Temp gauge runs all the way to the right, high coolant temp warning light comes on...why?


Asked by Feb 05, 2013 at 07:43 AM about the 2004 Chevrolet Monte Carlo SS FWD

Question type: Maintenance & Repair

After a short time driving, the temp gauge runs high (up to 200 in less than 10 min).  Eventually it redlined at 260, high coolant temp warning light came on, I pulled over a few times to let the temp drop.  Little to no interior heat.  My coolant level is good, no leakage, what could the problem be?

14 Answers

Thermostat stuck, water pump impellers, they may be plastic, don't know if your car has plastic impellers but they wear and can break, and will not leak... and no heat in the cabin indicates the coolant is not circulating. Either will cause that. Start with thermostat, that is the least expensive fix if that is what it is

17 people found this helpful.

Thanks a lot, David...not a car guru myself, but my first thought was the thermostat...will get it checked

There is an old sort of trick that you can put the thermostat in a pan of water on the stove, boil it and see if it opens, if you are really really on a tight budget, but they are not expensive, replace it regardless. If you have never done a thermostat be very careful, if it is not seated the housing will break. Spring side down in block. Don't over torque bolts. I am not dumbing it down for you, no offense intended. I don't know if you ever have. If that does not fix it, water pump is next like I said. And your'e welcome

5 people found this helpful.

GM V6 with cooling problems - bleed the air out of the cooling system. Check the third item on this page --- http://www.gaownersclub.com/forum/faq.php? faq=maint_repair

7 people found this helpful.

Man alive, it could be a thermostat, but you need to completely flush the coolant and I'm not talking about just training it out, complete flush and clean, inspect all the hoses for spongy feeling hoses and the block and all the rest of the coolant system completely cleaned as it gets this gunk build up after a while and plugs up all the passages, then new Dexcool 50 50 ONLY as this is a GM and it's good stuff, and that GAowner club is driving me crazy, this is an Impala, lower the temperature of thermostat so it pops off sooner and check all the fins in your radiator for damage and if you see a bunch smashed in or bent up, there's a cheap little tool at Harbor Freight that you can buy and you run it through the damaged fins in the radiator allowing more air flow. Go from 180 degrees to 160 degree after the fact if your still having a problem which I doubt if you have a pro clean the coolant system professionally as they have a machine that force the coolant through all the ports and cleans all the gunk out. And if you need more detail let me know. I feel the 2004 and even still to today had a radiator that was to small. About a month ago I put a Whipple supercharger on a SS and we had over heating problems, changed to a larger radiator and a 160 degree thermostat drilled and it was perfect. That GAowner stuff is junk, this is W body car and a SS a that with a L67 the best engine ever made, why do you want to send if to some stupid Grand Am crap when he could go to RegalGS..org or more any forum for the SS period, do you get paid by the referral, I see it on every other post you make. Go to W body.com or 3800.com, you have a real car and I'm telling you this is common, Platform GM W platform Engine 3.4 L LA1 V6 3.8 L L36 V6 3.8 L L67 SC V6 Transmission 4-speed 4T65-E automatic 4-speed 4T65E-HD automatic, the wide bodies are all the same platform, just go to Wiki and search GM Wide body. But after you clean out your coolant., this is a bad A@#s car, love it, In 2004 the Dale Jr. Edition came out, it was red in color and sported a black high sport kit. The number 8, with an “E” stripe design carried from the doors to the rear bumper. The 5 spoke diamond cut wheels featured a black stripe through each spoke and Dale Jr.’s signature appeared on the right side of the trunk lid. On the sides, the vehicle received Monte Carlo SS badges. Inside on the dash a #8 badge appeared and Dale Jr.’s signature on the cluster. This edition also got #8 floor mats and headrests. This was also the first nameplate car to receive GMs L67 Supercharged 3800 V6 engine. To compete, the Intimidator Edition was re-released in 2004, this time, however the vehicle featured “Intimidator” badges on the trunk lid and both side panels of the vehicle. The car was all black in color, received the 5 spoke, diamond cut wheels and this time received GMs L67 Supercharged 3800 V6 engine.

5 people found this helpful.

Tenspeed has it right when air gets trapped in the water pump the impeller fins can no longer circulate the coolant. There is a bleeder screw by the water pump. Open it to let the air out of the system. Close it when coolant streams out of the bleeder screw. If that does not correct the problem you will need to flush your coolant system although that is rarely the problem.

4 people found this helpful.

