What Would Make A Car Run Hot?

[NDL]

I'm trying to figure out what's going on with my Wife's Century, with the 3100V6. The car has been running hot for the past four months - with the temp needle going 3/4 of the way towards H.

I recently replaced the thermostat, which seemed to have helped for a week, but now it's running hot again.

Here's the thing that puzzles me: The temperature of the motor is affected by highway speed. In other words, the car will run hot @ 55 mph - yet the engine should be running at only 2,000 rpm's (nevermind all of the fairly cold air rushing through the radiator).

Now that it's getting warmer, I plan on flushing the system, and seeing if that helps a bit.

The fan is working properly...

Thanks in advance for any help/suggestions!

[z28luvr01]

Another bad thermostat?

Also, there could be an air bubble in the system that got introduced when you changed the thermostat. That usually happens. Check the coolant level in both the radiator and the overflow jug. Assuming the thermostat is good, run the car to operating temp in the driveway with the radiator cap off. When the thermostat opens you'll see the coolant level in the radiator drop (some will no doubt spill out before this happens). Then pour some more coolant in until its near the top. Finally, put the cap on. When the car cools, the unneeded coolant should go into the overflow jug.

[scharmer05]

last summer my car started to run hot too, i took it to a couple guys and they threw parts at it without anything helping. finally one day this last fall i started it up and took off and had almost no power. Turns out it was my catalytic convertor all along. It had been plugged somewhat pretty much all summer and finally plugged up enough for me to notice.

[the_yellow_dart]

When this happened with my 3.1 Lumina it turned out that something was wrong with one of the pistons, and my coolant was burning off. The system was overheating due to there being almost no coolant left. Hope that's not what's happening to you.

[NDL]

Thanks everyone, for the helpful replies! Z28luvr01, I doubt if it's an air buble, because after installing the new thermostat, I did exactly as you wrote. We'll see if that's the problem however, as I plan on flushing the system in a week or two...I'm hoping that it is.

[76ChevyTrucker]

On the Chevrolet 3.1L engines, there is a bleeder screw on the metal pipe the runs from the water pump housing to the thermostat housing, open up the bleeder screw and bleed the air out of the system, a lot of times air will get trapped in the system (yes, even with the radiator cap off) and you have to burp the air out of it from the bleeder valve. Another thing is the troublesome intake manifold gasket problem that the 3.1s and 3.4s have......

[Sixty8panther]

What Would Make A Car Run Hot? Internal Combustion.

Alright all joking aside, here's a possibility: clogged heater core, radiator or a bad water pump. If the coolant is not circulating throughout the block it's pretty much useless except if you want to boil antifrreeze.

[NOS2006]

On the Chevrolet 3.1L engines, there is a bleeder screw on the metal pipe the runs from the water pump housing to the thermostat housing, open up the bleeder screw and bleed the air out of the system, a lot of times air will get trapped in the system (yes, even with the radiator cap off) and you have to burp the air out of it from the bleeder valve.  Another thing is the troublesome intake manifold gasket problem that the 3.1s and 3.4s have......

Add 3.8s to that list.

[76ChevyTrucker]

NOS, I'm trying to NOT remind myself that the intake on my 3.8 will eventually start leaking......

[NDL]

Alright all joking aside, here's a possibility: clogged heater core, radiator or a bad water pump.

Sixty, thanks for the suggestions...If it is the radiator, I am hoping that flushing the system might help some (enough).

[NDL]

On the Chevrolet 3.1L engines, there is a bleeder screw on the metal pipe the runs from the water pump housing to the thermostat housing, open up the bleeder screw and bleed the air out of the system, a lot of times air will get trapped in the system (yes, even with the radiator cap off) and you have to burp the air out of it from the bleeder valve.  Another thing is the troublesome intake manifold gasket problem that the 3.1s and 3.4s have......

76Chevy, thanks for your help. Here's what might seem to be a stupid question, but it's better that I ask, than to run into trouble: Do I bleed the system with the motor off, or on? Warm or cold?

Thanks again

[76ChevyTrucker]

engine running, gotta have someway to push the air out of the system without introducing more into it (the risk you run with just doing the open radiator cap burp). As far as warm or cold, that's your decision, do you want to burn your hands on hot metal, or not? And there is no such thing as stupid questons, unless you consider the ones that are NOT asked.

[NDL]

engine running, gotta have someway to push the air out of the system without introducing more into it (the risk you run with just doing the open radiator cap burp).  As far as warm or cold, that's your decision, do you want to burn your hands on hot metal, or not?  And there is no such thing as stupid questons, unless you consider the ones that are NOT asked.

76ChevyTrucker, thanks again!

[Guest Josh]

No no no no no as with my '93 Grand Am for some reason the wires became disconneted from the fan blower. Check those. If it's good at highway speeds it's because the fan moves due to the air coming in which cools the engine.

Check that first.

[scharmer05]

NOS, I'm trying to NOT remind myself that the intake on my 3.8 will eventually start leaking......

My old car, 95 bonneville, which my sister was driving after me started leakin antifreeze and my sis never bothered to check it and eventually burned up the engine...idiot

[76ChevyTrucker]

I keep an eye on everything daily, so I'm more than sure I'll notice whenever something appears amiss.

[lauren]

What Would Make A Car Run Hot?

stolen parts.

[capriceman]

Last Saturday I had a similair problem. I had a leaky radiator, So I order one it ends up being $140 but then they gave me some performance Visteon aluminum core raditor. Then changed the Thermostat and lines. I noticed that my raditor was clogged with crap. Which cause's heat build up.

Another thing that causes heat is low transmission fluid or Transmisson problems since most cars combine the transmission cooler and raditor. If your Engine overheats so does your trans and vice versa.

Also a Clogged A/C coil will cause not enough air to flow to the radiator.

Also If you keep the throttle pinned it cause excessive heat to. :AH-HA_wink:

[Buickfosure]

Also to add on make sure when ever you add antifreeze mix it 50/50 or 70/30 in really cold climates... Many people know this yet I still see many people that buy straight antifreeze and just fill their whole radiator with it. Antifreeze doesn't have the cooling properties of water and if you happened to be unaware and just added 100% antifreeze that would cause you some overheating it would still cool but not even as effective as a 50/50 mixture. You can get away with a 70/30 mixture but I only recomend that if your car is exposed to some really cold temperatures otherwise 50/50 is best efficient mixture. Also i've started to use the distilled water when I replace my radiators for the reason of not having the minerals normal tap water has that clogs up a radiator over time and making it less efficient. Also the fail safe thermostats I like them too it can really save you alot of trouble becasue if it fails wide open you will not overheat your engine and won't be stranded on the side of the road. I always like to put quality parts into my cooling system because an overheat can really hurt your engine especially all the cars without a temp gauge you find out your car is overheating right as the steam rolls out and then your dummy light comes on.

Edited April 1, 2006 by reeferman