800.

One question though, when you cold start your car, do the upper and lower radiator hoses stay cool to the touch and soft, or do they get firm and build with pressure immediatly?

When your temp guage reads hot, does the temp of the motor seem like its overheating? You could also have a bad guage cluster, or excessive resistance. Check the plug and wiring.

If you or you know someone that has a scan tool capable of watching data streams, you can have them plug in and see what the PCM reports your car is doing. The ECT sensor on your car is a two sided sensor, the PCM uses one side and the other side controls the guage.

http://www.explorerforum.com/photopost/showphoto.php?photo=30138&size=big
sorry here is the table

tblake
10-25-2010, 06:59 PM
Good Table with Useful information. I only caution you linking to other forums. I dont think the Mod's would like that very much.

BNaylor
10-25-2010, 11:05 PM
- disregard this negative reputation: one of the moderators did not like my suggestion and decided to give me one negative point to make me look bad. I am 14year GM master tech. 3100. If my suggestion helps please give me thumbs up to fix this negative point. Thank you in advance. 3100

3100,

You are only making yourself look bad so the bad reputation is rightfully deserved based on my observations and unsatisfactory replies in this forum. Your lack of practical experience on Pontiac Grand Prix models clearly shows regardless of your claim of being a "14 year GM Master Tech".

Also, since you brought it up addressing this issue in an open forum and in your signature is against AF Community Guidelines and I could ban your account either temporarily or permanently versus using the reputation system which all members to include Moderators are welcome to use. So in a timely manner please remove the comment from your signature and please refrain from addressing this issue in an open forum. See excerpt from AF Community Guidelines below.

On the AF Reputation System - Please note that you have to have adequate reputation based on various parameters to get or give good reputation so a new member has no weight on giving good reputation so asking for it is probably an exercise in futility so please refrain from doing so. At this point in time all you are doing is derailing this thread and taking it off-topic which again violates AF Community Guidelines.



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xeroinfinity
10-30-2010, 12:02 PM
mmgp3100, if you're still having troubles and your engine is not realy over heating the senor could be shot!
Here is a link that shows exactly how to test it all. ;)

GM Coolant Temp Sensor testing (http://www.automotiveforums.com/vbulletin/showthread.php?t=660655)

Hope that helps

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