Engine Overheating

Hello Im having a bad time with my coolent system. i have changed just about everything the water pump, thermostat, radiator, intake manifold, and 2 elbow joints located under the intake manifold. i have blow my head gasket but had it fixed.

Have the cooling system pressure tested (make sure they remember to check the heater core along with everything else). This check should include checking the radiator cap!

During the system pressure test, a good system (with no leaks) should hold pressure for 2 minutes or more. The cap should do the same.

I have replaced the radiator, water pump, thermostat and thermostat sensor. My car goes to the hot side and turns off soon after starting to drive. it has plenty of water in it. It does not steam. I do not know what is wrong. Also I have had the head gaskets checked they are good. And when I push on the gas I hear a grinding noise. Please help me!

Hi, does the engine seem hot? I am thinking it could be the engine temperature sensor or loose connection at the sensor which would cause the problem. Do you have a manual sensor like this?

www.2carpros.com/articles/how-to-use-an-infrared-temperature-meter to see if is really overheating?

Engine Cooling problem
2003 Chevy Impala 6 cyl

I have changed the water pump do to leakage now the car wants to heat up over 200 easy.But i can turn on the heat and it cools down,however when i turn on the ac it cools down alot faster like a steady drop to 160 -170

Check cooling fan may not be coming on with engine temp but does with AC. Check out fan relay and temp sensor.

hasnt been long maybe 5 months replaced the relays for the fans and 1 of the fans also.Are you talking about the sending unit on the radiator or the temp gauge?or is that the same one?

ECT located near coolant outlet left rear engine Do fans come on with engine temp?

yes the fans come on however they go alot faster with the ac on.Also i didnt bleed the air out of the lines looking to that now.My heat inside the car doesnt seem to be as hot as it should either.

Engine Cooling problem
2003 Chevy Impala 6 cyl Automatic 100000 miles

just chgd thermastat, since that, heater puts out proper heat when idling, then cage drops down to 140 when driving, and gives out a little heat. had a coolent flush. still no chage

sounds to me like you may have put in too cold of a thermostat, try to put in a higher temperature rated thermostat.

I bought this car in January of 2009 and since then it has been overheating constantly. Thankfully I don't need to drive it everyday, but I have put a hefty sum of cash into the vehicle and was hoping someone could give me the best prognosis for my problem.

First note - In the winter the car barely overheats, I assume due to the weather outside.

When does it overheat -
After 40 minutes of driving 65 mph +
Stop and go traffic
Idling

What I have fixed/done -
New thermostat/Radiator fan/Multiple Heater core and Radiator line flushes/had Head gasket checked, came back negative

Other symptoms -
The heat in the car will stop working and I will get a heater core flush hopefully to allieviate backed up hot air, not sure if this can cause overheating

After flushing out the radiator it appears to help, but uncertain, most machanics say that there is build up and sludge, one said it was rust piling up in the lines (is there something I can buy to get rid of the rust?)

The coolant can be murky, but does not smell like oil

Whats next -

I just don't know what it could be anymore, flushes seem to work, but that could be the introduction of new coolant into the system and very temporary. Could it be the intake manifold, which I read is bad on this model car, how would I check that?

Any other suggestions?

Thanks!

Hi DP978,

Thank you for the donation.

When overheating occurs and the radiator fans do not stop after starting, then the cooling efficiency is poor. Possible causes are :

1. Weak water pump.
2. Clogged radiator, normal flushing would not help, you need to remove the raditor to get the core internal lines cleared.
3. Bad thermostat. It is not opening sufficently.
4. Cooling fans not working.
5. Insufficient coolant in system.

Coolant should not be mixed, ie. different brands in the system can cause clogging.

If the coolant is murky, it means the system could be clogged somewhere or has a lot of contaminants in it. one of the best way to check fior clogging and the condition of the coolant flow is to remove the thremostat and run the engine. If you can see the coolant flowing fast in the system then the water pump should be ok.

Let the engine run and replace the coolant with water to clear out any contaminant. Repeat a few times, each time allowing the water in system to heat up, which will then be able to clear the contaminants. A good radiator flush would help. It would be best to do the flushing over a period of a few days (without the thermostat to check if it is the cause).

Once the water in the system loooks clean, you can proceed to replace with coolant if it is not overheating.

Thank you for the response -

Can I ask a couple simple follow ups - I am by no means a mechanic or gifted when it comes to anything cars.

Just a few weeks ago I got both 1. A radiator flush and 2. my Coolant drained and replaced (so there should be no issue of mixed coolant brands).

After a couple of drives the coolant under the radiator cap is green with lots of specks of brown (does not smell like our) which a am assuming is rust or something that is making it murky.

Although I am not sure I would know how to 'remove the thermostat', I would want to check the flow of coolant, but how would I go about seeing if the coolant was 'flowing fast' or not? (Would I undo the radiator cap and see if anything flowed in there?)

Also, regarding your last paragraph about flushing it out with water, how would I go about replacing the coolant? Would I let the coolant spill out the radiator cap and pour in water in replacement? Or would I drain the coolant sommeplace else and put in water as it runs?

