Engine overheating

Stuck closed thermostat, inoperative cooling fans, internal leak from blown head gasket or crack, low coolant level, no water pump/broke belt/seized, clogged radiator. A pressure test, and a block test for presence of combustion gases in cooling system would be a start. More specific information on under what conditions it overheats might provide some insight.

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Check out this guide

Or try having your mechanic take out the radiator and send it to a radiator repair shop. Most likely you have a plugged radiator specially if you use that orange colored Delco antifreeze. That type of antifreeze is more of a sugar base antifreeze, and if you do not replace it every two years it will end up plugging up the cores in your radiator. I had a Cadillac that that happened too. And when I took the radiator out it weighed close to 40 lbs it seemed like. Took it to a repair shop and they took the tanks off and boiled it in a acid bath and cleaned the cores and replaced it with new tanks and my over heating issue was solved.

Great addition to this thread! Please feel free to help out whenever you are on the site. :)

Cheers, Ken

Okay it is weird. My dad had got the car from a good friend of his. When he first was testing it out the first day it ran hot but when he cleared out the glove box it was fine. Three weeks later I bought it after him checking it out and one week after I got it, it ran hot on me going to my dads. Now I had went like 20 to 30 miles one direction sometimes longer. Well we figures since it has a brand new water pump and fans we changed the thermostat it was fine after that. Drove for about a week and then on my way home ran hot on me again. Coolant light never came on before this so there is no leak. Ran hot so it boiled the water out. Okay someone stopped and helped us and we put water in it and temperature was fine the whole rest of the way home. The next day fine too, went a long distance to Lafayette and back which is like 20 to 30 miles there and the same back. never ran hot back and forth to work for two days never ran hot. Checked the coolant levels before I left and it was fine. On my way back home last night ran hot again on me. After we put water in it was fine, today fine. Can anyone help me?

The heads have been checked and are good. Everyone that I talk to says that it seems that is is the problem being that it is a Northstar engine, but they have been checked.

Has system been pressure tested?

Exhaust gas tested?

How did you check the heads? They sell a kit that sniffs the coolant for hydrocarbons in the coolant. Is it low when you check it after driving? Does it seam to boil out of the coolant jug?

My car has been overheating the last couple of days because it has been hot outside. Will green antifreeze instead of Dexcool make it overheat?

Will green antifreeze instead of Dexcool mess up my engine or make it overheat? I just bought this car and it has green antifreeze in it and since it has gotten hot outside last couple of days it has been overheating.

the water is not low....and they checked it with that tube looking thing.....it does seem like it's boiling out of the jug....there was a leak and it was fixed...the leak was where the water hose hooked to the radiator. but theres no more leek

We call the red Dex-Cool "Dex Mud" because that is what it can turn into. The green will be fine but it cannot be mixed with the red. The system should have been flushed when the change was made.

First check that the radiator fan is turning on. Check the fins on the radiator to be sure they are not corroded away.

The heads should have been check.

Any lights on? How it over heating? Bubbles in the jug?

Try having your mechanic take out the radiator and send it to a radiator repair shop. Most likely you have a plugged radiator specially if you use that orange colored dex cool antifreeze. That type of antifreeze is more of a sugar base antifreeze, and if you do not replace it every two years it will end up plugging up the cores in your radiator. I had a Cadillac that that happened too. And when I took the radiator out it weighed close to 40 lbs it seemed like. Took it to a repair shop and they took the tanks off and boiled it in a acid bath and cleaned the cores and replaced it with new tanks and my over heating issue was solved.

You need head gaskets! Call me I can help. 610-529-1346 -Jim

I have a 98 Cadi Deville, the car was runing ok but now it is overheating. I put a new radaitor in the car becuse the top D/S of the radaitor wasn't getting hot and i thought it was cluged. After that I changed the water pump & thermostat. The car was runing good again for a short time, but now the radaitor is getting hot like normal. It takes time for the car to overheat but it still overheating. There are no signs of a bad haedgasket, no white smoke, or pressure biulding up in the coolant system. So I ask for your help with this problem.

