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

DISCUSSION => Engine + Driveline => Topic started by: H8Rain on May 23, 2011, 05:23:49 PM

Title: Temp Gauge reading Colder than normal?
Post by: H8Rain on May 23, 2011, 05:23:49 PM

So here's the deal.  Took a 200 mile trip.  During the entire trip, as I cruised at around 70mph the temp gauge read slightly colder than normal (needle was at about 10 o-clock).  When I would get stuck in some traffic and idle or drive about 10mph the temp gauge would go up to normal (needle at 12-noon).

I'm used to overheating issues, but this ones got me confussed?

Any suggestions?

Title: Temp Gauge reading Colder than normal?
Post by: MikeDE on May 23, 2011, 05:33:21 PM

Most likely t-stat is getting sticky, I have had some also that have stuck open.  My E36 M3 would barely get above 1/4 when this happened.  I just swapped one on an E46 323i that was stuck open.  And my 318i(M40) was like that when I bought it.

Title: Temp Gauge reading Colder than normal?
Post by: monty23psk on May 23, 2011, 10:57:09 PM

Seems normal with a lot of air hitting your engine constantly. Mine does this and has new tstat and temp coolant sender.

Title: Temp Gauge reading Colder than normal?
Post by: DesktopDave on May 24, 2011, 07:11:05 AM

How long does it take to heat up?  That'd be the easy way to check the thermostat.  You could also do a temperature resistance test on the sensor...those don't last forever.

Title: Temp Gauge reading Colder than normal?
Post by: bmwman91 on May 24, 2011, 12:55:15 PM

It is most likely the thermostat. They usually fail open & run the motor cold (which is better than the alternative).

If you do replace it, make sure to use the 88C one, not the 80C one.