Overheating question

Derek · Jan 17, 2010

A few weeks ago my temp gauge started acting wild and I noticed the usual puddles of coolant and other symptoms of a leak. Simple enough but after tracking it down to a hole in my radiator and replacing that today, I drove it to see if it was resolved and i'm getting the same wackiness from the temp gauge...

once I start driving the car (at highway speed), the temp gauge makes a full sweep from the N all the way to the L, sits there for a second and then goes back down in between N and O. When I got back home today I let it idle for a minute just to see what'll happen and it started creeping up slowly until it reached M. After getting an instant headache because of this, I decided to just eat a payday and try again tomorrow :dontknow:

What am I not thinking of due to frustration? All other parts have been checked and with the new radiator, the cooling system should be 100%....any ideas?

ivan12 · Jan 17, 2010

I would either replace the temp sending sensor (driver's side on lower intake man) or install an aftermarket gauge. I was having some overheating issues and replaced my rad with a mishimoto. The car drives good but once in a while it will go all the way to the redline. Good luck and keep me posted, hopefuly you'll find the problem before I do

Lebedin8654 · Jan 17, 2010

it could be the thermostat hanging up

reduceallpain · Jan 17, 2010

Just your radiator caps to a 13psi one.......... Bet you thats the problem.. Had the same problem with my car..

Javi · Jan 17, 2010

change the radiator cap, check the thermostat and get a mechanical temperature gauge installed
the factory gauges suck..

ivan12 · Jan 18, 2010

How do you know when your thermostat is bad? Is it only when it gets stuck or are there any other symptoms?

vermilion · Jan 18, 2010

on my 4.6 the coolant rushed out of the cap. i didnt have any overheating. changed t-stat and switched from water to anti-freeze.

CC'S95GT · Jan 18, 2010

Did your fan ever kick on when it was idling in your driveway?
The fans are controled by a different sensor that the guage is.
There is no other way to tell if the thermostat is fubar than when it starts acting up.
You might still have air in the system from when you replaced the rad

Derek · Jan 18, 2010

The thermostat and cap were changed out (OEM replacements) when I first started having problems so they're maybe a week and a half old. I thought it was the CCRM not turning on the fans but it's ok so I'll air it out and yes, I will DEFINITELY be buying an aftermarket gauge

x182dan · Jan 18, 2010

You could have an air pocket in the system where the temp gauge is at which would cause unusual readings. The factory gauge does suck for accuracy but it shouldn't jump around like that.

Derek · Jan 18, 2010

Alrite, so I "burped" the car and took it for a spin right after and....The same full sweep after getting up to highway speed!this time though, it went back to it's usual N-O area and stayed there even after I got home and let it idle

It's gotta be a gauge issue but I still worry.....

2slo95fiveoh · Jan 18, 2010

If the gauge sending unit was functioning properly, the only (common) cause of the erratic needle movement would be the sending unit
trying to read a hot air pocket in the cooling system, so if you let the system burp long enough to get to operational temp and the
thermostat to open, then your sending unit/gauge is more than likely effed up. My autometer gauge in my car can stay at 190, and
the factory one will travel from "N" to "M" randomly.. Autometer FTW.

red95r · Jan 18, 2010

yeah i had a similar problem after putting a new thermo in. it would sweep up and down after some highway driving. it was reading air pockets that were in it and so i burped it and it seemed to happen less often. now i don't even have a problem with it flying anymore.

Derek · Jan 18, 2010

Cool, yeah after burping it today it did fine after one sweep so i'll keep an eye on it BUT I still want another gauge lol

Derek · Jan 20, 2010

Welp....while I was on my way to work yersterday, the temp gauge went all the way up to "L" and stayed there. After screaming "WTF" at the top of my lungs, I threw the car over to the shoulder and popped the hood. NOW MY BOTTOM HOSE IS PISSING COOLANT!

Now I know for a fact that I checked both hoses before I bought the radiator to see if I needed new hoses as well. I guess the radiator is too new and making other parts jealous but this is terrible and to make it even worse, I had to slide over to let a DAEWOO pass me on the way home (2 lane country road).

ivan12 · Jan 20, 2010

Daewoo really? Hahaha. Replace the hose, and invest in an aftermarket gauge. It's a good investment and a good tool
to diagnose your heating problems. If I were you and had the extra cash I would swap out all the hoses including the bypass. Burp it again and make sure you have a good mix if coolant and distilled water. My .02

CC'S95GT · Jan 20, 2010

fyi the heater core can also help bail you out if the temp gets to high again. Just turn the heat in the car on hi and fan on hi. You might need to roll down the windows after a few minutes though.

2slo95fiveoh · Jan 20, 2010

DESERTCOX05 said:
fyi the heater core can also help bail you out if the temp gets to high again. Just turn the heat in the car on hi and fan on hi. You might need to roll down the windows after a few minutes though.

Good call. And that reminds me "Derek", did you have the heater on high when you burped the cooling system previously?
Since you have to replace the lower Rad hose, I would suggest replacing both at the same time, and get some new
hose clamps (the "worm" style you tighten with a 8mm socket, or flathead screwdriver).. Then burp the cooling system with the heater on high,
and you should be good to go until you get an autometer gauge.

Derek · Jan 21, 2010

Yeah, I had the heat up to the max when I burped it the first time and when I had my run in with the Daewoo that night...I've had to use that trick before way back in the day

All hoses/clamps were replaced and I don't think I burped the car long enough the first time to get ALL of the air out so, after I changed out the hoses, I burped again (I had more time this time), had a nice convo with my car about the weather and everything is fine now. Problem solved