Edit: Should the fans come on immediately when the AC is turned on? It appeared that they were not turning, they are visible from the back of the radiator, correct? (the car was running at 220 f at this point)

Thanks for your help, I will definately be able to donate more once I am closer to some sort of answer.

The brown specks are an indication of contaminants and it could be rust or other foreign materials.

As to the overheatng, if the cooling fans are intermittently coming on and off, it could be caued by the Body Control Module or the charging system. There was a service bulletin out on this problem so I would suggest testing/checking if the cooling fans are working correctly as you have done the flushing so many times before.

Get the charging system tested to see if it is good.

The cooling fans should come on when the AC compressor is running. For some models there might be a slight deley at initial startup.

To flush with water, you would need to drain the coolant ut and refill with water.

To remove the thermostat, you would need to remove the thermostat housing located in fron of engine.

First I have replaced the water pump and thermostat. and the water temp would get real hot then all of a sudden it would drop down to cool then it will go back up then back down. What could cause this. Thanks Frankie

Air in the cooling system.

1 1/2 years ago had the head gaskets replaced, they were the cause of overheating. Now it's overheating again. The water pump and thermostat have been replaced, the lower radiator deflector is missing. when I drive the car it will go to 210-220 I will then park and let it idle temp does not come down until I turn on the A/C the fans kick on and the temp comes down to normal. when the car was cold I drained some coolant out so I could see the first row of the radiator. With the cap removed I started the car when it got to normal temp I could see good flow out of the top row of the radiator. If I start the car and let it idle for at least a half hour it will run at normal temp never getting hot

Hi grey-hair. Welcome to the forum. Sounds like a problem with the coolant temperature sensor if the radiator fan doesn't turn on without having to turn the AC on. To verify the lack of a fan is causing the overheating, next time it runs too hot, turn the heater on maximum hot and fan on high. That will act like a small radiator.

Also check for multiple fan relays in the fuse box under the hood. Some cars have a low and a high speed relay and some have one for just the radiator fan and another that runs both the radiator and the AC fans. A fast test for relays is to switch two indentical ones around to see if a different circuit stops working.

Some vehicles, minivans in particular, use an electronic fan relay module with multiple inputs. That would also be a likely suspect.

caradiodoc

I just drove it 50 miles on the highway at first it was ok then comming back it ran at 210. Shouldn't ram air at 80 mph be sufficent airflow to keep it cool? just now I ck'd the temp sensor and it has 5 vdc to it and through the sensor I see an open circut, I only had one fault and that was po420 I replaced the downstream o2 sensor and cleared the fault. If the temp sensor is bad shouldn't that show as a fault?

Sorry, the temp sensor is good I had the meter set wrong. It was 1400 ohms at around 100 degrees.

Sorry I missed your replies. I was out of town at the nation's second largest old car show swap meet.

1400 ohms is acceptable for the coolant temperature sensor but the 5.0 volts is not unless you measured that while it was unplugged. If you back probe the connector while it's plugged in, you should find between 0.5 and 4.5 volts. The higher the temperature, the lower the voltage. By the way, are you on a two-wire sensor? If it only has one wire, you're looking at the sensor for the dash gauge.

The fan should not be needed at highway speeds. If turning on the heater fan helps, check the radiator for corroded and crumbling cooling fins.

caradiodoc.

So I have a 3400 model and I recently purchased the car for cheap due to the previous owner trouble shooting and not being able to find the problem with elimination i have narrowed it down to being something with the cooling system of the car. It acts like it is overheating, the overflow tank fills up to the top and the coolant gets hot, however if I drive with the heater on this issue does not occur as if it is overheating. the temperature gauge stays normal and fluctuates as it should never going over halfway no matter how long the drive. 150 on all cylinders, the car is fine and runs smoothly, just this little hiccup with the cooling system, can anybody help me find out what it is exactly? Thanks

Inspect the cooling fins on the radiator to see if they are badly corroded. That will prevent them from giving up the heat to the air. The clue is running the heater reduces the overheating. The heater core is a small radiator.

A leaking cylinder head gasket is always a good suspect too, but you would be losing coolant, and you did not mention that observation.

All gaskets are brand new and nothing else is having issues at all, car is smooth as heck. basically the only problem I am having is the overflow tank overflowing literally. lol. also, the low coolant light comes and goes but definitely not out of coolant. I have been told it could be the thermostat, water pump and some sensor within the cooling system. any other thoughts or possibilities?

Also one final helpful hint to the issue maybe. No codes pop up on my reader and it works fine if that helps. no codes read.

You said the problem does not occur when the heater is on. That eliminates the thermostat and water pump. Everything is working properly at that point.

The only other thing you did not mention is if the radiator fan is turning on. Your model should still have two coolant temperature sensors. One is for the dash gauge. That one will not cause an overheating problem. It only reports coolant temperature. The other sensor is for the engine computer. Both of them are extremely reliable because they have just one part inside them, but corrosion on connector terminals, or other wiring problems can cause it to report a temperature that is too low, then the computer will not turn the fan on. The clue to that is the overheating will never occur at highway speeds where natural air flow is sufficient.

