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Old 05-13-2019, 03:19 PM   #1
Join Date: Jun 2010
Location: Folsom, CA
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Running too cool

Just picked up an e30
And temp is getting to a little past a quarter way.
Is this too cool?
Is the gauge not reading correctly?
It was 80 degrees outside when I was driving it.
My other e30 I was trying to keep temps below half way and this car I can not get to half way mark on the temp gauge?
I donít want any overheating issues

Last edited by steelynorm; 05-13-2019 at 05:07 PM.
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Old 05-13-2019, 03:59 PM   #2
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Thatís where mine is at after a fresh water pump and thermostat and fan clutch.

Before it stayed rock solid in the middle.
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Old 05-13-2019, 08:21 PM   #3
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I would first get an idea of where the car is running by using an infrared thermometer on the hoses in various places. Also, I would make sure the system is holding the correct pressure. In addition, be aware that thermostats vary between manufacturers.

Keep in mind that it is very important not to overheat a new thermostat dry. Bring the coolant up to full gradually. I usually fill my system from loosened hoses - fill the block and heater through a heater hose, then I pull the top radiator hose at the stat housing and fill the radiator. Rarely need to bleed too much using this method.

Its also possible to experiment with warmer stats. from the E36. I sometimes run 88 degree stats in the winter here in Maine. Stat performance varies by brand as I said earlier.

Contrary to popular belief, it is important to get your car to operate at the proper temperature ASAP. Rich cold starts and running = BAD!
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Old 05-15-2019, 12:39 PM   #4
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I bet either the thermostat is stuck open (or missing) or the gauge is wrong.
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Old 05-15-2019, 04:09 PM   #5
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After a complete cooling system overhaul and refurbishing my instrument cluster, my needle also goes in the quarter mark area. Only in summer California sun, bumper to bumper traffic, does my needle hit half way.
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Old 05-15-2019, 04:20 PM   #6
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In my experience the oem temp gauge has a it of a mind of its own. To put your mind at ease, take the thermostat out and put it in a pot of boiling hot water and see if it opens completely. if it does then you can assume it is working properly. Also make a note of the temperature on the thermostat. should be somewhere between 80 and 90 degrees.

What you describe is about where mine sits, and the VDO temp gauge i have reads about 85 which is what my particular thermostat is. But then some people report that it sits at half way when normal, so i dunno. you just need to figure out what is "normal" when you have proved the cooling system is in working order. then monitor it from there.
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Old 05-15-2019, 04:45 PM   #7
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Mine is at a quarter with a new radiator, thermostat, water pump, and new blue and brown plug ins

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Old 05-15-2019, 06:17 PM   #8
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Don't forget that there are 2 OEM thermostats, a 70C and 80C. In my experience (Southeastern PA), I've always found 70C to run too cold. Plenty of valid advice in the comments above, could also just be 70C thermostat and a change to 80C will get it up closer to the halfway mark. Anything past the 1/4 mark should be fine. Colder than that isn't ideal for efficiency or wear in general.


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Old 05-16-2019, 06:16 AM   #9
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In the winter time, it takes my car 20 min to get the needle past the 1/4 mark. In the summer, the needle always sits at 1/2.
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Old 05-16-2019, 09:38 AM   #10
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maybe try getting an actual gauge in there and see where it actually runs. I have a similar issue on my car where itll drop into the 170s cruising and my standalone will go back into warmup mode and it kills my gas mileage. im personally trying a higher temp tstat soon to try and remedy the issue. not sure if that will have a huge effect on an m20 though

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Old 05-16-2019, 12:31 PM   #11
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To be clear: Do not drop your thermostat in a pan of boiling water. The shock will ruin the thermostat. It is important to bring it slowly to a hot temperature.
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