: Temp gauge reading high, engine not hot.


VegasBrad
11-27-2010, 03:35 PM
If this has already been addressed I haven't been able to find it.
06 M6, headers, cam etc, 160 degree thermostat. The other day during normal driving my temp gauge read that the car was over heating. This is odd because the car runs solid all summer here in Las Vegas, even while sitting in traffic when it's 120 outside. My first thought with cooling issues is always the thermostat, I took it out and tested it and didn't see it open. Hooked the hose back up without the t stat and went for a spin. By the time I got back home the gauge was reading near danger levels, but when I opened the hood the engine did not appear to be NEARLY as hot as the gauge indicated. Faulty engine temp sensor? Short in the system? Any help is greatly appreciated!

ericsgixxer1000
11-27-2010, 04:27 PM
bad water pump

rextheracer
11-27-2010, 05:53 PM
bad radiator cap....replace it....fixed.

gotzaGTO
11-27-2010, 10:06 PM
Another possibility too is that there have been those of us with electrical gremlins in our clusters and the coolant needle spikes to looking like its over heating when the car is not. That's if you're talking about the stock gauge. Also too, if were talking about the stock gauge, its a dummy gauge meaning that once the car gets to operating temps, it stops moving until the car over heats and then it will spike.

Lonestar
11-27-2010, 10:13 PM
there could also be an air bubble in the system. pull the radiator cap off, and let the car get to operating temperature. once its warmed up and the thermostat has opened, fill the radiator up to the top and put the cap back on. drive it around and see if it still does it


if the radiator cap was bad, you would be hearing it boil while the temp guage is pegged. if that isnt the case, it can also be the water pump like someone else said.
good luck

mistermike
11-28-2010, 04:52 AM
Massive thread-o-fail.

Poor description of a problem answered by people saying what ever pops into their heads.

It has not even been determined if the actual temperatures were normal or abnormal.

Oh4GTO
11-28-2010, 10:10 AM
This thread is def full of stupid answers. Especially the water pump. When you shut the car off and then restart what does it read?

Shocker
11-28-2010, 10:20 AM
Another possibility too is that there have been those of us with electrical gremlins in our clusters and the coolant needle spikes to looking like its over heating when the car is not. That's if you're talking about the stock gauge. Also too, if were talking about the stock gauge, its a dummy gauge meaning that once the car gets to operating temps, it stops moving until the car over heats and then it will spike.

Yea, I get this every once in awhile!

VegasBrad
11-28-2010, 11:21 AM
The engine is definitely not overheating as the gauge indicates. Last night on a wing and a prayer I replaced the engine temp sensor because it was cheap and easy, then let the car run with the rad cap off, once the fluid got to the point of almost spilling out I replaced the cap. The temp gauge was reading normal and I thought I was in the clear but right before I declared victory it started to rise again. Took the car for another spin around the block and again when I returned the temp gauge was pegged, when I popped the hood there were no symptoms of overheating. Though the fan did run for a few minutes after I turned the car off. I let it sit for maybe an hour then took it out again, temp gauge again pegged right away and I turned the heater on out of curiosity. No hot air.

VegasBrad
11-28-2010, 11:24 AM
Also, it sounds like no matter what my problem is this time it would be a good idea to get an aftermarket temp gauge. Any suggestions?

Oh4GTO
11-28-2010, 11:40 AM
I just dealt with the same issue. It took me a year to figure it out. The connection on the male plug for the temp sensor was bad. The car would show hot but it wasn't. I would shut it down then immediately restart and the gauge would return back to cold and slowly begin it's rise. I then unplugged it and it did the same. That's what caused me to believe it was electrical since everything else under the hood was replaced.

mistermike
11-28-2010, 12:13 PM
The engine is definitely not overheating as the gauge indicates. Last night on a wing and a prayer I replaced the engine temp sensor because it was cheap and easy, then let the car run with the rad cap off, once the fluid got to the point of almost spilling out I replaced the cap. The temp gauge was reading normal and I thought I was in the clear but right before I declared victory it started to rise again. Took the car for another spin around the block and again when I returned the temp gauge was pegged, when I popped the hood there were no symptoms of overheating. Though the fan did run for a few minutes after I turned the car off. I let it sit for maybe an hour then took it out again, temp gauge again pegged right away and I turned the heater on out of curiosity. No hot air.

No heater usually means bad water pump if the coolant level is adequate. Thermostat is outside the heater loop. A failed water pump will go from ice cold to overheat very quickly.