So then your saying the problem pretty much has to be either the second sensor you mentioned or the radiator fans? I have considered the fans as the issue, however they somewhat seem to work, but in my opinion very poorly. Is this something you would bet on? Because I am clueless at this point. lol, just do not want to waste the money on something that will not solve the issue. you have been very helpful and I appreciate your time though.

Engine Cooling problem
2000 Chevy Impala 4 cyl Front Wheel Drive Automatic
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I have replaced my water pump , the radiator, and the thermostat, after all i have replaced my engine still keeps running hot on me, what else could be the problem?

Have you actually check that your engine IS hot with a thermometer?

It could be that you have a bad temperature gauge, a bad sensor, or a bad connection in the wiring or something.

How is your coolant level? maybe you have a leak somewhere (internal/external). I suppose that's the first thing you checked though.

Other possible problems:
*you serpentine belt is slipping on the pulley resulting in the water pump no working properly (check you tensioner). Speaking about pulley, your water pump pulley is the original one right? (or at least an original replacement, same size etc...).
*bad hoses
*your electric fans don't come on
*bad radiator cap
*glogged water jackets in your engine

Since you've replaced the water pump, radiator and thermostat, these are the other reasons I can think of.

I suggest you pressure test your cooling system to check for leaks.

That was not a typo. Check the cooling fins, not the fans. If you can get to the front of the radiator without the AC condenser being in the way, rub your fingertips over the fins and see if they crumble like a rotten chocolate chip cookie. This is especially common if you live in a state like I do where they throw a pound of salt on an ounce of snow.

This happened to my 1988 Grand Caravan when it was twelve years old. The temperature gauge would start to creep up at anything over sixty mph and sixty degrees. I drove it from Wisconsin to Denver, but it was mostly night driving when the temperature was cool, so I did not have a problem. By two yeas later, it even ran too hot when it was thirty five degrees. The fan turned on like it was supposed to, but the air flow did not do anything.

I used that van to drag around a tandem-axle enclosed trailer that was bigger and heavier than the van, and with that radiator, I could keep the temperature down by running the front and rear heaters on high. Problem was I was taking that trailer to the nation's second largest old car show swap meet which is always the first weekend after the Fourth of July, so it is always hot outside. Running the heaters is not what you want to do on a hot summer day! I finally had to get a new radiator. I patched so many holes in it that I was spending more time at that than sleeping! With the new radiator, the temperature stayed normal, even when pulling that trailer on a hot day.

The car did originally come from Nebraska in fact. okay, you have been very helpful good sir thanks for your time and information man I appreciate it.

I have inspected the radiator and it is also fairly new. very clean. So now I am back at square one. lol, help! I am stumped at this point. the only thing I can think of is the second sensor this mechanic mentioned, does anyone else have any opinions?

Next I would perform a chemical test at the reservoir to check for a leaking cylinder head gasket. That involves drawing air from the reservoir, while the engine is running, through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.

It may be less expensive to have your mechanic do this test. You might be able to borrow the tester from an auto parts store that rents or borrows tools, but they typically make you buy your own bottle of liquid That is because the liquid is rendered ineffective if it is allowed to freeze or if it becomes contaminated with coolant. That would cause it to provide incorrect results for the next person who borrows it. The test usually only takes a few minutes. A bottle of the special liquid may cost more than the cost of the test.

Car thermostat hits the red within ten minutes of running. Changed the water pump, thermostat, flushed radiator and bled the system. Both hoses that go to the heater core never get hot. When i bleed the thermostat bleeder, only steam comes out, never liquid. This hose gets warm, not hot and has a "bubbling" feel to it. Same feeling on one of the hoses coming from the heater core. Radiator does not leak, ran the car with the radiator cap off to see if that would help clear air from the lines. Nothing has helped at all. What's next?

Take the radiator out and get the core cleaned a flush may not be enough if you have blocked core tubes, also test the thermostat in a pot of boiling water just to make sure that it is opening.

My car keeps overheating like all the way to red and car loses power. I just replaced radiator, thermostat, cooling fans, new battery, radiator hose. And yet it still overheating. I dont know why? Im single mom so i dont know much bout cars can you help me. All parts replaced were bought brand new from napa...

The very first thing you probably should learn is, don't let the car overheat........... ever.
If you drove it hot to the point of losing power and by the sounds of it you did it more than once, you have likely done serious internal engine damage now such as a blown head gasket or cracked head.
You may have had a small problem to start with but driving it hot has developed into something far more serious.

supposedly the Impala's have the overheat protection where when the engine is in overheat mode the PCM squirts gas in every other compression stroke instead of every, allowing the engine to not overheat . when does the car overheat highway or around town. Could be the electric fans. see if their fuse/relays are ok. Let the car idle the fans should come on around 200 -220 .

forgot , are you loosing any fluid. if you have a leak the coolant system can not pressurize and hence the coolant turns to steam.