my 1998 Sunfire 2.4 has been running hot lately. Believe it or not over 300,000 miles on it and very little problems. Noticed coolant pouring from the overflow and rumbling coming from the engine, evidently water was very hot. To make a long story short I changed the thermostat hoping that would fix the problem, but it is still running hot. Oil is clean and no sign of any water. My heater is pumping out hot air. Temperature gauge just below warning signs when fully warmed up. I haven't noticed any leakage from around the water pump. I know the water pump can be a pain to change, and I know that I have enough experience to do the job and get it all done right. However, it is cold outside and would have to do it in the weather. Is it possible for the impeller to be bad or maybe broken thus preventing circulation of the water. I would not hesitate to change it if the weather were a bit warmer, but forecast is cold and snow Christmas Eve so just don't know what to do. It just looks to me like the only thing it could possibly be is the water pump. any ideas?

Clogged radiator

never thought about the radiator being clogged. I guess a good flushing would be the next move? Do you think there is any way it could be the water pump? I really hate do do either in this cold, but have no choice. Thanks for the response

Luis is right, sounds like your radiator is clogged. Give it a good flush, make sure you put the right mix of coolant/water in there and you should be good. remember our cars take dexcool. I dont think the water pump is to blame, because when they go bad, they leak. II haven't heard of them just stopping since there connected to your timing chain. So I would rest assured that the radiator is just a little clogged. Also might want to try and take the car to a car wash you spray yourself and spray the hell outta the radiator and condenser on the front of your car. They are known to just get junked up with crap and can cause a running hot problem. Goodluck!

I have been trying to figure out if the radiator is clogged. I used some Prestone flush but the engine is still getting real hot. I decided to remove the upper and lower radiator hoses and run water through the upper hose and see what happens. I started slowly and the water came out the bottom hose, then I increased water from the garden hose and the water poured out of the bottom hose, it was quite clear. So, I am thinking it is not clogged and maybe the water pump is bad after all, even though it is not leaking. Don't know what else it could be, changed thermostat, oil clean with no sign of water that only leaves the water pump.

I would take it by a local auto repair shop and have them check it for any leaks under pressure and for a possible blown head gasket. Go to a reputable place though so they have the correct tools and test chemicals to diagnose the problem correctly. Cause that water pump is a pain in the a** if its the 2.4 or eco engines. If its just the 2.2 or 2200 then its a breeze and its like 15 bucks at the auto parts store. it really sounds like its not the pump. They dont really fail.

Crazy Clint wrote:I would take it by a local auto repair shop and have them check it for any leaks under pressure and for a possible blown head gasket. Go to a reputable place though so they have the correct tools and test chemicals to diagnose the problem correctly. Cause that water pump is a pain in the a** if its the 2.4 or eco engines. If its just the 2.2 or 2200 then its a breeze and its like 15 bucks at the auto parts store. it really sounds like its not the pump. They dont really fail.

The water pump does fail, seen it on a few j's iv owned. My sisters just went at 170,000. Started pissing out the hole at the bottom of the pump.

OP- this does not sound like a bad water pump as some have said already. It does sound like you have a clogged rad or a blockage somewhere. I would get some tests done before I just went and did the water pump, its a PITA and if you dont need one your wasting a lot of time and some money.


"Straight roads are for fast cars, turns are for fast drivers"-Colin McRae

thanks for all the advice and help. I think I have it narrowed down to the water pump. As I said earlier I pulled the upper radiator hose and ran water from the upper through the radiator to the lower hose, ran freely. Then unfastened my overflow hose at the overflow basin, I then ran water down through that hose, it was stopped going into the engine by the closed thermostat and the water ran freely through the radiator and came out the upper hose, so I don't think the radiator is clogged.

I then punched out the old thermostat and reinstalled it so as to make a seal between the pump and the pipe and yet allow water to move freely in both directions. I started the engine and ran a water hose into the hole where the upper hose fastens to see what would happen. I figured if the water pump was working properly then water should shoot out of the overflow hose under pressure, no water. I then unfastened the lower hose from the pipe and restarted the water and started the engine and it just ran out under gravity.

I think this almost proves that the water pump is bad and the radiator is not clogged. It just seems to me that with the lower hose disconnected and the block full of water that water should have been flying out of the overflow and then the hose.

Maybe this is a good way to test the water pump for others to use?

Now I have to get some Dexron into the block so it doesn't freeze..

