M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => General Topics => Topic started by: ClayW on May 31, 2011, 10:53:56 AM

Title: E30 Temp Gauge Range?
Post by: ClayW on May 31, 2011, 10:53:56 AM

What is the temperature range according to the E30 gauge? Can anyone accurately attach temperatures to the marks on the gauge?

Thanks in advance.

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Title: E30 Temp Gauge Range?
Post by: bmwman91 on May 31, 2011, 11:04:33 AM

Dead-center is 88-90C. The 3/4 mark is 98C (I think). It would actually be somewhat easy to figure out. If I had a spare temp sender, I could map its resistance vs. temperature & then use a potentiometer to manipulate the gauge.

Title: E30 Temp Gauge Range?
Post by: ClayW on May 31, 2011, 11:08:37 AM

Also, where does the needle sit during normal operation? Does it tend move up and down with higher ambient temperatures, spirited driving or under heavy load or is it pretty steady?

Thanks!

Title: E30 Temp Gauge Range?
Post by: bmwman91 on May 31, 2011, 12:06:53 PM

With a properly functioning thermostat (& other components), the needle should sit dead-centered on the 50% mark as seen from a normal driving position. That should not change unless you are driving really hard on a hot day (hotter), or engine-braking downhill for extended distances (colder). If the needle is reading low all the time, and driving it hard increases the temperature, your thermostat is dying. They almost always fail in an open position, running the motor too cool.

There are different thermostats available for the M42. The correct one is an 88C one. The others are of no use (unless you live in the middle of a desert maybe).

Title: E30 Temp Gauge Range?
Post by: esager on June 02, 2011, 12:19:18 AM

I replaced every darn thing in my cooling system at the same time I performed the mess under the intake delete. All quality parts from Pelican. New radiator. New fan clutch. New hoses (all of 'em). New composite water pipe. New 88C tstat. New water pump. Engine runs really well. Gage shows middle indication for 10 minutes, then creeps up to 1 or 2 needle widths above half...worst case, 1/2 way again to the 3/4 mark. Engine braking cools it down, as does opening the heater core...for a while. I don't really think anything is wrong, but I don't like the fact that I don't ride on the 1/2 mark. I think I will check my ground nut behind the cluster as the gage will very occasionally "shudder" a bit and I can tap on the gage cluster and sometimes cause the needle to move a bit...but just a bit.

Thoughts?

Title: E30 Temp Gauge Range?
Post by: bmwman91 on June 02, 2011, 12:36:22 AM

The needle should remain dead-centered under almost all driving conditions when the cooling system is operating properly.

It does sound like you have a loose connection somewhere in there.

Title: E30 Temp Gauge Range?
Post by: jrobie79 on June 03, 2011, 01:51:19 AM

check the grounding screw behind it on the cluster, might be loose, causes all sorts of craziness with the needle

edit:
didnt read the last sentence of your post....my bad