SHO's temp is unstable...why?

[SHOstuff]

I just put a brand new radiator, thermostat and coolant in and with the a/c on, it runs at normal temp. But the fans are workong, I know it because I've let idle to see if it works and it does. When I'm driving on the freeway with a/c off, its ok, but it's only when driving in the city on the street that the temp raises. It doesn't overheat, just gets warmer or the temp guage raises. Could it be the radiator cap or the sensor that turns the fan on?

 

[frosho]

Sounds normal.

 

[mrecoolgar]

Does sound normal.
However there may be an air pocket in the system that needs burped out of existance.

 

[hawkeye18]

The fan turns on once the coolant reaches like 205* or something. It's controlled by the ECT sensor.

It's normal, don't worry about it.

 

[riden2low]

Did it do it before you had put the new radiator in? I replaced mine too and the temp did the same thing. But I placed a few other hoses too. I did the burp thing as most suggest but my problem was one of the hose clamps on the smaller hoses I replaced wasn't tight and was allowing air back into the system. Retighten everything and now no problem.

 

[SHOstuff]

Ok fellas...maybe it is. lol
So when cold, the radiator shows full, it still could be air in the system? Is there a purge line I could open to get the air out?

 

[chrism3784]

My temp gauge on the sho always fluctuated. Especially at a light when I accelerated a bit and stop at the next light. Would go up a little bit then shortly go back down. But I have an underdrive pulley installed that may have something to do with it.

 

[riden2low]

Ok fellas...maybe it is. lol
So when cold, the radiator shows full, it still could be air in the system? Is there a purge line I could open to get the air out?

Just undo your radiator cap a little and you will hear air going back into the over flow bottle. Just don't burn your self. The caps with the pressure relief lever on top is the easiest way, but either way, both will work

 

[frosho]

The air should be able to make it's way out of the radiator without loosening the cap. I would never loosen it while the system is pressurized. That "air" you hear going into the overflow bottle isn't air, it's steam from the water/coolant flash boiling.

While the car is idling, grab the upper rad hose and squeeze it a few times. This will help to "burp" air pockets out of the higher areas of the cooling system so that they can make their way to the radiator and out the cap.

 

[SHOstuff]

Did it do it before you had put the new radiator in? I replaced mine too and the temp did the same thing. But I placed a few other hoses too. I did the burp thing as most suggest but my problem was one of the hose clamps on the smaller hoses I replaced wasn't tight and was allowing air back into the system. Retighten everything and now no problem.

No. This didn't happen before I changed them.

 

[SHOstuff]

I will give these suggestions a try and see what happens. I will post back afterwards.

 

[hawkeye18]

Please don't open the radiator cap while the engine is warm. It is a really good way to find out what third-degree burns covering your hand and arm feel like.

did the thermostat you installed have a jiggle valve in it? If it didn't, that is what is preventing your system from properly de-airing itself. Either find a thermostat with a jiggle valve at the top of the ring, or remove the current thermostat and drill a 1/16"-1/32" hole in it at the top of the flat ring, then reinstall. That's what I did and it works wonders.

 

[ViPER1313]

grab the upper rad hose and squeeze it a few times. This will help to "burp" air pockets out of the higher areas of the cooling system so that they can make their way to the radiator and out the cap.

+1 - you can do it with the car (when it is cold) idling or off, and this will remove most of the air in the system (if the car has a stock style thermostat with a jiggle valve......)

 

[Eric VerValin]

Mine just randomly started to move around a lot more than before... usually mine dosen't get more than "level" before it goes back down, but I believe my fan kicks on a little sooner as well.

But what stopped mine from fluctuating so much was the little hose that fed the overflow bottle.. it was just loose enough to have a vac leak.. not enough to actually lose fluid, but the radiator wasn't building up pressure like it should have, and when I snugged it down, it fixed it.


Double check that something isnt loose... squeeze hoses when its off.. you should be able to hear a small leak like that...

good luck

 

[jmpSHO2nd]

I use this when burping any coolant system.

 

[SHOstuff]

I use this when burping any coolant system.

What is that and where did you get it?

 

[SHOstuff]

Ok guys...I did what y'all suggested and its now staying at the operating range that I'm use to...at least at night lol. But thank everyone of you.
But I'm curious about 2 things. With the cooling system full and clean and everything working as it should, why do some people still get a fluctuating temp besides that the car is old? And what controls the low coolant light that comes on? Mine comes on even with the system topped off.

 

[jayro]

Not 100% sure where the coolant sensor is. Im sure someone will chime in. Mine has always fluctuated in temp a little. It stays constant when driving, but at idle it will raise some until it kicks the fan on, then it cools right down. Makes since cause airflow over the radiator ect is what cools the engine. When the car is not moving with the fan off then there is no air flow.

 

[antz]

your low coolant sensor is in the overflow bottle, these cars dont like sitting around or stop and go traffic. my temp gauge wont budge past the L on normal at highway speeds, but in stop and go traffic it raises to about the R then the fan kicks on.

 

[hawkeye18]

Protip: If the needle is inbetween the hash marks, don't worry about it. Seriously, it says NORMAL for a reason.