Alright, a simple question,

If the car starts to overheat, will the overflow tank be spewing out coolant?

I ask this because, I have had a motor rebuild and the like, and im having to get a chip put in because of the new cam.

Anyway, my temp guage likes to get up to 235+ after a while of driving, and today when I shut my car off, the temp rose to 260 on the dot, which is in the red on my GTA's digital dash.

I got out, opened the hood, and made sure nothing was spewing, the overflow tank was right at the FULL HOT line.

Could the dash be off also?

 

I would assume that if there is too much liquid in the system, ie the overflow tank is completely full on a cold car, that it would spew when overheated, as everything expands with heat. The overflow tank would get full and overrun if it was completely full when cold.

 

Im talking about when the car is full blown overheating, if it should be spewing or not.

There's the right amount of coolant in the car

 

yes and no

the cap will let fluid release happen when it reaches more than what it is rated, 15 or 16 PSI

and this only usually happens when its too hot

so thats why the answer is yes and no both

you need to fix what is causing the overheating

before you end up with a blow gasket and/or blown engine, if there isnt damage already

but you already know this


the right amount of coolant will cause about an inch and half or so of air space at the top of the radiator when its cold

this is due to expansion when fluids cool

although this is only going to occur if you have no coolant recovery tank

if you do have a tank and its working properly then it will have no air space when fully cooled, such is the case in the vehicles in years before such tanks were used,

on some of my vehicles i remove the tank and jut run the release hose along the radiator hanging towards the ground, like they used to back in the olden days

if it never overheats severely then it will always be full when at operating temp and be just about an inch and a half of air at top of radiator when cold, nothing out of the ordinary



good luck

 

If your engine was at 235+ while you were driving it around, it probably already did all the spewing it was going to. You were probably low on coolant by the time you pegged the gauge, and hopefully that's why it got so hot.

Then again... I would expect to see a party going on in the overflow tank if your motor topped 260. Gauge could be wrong. You just dropped a lot of money in your motor to be trusting the stock temp gauge, and a digital one at that. I would suggest getting a mechanical one. My stock gauge is all over the place even with a new sender, and I do not trust it at all.

I hope you figure this out, and I hope your gauge is wrong, 'cause I would not want to be driving it at 235.

Edit: If you don't want to add an aftermarket gauge just yet, first try replacing the sender for your temp gauge. It's cheap and could be all that's wrong. Autozone calls this a "temperature switch," not to be confused with the "coolant temperature sensor" which has nothing to do with your gauge. The part you want to replace is in the driver's side head below the manifold and has one green wire attached to it.

 

Im not talking about the Radiator Cap itself, but the plastic overflow bottle.

Everytime the car has gotten up over 235+ the overflow tank has never been above the FULL HOT line, even when it pegged at 260 with car off this afternoon, so im thinking maybe the stock guage could be off.

 

he obviously didnt read our replies very well, answers are all in them

the cap is a very important and functional part of the cooling system, if its not working right then problems will occur, and yes it has to do with overheating and the coolant tank and so forth, directly


this isnt rocket science here, its very basic, the cap ids what allows the fluid ot spew out of the radiator and into the tank, simple as that

the temp of the fluid in the block where the temp sender is at probably increases in temp as the car sits not running after just being run hot because it is sitting in the block in which is the hottest place in the car and therefore cooks the fluid up to as hot as the engine is,
so it is very possible that the engine is still getting too hot, but then it is also possible that the guage could be reading higher than it should, especially if it is the original guage, these guages are known for not lasting forever and being innacurate and have a tendancy to read higher than actual

but it is still fishy to see that it reads higher when after it has been sitting not running for a bit



good luck though

 

Not fishy at all. You said it yourself - When the engine gets shut off, the temperature will actually continue to go up for a while, because the water pump isn't moving anymore.

 

Is the lower air dam installed on your car? If not, your radiator will not get enough air to cool the coolant. Are your cooling fans turning on when they are supposed to? THat is the problem we are having with my wife's GTA...

 

Yes, the air dam is installed on the car.

My driver side fan spins all the time, whenever the car is on, it's on.

My passenger side fan is NOT coming on for some reason, (which is wierd because before the rebuild, it came on when needed and the car never got too hot)

Also, before the rebuild, the car had a 195 degree T-Stat in the car, and now the car has a new 180 degree T-Stat.

 

You can test the thermostat by putting it in a pan with hot water and heat that up on a stove and see if the thermostat changes when you hit 180 degrees.

Measure the resistance of the temp sensor to make sure its in range. If you search on here, should be able to find a resistance table.

You did take the radiator cap off and check to make sure there is coolant in the radiator, right? If there isn't, check for leaks or replace the radiator cap.

I'm leaning towards a bad temp sensor because the 2nd fan never kicks on. Then again, there might be a bad connection/wire going to the 2nd fan.

Could have something blocking the radiator too, maybe try flushing it, if you don't find anything.