By signs of a blown headgasket, what signs are you looking for? If your coolant level is full, and your cooling fans are functional, coming on around 212, then I would recommend having the cooling system tested for the presence of combustion gases. Mysterious overheating conditions that are not corrected with normal service procedures(T-stat, external leaks), are most often result of leaking head gaskets. With the mileage that you have on the vehicle, and not knowing whether thread repair has been performed on the head bolt holes, make it more of a legitimate possibility. There may or may not be external signs, like white smoke, leaks at the sealing area, or excess pressure, to indicate. Especially since it takes time to overheat. The signs you may be looking for are indications of accelerated problems.

this car has been having overheating problems since i got it about 3 weeks ago. we have changed the thermostat....talked to the mechanic that the car was brought to and he says it's unsolved mystery with this car....he changed the water pump 3 times and has pressure checked the car leaks and tested for head damage...everything is fine...changed the thermostat numerous times....he has even aked advice from like 3 other mechanics and they can't figure it out.....well this is the problem....the car doenst run hot till after about an hour of running it constantly....the water i guess boils out of it when it runs hot and we put more water in it and runs fine for another hour...or so.....checked the fans also...they come on when you turn the ac on...we have even tried to connect a toggle switch thinking maybe it don't come on sometimes....dindn't fix the problem...checked the purge line and it's fine....and the hoses aren't collapsing....can anyone suggest anything or give any answers to what seems to be the problem...also when he takes the radiator top hose off and puts it in a bucket no water comes out until it heats up which i guess the thermostat is opening up and just a little comes out....when he accelerates the car more comes out and then it just stops....could the radiator be plugged or is it something else.

Check for cold spots on the radiator if any its clogged-up and also try bleeding the cooling system-if all else fails-block and pressure test it-

Try having your mechanic take out the radiator and send it to a radiator repair shop. most likely you have a plugged radiator specially if you use that orange colored delco antifreeze .. that type of antifreeze is more of a sugar base antifreeze, and if you dont replace it every 2 years it will end up plugging up the cores in your radiator . I had a Cadillac that that happened too .. and when I took the radiator out it weighed close to 40 lbs it seemed like . took it to a repair shop and they took the tanks off and boiled it in a acid bath and cleaned the cores and replaced it with new tanks and my over heating issue was solved .

my car was running very hot and started to overheat. i brought it in to my mechanic and they replaced the thermostat. but it is still running hot. they said it's not getting a tight seal on the cap even though they replaced it with a new one. they said i might need a 18PSI instead of a 16PSI. i went to pep boys to get one but they said a 16PSI is good enough. what do you it might be?

Check the radiator if its clogged-up and water pump circulating coolant thruout the engine if both okay try bleeding the cooling system don't work get it block and pressure tested.

thank you for the advice. what are your feelings on the radiator cap? the 16psi as opposed to a 18psi cap?

16 or 18 psi it doesn't matter versus the OEM part the idea behind it is to hold that pressure

Did they pressure test the old cap? again block test it and go from there that's if the water pump and radiator are in working order-could be very well be airlock in it-who knows????

Try having your mechanic take out the radiator and send it to a radiator repair shop. Most likely you have a plugged radiator specially if you use that orange colored dex cool antifreeze. That type of antifreeze is more of a sugar base antifreeze, and if you dont replace it every 2 years it will end up plugging up the cores in your radiator. I had a Cadillac that that happened too. And when I took the radiator out it weighed close to 40 lbs it seemed like. Took it to a repair shop and they took the tanks off and boiled it in a acid bath and cleaned the cores and replaced it with new tanks and my over heating issue was solved.
Thursday, September 27th, 2018 AT 7:38 AM

Vehicle overheats after it is driven for a while. What could be the main problem and if it is reasonable in terms of repairs costs.

Could be low on coolant, that would be the most inexpensive. Before I spent any money to address it, I would strongly recommend the cooling system be checked for the presence of combustion gases. This would indicate an internal leak, and could bein the range of $3000 or more to fix properly.

Engine Cooling problem
1998 Cadillac Deville V8 Front Wheel Drive Automatic 145000 miles

Q. Vehicle overheats after it is driven for a while. What could be the main problem and if it is reasonable in terms of repairs costs.

