My car was over heating and found out that the tstat was locked so I pulled out the tstat. since I didn't have a replacement I didn't put one in. The car started running fine. But after few months it has started overheating again and has been disposing coolant through the overflow. so I have had to fill in quite a bit.

I was wondering if its due to the missing thermostat but its hard to believe since it ran fine for a few months. I have checked for debris between the gap of the radiator and condensor.

Any thoughts?>??

Thanks

 

You are setting yourself up for some major engine damage, i.e.cracked heads. The purpose of the stat is to regulate the flow of coolant through the engine at approximately 195°F so the coolant can absorb the motor's heat. This in turn allows the coolant in the radiator to loose the heat it absorbed from the motor. If you remove the stat, the coolant will do the job OK on short trips but on long runs the coolant will not have enough time to give up the heat through the radiator and it will overheat. Get a new stat put in ASAP!

Ed

 

sounds like it already pushed a headgasket or cracked a head.cylinder pressure is what causing the jug to spit out.

 

 

Actualy the Tstat is there to get the motor to the proper opperating temp faster in the summer and to get to the proper opperating temp and keep it there in the cold. A cold engine will not opperate as efficiently as an engine running at the proper temp. Removing the Tstat would definetly not cause the motor to get hot, just the opposite. You give very little info but depending on milage and past maintanance there are a number of things that could be causing overheating. You could have a bad water pump, your fans may not be comming on, a clogged radiator, a bad head gasket, a cracked block or head, your running too lean....without knowing the miles, the condition of your car or the mods that you have done, it could be any of the above. Find the cause of the overheating and fix that first then put the Tstat back in to run at proper opp temp. Starting with the easiest fist, assuming you have no check engine light which means your not running lean, check the fans, if they are ok, you have to start taking stuff apart. I would check the radiator next, then replace the water pump. After that your into major engine tear down.

 

ZO6 Rules........I agree with dpd. First, put the stat back in. To check if you have cracked something remove the coolant tank cap WITH A COLD ENGINE. Start the motor and watch for air bubbles in the coolant tank as the motor warms to operating temperature. If you get bubbles, find someone to replace the HGs and the heads. If no bubbles, hope for the best.

ED

 

Again with the limited info we have, the spitting could be from overheating. If it happens cold then I agree that there is a bad gasket or crack.

 

Contrary to popular belief, running with no thermostat can cause overheating. When the thermostat is closed, the flow of water is stopped at the exit end. The resulting pressure from the water pump fills all voids in the engine with cooling water. Without this pressure, there are parts of the engine, usually in the heads, that end up with dry air pockets. This results in overheating of all metal parts not in contact with coolant. Always run with a thermostat installed.

 

Thank you all for the suggestions. Seems like I need to put the tstat back on to start finding out what is wrong. Eventhough after taking the tstat out during this summer the car ran fine for 6 months.

For the mods: I just put the LT headers on and have not gotten a tune yet. I do have the check engine light on but that came after I installed the headers for the lack of rear 02 sensors. But amazingly the car over heating started again after the install may be its just a conincidence.

The car has 63000 miles so far. It only over heats during slow driving I just did a 250 miles trip last weekend and the temperature never went above 173.

I hope this gives some more info.

Thanks

 

Sounds more and more like the fans are not comming on. you say that at speed you do not over heat. That is because at speed air is being forced through the radiator, when you stop if the fans don't come on you get hot very fast. You may have accidently disconected the temp relay to the fans when you put the headers in. Start the car and let it warm up with the hood open and watch the fans. The main fan should come on at 215 degrees. The secondary fan should come on when you turn on the AC. When the fans come on you will see the temp drop very quickly. If they don't come on you will over heat. You also need to do something about the oxygen sensors. They are an important part of the engine control system. Without them you may be running rich or lean and the computer will not know. If you run too lean you could fry the motor as someone who posted recently that this happened to him when a tune he had done set the mixture too lean.

PS: the 173 temp at speed is low and due to not having the Tstat in. You should be running around 190 to 215.

 

Very well put there. It is a flow control device without it the coolant flows to fast through the radiator and does not lose much heat.

 

The modern preasurized cooling system is preasurized by the radiator cap not the thermostat. The proper operation of the cooling system is: Coolant fills the engine, radiator, heater core and hoses. The highest point of the cooling system is the radiator cap. The radiator cap has a spring loaded seal which sets the preasure in the system by opening at a certain preasure and maintaining a seal below that preasure. The cap also allows for coolant flow into the radiator at any negative preasure. The thermostat sits between two circuits of coolant flow. The main circuit is the water pump pumping water around the engine. The second circuit is the radiator flow. When the engine reaches the high operating temperature the thermostat opens, causing coolant to now flow through both the engine and the radiator. The radiator now takes the excess heat and radiates it into the air, lowering the temperature of the coolant returning to the engine. When the temp reaches the low opperating temp, the thermostat closes, circulating coolant only through the engine again.
As the water temp goes up it expands causing preasure to build up. When the preasure exceeds the cap setting, water (and any air that has entered the system which settles at the high point, which is where the radiator cap is located) flows into the overflow tank. As the system cools off, the coolant volume shrinks and the deficite is sucked into the system from the overflow tank. If the thermostat is removed, coolant always flows through the radiator and engine which removes too much heat and causes the engine to run at too low an opperating temp.
One added system in corvettes and other newer vehicle is the addition of temperature controled fans. These fans only come on at a temperature slightly above the high opperating temp and pull air through the radiator. These fans are usualy only needed when the car is stopped or going too slow to effectively transfer the heat from the radiator to the air. Most likely due to the fact that the car runs cool at speed but overheats when in traffic, the fans are not comming on and causing the problem.

 

Sounds to me as if the lower front end should be checked... I'm betting youve got "crud" on the radiator. When at speed, the radiator is basically force cooled. At a MUCH higher CFM then the fans could ever hope to achieve. And or the fans may not be kicking on.

And get that T-Stat back in there.

 

You could probably run your car without changing the oil for several years and not have a problem. That doesn't mean that you're not damaging things as you do it. I hope it's nothing serious

 

Hey Z06rules:
What was the final solution. I am very curious.