Car Over heating even though the theromostat is not in it

So my car started overheating suddenly out of the blue…Every other vehicle that I have owned the overheating was caused by a stuck thermostat so I removed that and plan to get a new one on my next paycheck.

This only served to extend the time it takes for the car to overheat.

I drive multiple times a day about 12 miles one way…first part of my trip is highway at 60mph then a bridge and city (Lots of stoplights ) 45mph and then highway and a large bridge at 75mph. Like clockwork at the second light into the city driving my car goes from normal temps to about half just while waiting for the light. When I start driving after the needle moves at a steady pace toward the red and hovers just off of it for id say 2 min or so and then it just pegs quickly right to the end of the gauge.

Like I said I already tried the thermostat and that didn’t work.

There are 2 fans attached to the radiator…nither of them come on when the AC is turned on though both of them spin when the engine is overheating. One of the fans also has a loud clicking sound and dose not blow even half the air as the other. Could this be my whole problem ?

I noticed just recently as well while I was filling the coolant to make sure it was full at the radiator that the liquid was bubbling…it was not boiling it was just bubbling away.

also when the car is hot the heater runs cold.

I have also sprayed off the front of the radiator with a hose because I know that was a buddies problem once.

What dose this sound like to you guys? Any help would be great.

its rough to say what your original problem was. Though at this point it seems that the cooling system just has air in it. air in it will cause it to overheat, bubble, and the heater to blow cold. you need to fill your coolant completely up with the car cold, preferably with the front of the car lifted up to force the coolant to fill the system. I would also install your new thermostat befre doing this stuff.

Both of your cooling fans should be on when the AC is used. The fans should also run smoothly and quietly. In addition…one of the jobs of the thermostat is to slow down the coolant flow through the radiatorso that it has time to cool down. You have multiple cooling system problems that can be easily corrected by a visit to a good independent mechanic. Get a new thermostat and make sure it’s properly installed before you take your vehicle to the mechanic. That will be one less problem area for him to deal with.

Be sure your coolant is circulating. The impeller on the waterpump shaft can sometimes break free from the shaft. When that happens, your coolant circulation stops, triggering overheating.

You have a job? You can’t afford a $15 thermostat? Apply for a credit card. Put the thermostat on the card. Pay the credit card balance next month. A credit card if for emergency purchases. Do not use it for buying a case of beer or a plasma tv.

Are you loosing coolant? If so. my first though is intake manifold gasket if you have a V6 engine. Otherwise water pump if your lucky, headgasket if your not. If you are very lucky, it might just be a defective overflow cap, but its not looking like this could be the case.

You need to address the thermostat issue and the fan problem. BTW, I don’t think there was anything wrong with your thermostat in the first place.

As mentioned, the various causes could be a defective water pump, cooling fans no working, a plugged radiator, or leaking head gasket. Some detailed testing is in order here to get at the actual cause.

A faulty radiator cap that keeps the system from pressurizing could cause localized boiling.
The resulting steam bubbles could give the same symptom as air in the system.
The radiator hoses should feel more firm when its warmed up.

One way to check for a blown head gasket is to watch the coolant in the radiator as the engine is running. If bubbles form in the coolant there’s a head gasket leak.


Well I just noticed something when someone took my car to the store (They didnt know it was overheating) When they got back they said it had overheated but…I checked agian…The large tube between the thermostat and the radiator on the driver side was hot…the hose between the radiator and the waterpump on the passgenger side was cold…Dose that mean my problem is my waterpump?

It could be a clogged radiator, preventing flow through it. That way, the hot coolant cannot cool. Any radiator shop can flow-test a radiator for you. Or, you could run a hose through the upper connection and see if it flows out of yhe bottom connection as fast as it goes in.

Here’s something to consider . . .

If the radiator is clogged, it could be because of a blown headgasket

If the headgasket is blown, oil and coolant will mix, and the stuff flowing through the coolant system will be like a chocolate milkshake. And the radiator may very well become plugged

Seen it a few times

well i tested both radiator hoses by pulling the off and starting the car no odd colors no obvious flow problems

With everything you describe, the engine has a blown head gasket.

Plain and simple.


Completely removing the thermostat may actually cause an otherwise normally working engine to overheat. It depends on the cooling system design. The thermostat is supposed to divide what amount of coolant goes through the radiator and what amount goes through the engine in order to achieve the perfect operating temperature. What can happen is without a thermostat in the loop, too much coolant goes through the radiator, and not enough of flows through the engine. So while there could be multiple other issues here, it is going to be hard to diagnose until a working thermostat is re-installed.

You could have so much air in the system from a leak or bad head gasket that your water pump has no coolant to pump.

The bottom line here is that the entire system needs to be gone over.
The radiator for flow and even heat dissipation,
the radiator cap for proper release of eth pressurized fluid,
the pump for flow and leakage,
the fans and their associated relays for operation,
the cooling system as a whole and/or the cylinders for evidence of a headgasket leak,
and… last but not least… the intake manifold gaskets.
Only after you know the full extent of the problems will you be able to intelligently assess what needs to be done.

I suspect that by not properly addressing a problem as soon as you discovered you had one, and by not properly monitoring coolant levels, you’ve allowed the original problem to manifest itself as secondary and tertiary problems that have caused the ultimate repair cost to skyrocket. I suspect you have multiple problems now.

I hope I’m wrong.

I just went through this on my 1950 cad. The radiator needed to be rodded out (it was plugged up with junk). Running a car with no thermostat on the highway WILL cause overheating. Coolant flows too quickly to be cooled down in the rad before its recirculated.

If it was my car Id go to napa, get the highest priced, best quality thermo available for my car. Flush your system, and install the new thermostat. Run the car. Put your hand on various parts of the thermostat. It should all be very hot to the touch. If any areas are noticeably cooler (once the car is fully warmed up mind you) then your radiator is clogged and needs to be rodded out. Depending on year make and model it might be cheaper to just replace or recore the radiator.

I had to knock out freeze plugs and clean out the block too but thats on a really old neglected car. After all that mine still indicated overheating but its a bad temp sensor bc a meat thermometer concluded it was cool as a cucumber.

You can buy test kits that test for exhaust gasses in the coolant indicating a blown head gasket.

Good luck. One thing at a time.

Sounds like a blown head gasket. Cars made in the last 25-30 years aren’t designed to run without a t-stat. Running an engine without one can and will lead to overheating. as many times as your engine has overheated I would have to believe there’s a head gasket blown.

If the car has a 3.4L engine the thermostat is a bypass type and the engine will overheat with the thermostat removed.

And let me be clear, operating an engine that uses a bypass thermostat without a proper thermostat will CAUSE the engine to overheat.