R. Could be low on coolant, that would be the most inexpensive. Before I spent any money to address it, I would strongly recommend the cooling system be checked for the presence of combustion gases. This would indicate an internal leak, and could be in the range of $3000 or more to fix properly.

Q. Would "Steel Seal" product work to fix such a problem?

In my honest opinion, I am not real supportive of additives, but I am in the repair business. Will it work, I don't know. I have never had any experience with anyone who has used it.

I will give you this scenario. Assuming that it has an internal leak, the cause is aluminum thread failure in the head bolt holes. Could be one, two, or several, on one or both banks. A sealant is possibly going to help the current leak, but will not restore the retention(clamping) of the stripped hole. What is likely to happen, is holes around the stripped one are going to fail, as they are more relied upon to sustain the load. This comes from heating and cooling, expansion and contraction.
A lot of the reason I don't support additives, especially in the cooling system, is this. You add it to a tank, with not alot of turbulent water flow. The heavier portion of the substance is likely to settle to the bottom. If in fact it does make it main stream, is the leak bad enough that it is going to seek and plug it? I have seen more of the sealants trapped in the bottom of radiator tanks, and blocks. It could lead to increased cooling system temperatures, and a higher potential for overheat.

The assumption that you have an internal leak is just that at this point. You would need to have it tested to confirm. A block test is best done with a gas analyzer, like the one used for emissions testing. Roadtest the vehicle until warm, have the gas analyzer at the filler when the cap is removed. Any reading over 100 PPM hydrocarbons indicates a cause for concern. As far as Steel Seal, on a consumer basis you could give it a try. If money, or repair costs exceeding the value of the vehicle are a concern, it is your best option.

I have an 98 cadillac deville that over heats i changed radiator,thermostat,radiator cap and its not the water pump...please help

Don't waste anymore time, or money, until you have a block test done for the presence of hydrocarbons in the cooling system. Aside from the occasional thermostat stuck closed, failed W/P belt tensioner/belt, and low coolant level, internal combustion leaks are the major cause for overheat on these engines. The head bolt threads in the block were a poor design from 93 up until about 2004 when the thread pitch was increased.

Thank you for responding now I'm being told its the intake manifold could that be correct

Coolant does not flow through the intake manifold, nor would it cause an overheat. There is a passage through the throttle body that can plug and possibly cause an overheat, but it is somewhat rare. If you are not confident in who is giving you the diagnosis, and they have yet to do a block test, I would urge you to demand a test before spending anymore money. If they don't know how to perform the block test, or are not equipped, find someone who is. I would be willing to bet that it has leaking head gaskets(internal) due to pulled head bolt threads.

I noticed my 1998 deville was running hot. I replaced the thermostat. The car still is runnig hot but it cools down as i drive it.The water pump is working but the fans come on when it reaches 230 degrees. Do you think the thermostat is bad or the fans need to be replaced?

Hi:
If you replaced the t-stat, chances are it is ok. If the fans are working, they sound ok. Does the engine cool down when the fans turn on? Have you ever had the radiator flushed?

Let me know.

Joe

Yes at about 230 degrees both fans come on and the engin starts to cool down. Iam going to flush the radiator now.Hope that it will take care of the problem.Thanks for now

what else could be causing my engine to overheat after i installed a new radiator and a new water pump aith a new thermostat?

your engine coolant temperature sensor could be faulty.have it checked/replaced. this sensor, tells the computer what the temperature of the coolant is so that it will turn the fans on when it becomes too hot.

would the wrong radiator cap cause the car to run hot and overheat? i have a 20psi cap on the car and i have been told all i need is a 16psi. i have a new water pump, thermostat and radiator. and it was block tested. would the extra pressure form the cap cause it overheat? i would appreciate an answer because this is driving me crazy. the car is great otherwise. thank you.

If a wrong cap were used and was to high of a pressure, you could blow a hose, because of too much pressure.

If the pressure is too little than nothing will happen, other than it will release the pressure sooner than what is recommended.

May want to try bleeding the system .