What was the problem because i'm experiencing same problem with same car

3 people found this helpful.

I'm experiencing the same problem on my 02 buick rendezvous cxl.. I just replaced the thermostat this morning, washed her and waxed her, got her ready for a 45 min drive to test her out and b4 she even got on the highway my Guage slowly but surely climbed to hot and "hot coolant temp" is all u hear from the dash.. could it be the coolant temp sensor?

8 people found this helpful.

It could be a couple of things depending on the condition and miles and type of motor. It could be caused by a faulty or shorted out sensor it is common for them to fail gm uses alot of diferent high amp electronics its always good to check and clean battery teminals wires bad grounding or a weak battery can fry the relays or sensors . but I've noticed that it is a melted or dry brittle broken wire some soldering and shielding and your set. It may be due for a coolant flush i dont know if it still gm changed the formuala of dexcool but it is infamous for developing a sludge when antifreeze levels are low it oxidises when exposed to air and heat also it will have a simillar reaction when mixed with different types of antifreeze I have done alot if coolant flushes and repair work because some owner or kid at jiffy lube put in the green stuff instead of orange dexcool also is just a rumor I've heard from other mechanics but it may eat away and shorten the life of plastic gaskets I flush it out and use regular coolant personally. Most likely though due to the age and the motor designs mostly the 3.4 it could have air pockets in the system there can be two to 3 different bleeder valves that need to be opened to get all of the air out properly. It could also be a stuck thermostat and if its loosing coolant most likely the lower intake gaskets the water pump or worst case head gaskets. Sometimes rare but I have seen it happen with the 4t65e transmission it could be the transmission overheating and the atf fluid could be causing it the transmission cooler is built in to the radiators of most gm models of those years I personally install a auxiliary trans fluid cooler in line with the stock one.

1 people found this helpful.

What's it mean when the temperature reads low

1 people found this helpful.

I can go 20 30 mins then it try to run hot. I put a new water pump and everything what could that be

5 people found this helpful.

What is the problem on my 2000 Monte Carlo? The temp goes up to the hot and then the heat gets cold and then the heat gets hot and the temp goes down!! Help

10 people found this helpful.

Most people suggested the simple basic causes. The most common problem for this is a head gasket. Driving down the road, Temp spikes up. Why? Compression leaks through the head gasket into coolant passage. During this time you will seldom have a working heater due to air the bubble sitting at the water pump and coolant not circulating. The over heat problem maybe short or prolonged. Some vehicles will spike up, bubble out the air pocket through the over flow, coolant hits the water pump again and cool right back down until the next bubble forms. Others will stay hot until you pull over, let cool and either top off the radiator or allow the coolant to pull back into the motor from the over flow tank. Some require bleeding the upper system and many have a bleeder or two for letting the air pocket out. If all the basics seem fine. No coolant leaks, Thermostat is fine,no thrown pump belt. I would say head gasket is bad. 9 out of 10 times I find a bad head gasket, cracked block, or head. I made a pressure gauge to put in coolant system to watch coolant pressure while driving. Each time I use on a different vehicle I find a way to adapt it into the system. Biggest give away with a bad head gasket or cracked head or block is system builds pressure even before engine gets warm and pressure keeps climbing until the pressure is let off by the pressure relief cap on radiator. As the pressure builds the temp will remain normal until the air bubble causes a air pocket somewhere in the system. When the air hits the water pump all coolant stops flowing and up shoots the temp due to steam hitting temp sensors. Aluminium heads and blocks often corrode and the fire ring on the head gasket looses its seal. Back in the days of cast iron heads and block the problem was not seen as often. Some vehicles are just pron to head gasket problems . Changing coolant from new on to keep the coolant from becoming corrosive can help. The newer coolants seems more corrosive to me anyway. On my vehicles I drain out the new coolant around 36,000 and put in the good old green and never lost a gasket and keep driving them until they rust out or major mech. issue.

in addition to above, Slow flowing coolant due to sludge will get hot at a slower rate. You will not see spikes up and down with plugged radiator. One sign of bad separated coolant is sludge seen when you remove radiator cap. Also you may notice heater just does not heat like it used too. If anyone knows of a good flush to remove the sludge from the new coolants that are supposed to be so good let me know. I have tried about a dozen off the shelf flushes and never found one that works on the new coolants. I always planned to take some of the sludge and try different things to dissolve it but always forget to save samples. I'm thinking something like toilet bowel cleaner might be needed to break up the sludge. Vinagar? Simple Green. Something must work.

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