Here is a question, with the car running, and at normal temp. Grab the upper radiator hose, and the lower. Does the upper feel cooler then the lower?? If so, change your thermostat. I see you punched it out, but the problem is they stick closed sometimes, and can cause a running hot condition. Since you already had it out, I would have replaced it anyways. I can bet its not the pump. they dont just stop working. On the LD9's they pee out the weep hole. They dont just stop. So it cant be your water pump. If it is it would literally be the first one I have ever seen that broke the shaft for the impeller. Since it dont sound like your radiator is clogged, try the thermostat. Its cheap enough, and with high mileage it really wont hurt. And you could also have a air pocket in the engine causing the running hot condition. If the engine was gurgling then there maybe a air pocket in there also. Just make sure when U fill it up, you let it run for some time, and have coolant ready to pour and keep the tank topped off until after it reaches operating temp and the thermostat can open fully then it will stop sucking through the coolant and the bubbles coming from the hose will stop also. Goodluck, and give that a shot.

Just because water goes from top to bottom of radiator doesn´t mean radiator is ok. in order for it to perform its duty "cooling the water", water should go through thin tubes along or betwen the fins, this tubes are what gets clogged and only way to be sure is taking the radiator tanks out and pushing a thin wire through the thin tubes, hard to do you could ask a specialty shop for an estimate. Usually if the coolant or water in the reservoir or overflow tank is dirty it is a sign the radiator could be clogged. Just in case be sure your cooling fan is on when the temp gets where it should trigger it, the problem could be its conector, its motor or else worth checking I guess.

thanks Sneezy. I bought a new thermostat two days ago and installed it but the overheating and gurgling didn't stop. I filled the overflow tank until I was sure the engine was full of antifreeze but it still gurgled. I also drove it to the auto part store twice and both times it gurgled and both time I added more water when the level went down. It doesn't seem like the radiator is plugged water went through from both directions effortlessly. The only reason I punched out the old thermostat was to make the o ring seal between the pump body and the pipe and I wanted to make sure the water could circulate either way and not be stopped by a cold closed thermostat. It seems to me like with the punched out thermostat and the disconnected lower radiator hose and water running into the block from a hose at full open that the water should have been squirting out of the lower hose, but it wasn't, it was just running out with gravity with the engine running. I don't understand it either. The guy at the auto parts store told me that he had seen instances when the impeller rusted away. Maybe I could see the impeller with a small inspection mirror and a flashlight, from where the thermostat sits, but cannot see it from below. I just don't know what to do.

The only other thing I can think to do would be to put the punched out thermostat back in and fill the water tank until water comes out the upper radiator hose hole, then I would know the engine and radiator are full from the bottom up, then reconnect the upper radiator hose, make sure the coolant tank is full and run it again to see if it still gurgles.

See this is the one thing that sucks about our cars. They are closed systems. So they are hard as hell to get all the air out of the system. If it gurgles, that means there is air in the system. Did you have your heater on while trying to fill up the system?? That also makes it keep air in the system sometimes too. And you have to wait for the thermostat to open up fully, to get the air out of the system, this does mean having the car running the entire time, with the top off the surge tank. I personally have not heard about the impeller problems with these pumps, and I have had 4 cars with the same pump and all they have done when gone bad have leaked. And they were all over 100,000 miles. Have you also tried to clean out the front of the radiator/condensor?? That will help also.

in answer to your questions. If it doesn't snow early in the morning I will again try to see if there is air in the coolant, not a nice way to spend Christmas Eve, but it is only going to get colder and snowier. I will do it exactly as you said to do it and hope for the best, but if it still gurgles I will just have to stand back and take another hard look. I have never had this problem before. I have changed the coolant and also the timing chain a few years ago so it has been coolant free a few times before and never had any problems after I refilled the cooling system.. I drove it 300 miles the night before it overheated but didn't notice any problems and it did not gurgle when I stopped the engine. Next day, all this. Thanks for the help

Have you done a pressure test of the system?? Bc im actually starting to wonder if you have a bad head gasket. I say this bc if ur using coolant and its full for sure, then something else is wrong. Have you pulled the spark plugs to see if any of them are white by chance??

Haven't pulled the spark plugs to see if anything is white, only thing white outside now is the snow and my Sunfire. I will pull the plugs though to check their color, in fact they need changing bad. One last question is about the water flow. I take it that the water flows from the lower hose to the radiator, or that's what I was told and from the upper hose into the head? If that is so then why just the trickle of water from the lower hose with a water hose full open going into the head and the engine running? I would think that the lower hose would be spewing water from the water pump, but it was just running out at gravity. Looks like won't be doing anything on this car until the snow stops and I can get it shoveled and dried out underneath. I have had lots of help in this matter and believe me I appreciate all the help and hints.