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-   -   temperature gauge needle going cold... (

noodles101 04-01-2012 08:37 PM

temperature gauge needle going cold...
i was driving on guelph line , ( the big down hill ) going 80 , down hill , no gas,

and my temperature gauge needle moved a little to the cold side till i hit a red

light and went back up to middle.

what can cause this?

edit : my coolant level is good and my radiator is half a year old.

Blackedout95 04-01-2012 08:47 PM


Is it a common issue now, go run the highway and see if at higher cooler speeds it does it again just to confirm. Sometimes it isn't enough to show its head in around town driving once the weather is warmed up a bit.

SiR 04-02-2012 10:27 AM

how much is a little?

noodles101 04-02-2012 11:09 AM


Originally Posted by SiR (Post 1557626)
how much is a little?

less then 1/8th.

usually when its holding at half its covering the half point white tick, but it went to the cold side just enough so i can see the half point white tick.

could this be because i was going down hill doing 80, for about 2 mins straight with no gas? ( this might be a really dumb guess sorry )

when i got to the bottom of the really long hill the temp went back upto half way.

drove on the highway after this happened... temp gauge needle held at half the whole ride waterloo to etobicoke.

Blackedout95 04-02-2012 02:52 PM

If you made a higher speed test run after and nothing happened (held center) then do nothing but keep your eye on it. May rear it's head again, sounds like it may be sticking open. I replaced my therm about 3 months ago because in daily driving nothing would show but as soon as I got on the highway and held 100-120 for any period on a cooler night it would suddenly drop only to go normal after slowig and in the city again. When we replaced it the ther looked fine, but it wasn't!

And no gas would not cause that. However if the operating temp of your car thinks it is too cold it could very well decide to keep adding fuel. But you should notice a bad therm far in advance of bad gas mileage.

SiR 04-03-2012 12:07 AM

I had that happen once...same conditions(less amt of time going downhill) but it was -25 out.

never happened again. it is possible this was just a fluke from the conditons. off the throttle that long downhill(At speed) CAN have the temp drop enough. my gauge gets to the middle at 77deg C..and i imagine most e36's are the same. Since you are at speed, with the rpms up(coolant being pushed by the water pump ) and being off the throttle(no combustion=less heat)...its possible.

coolant temp fluctuates and the stock gauge has a pretty big buffer/range to it. but its possible the temp went below the 77ish deg C point and caused the gauge to dip slightly.

just keep an eye on it....or if possible try to replicate it again under similar conditions.

Ive read of a few others experiencing it as well. Being that I experienced it myself and didnt see it pop up ever again makes me think its somewhat normal under those conditions.
I did change out my tstat(among other things) at a later date though just for preventative maintenance.

Mystikal 04-03-2012 11:52 AM

That's completely normal. The engine was coasting in gear generating relatively little heat (fuel and it's ignition would be at or near zero), with lots of cool air blowing through the rad and the fan clutch spinning away. There is no need for concern.

When my friends and I head south to the mountainous states there are descents that go on for miles. I can watch both my oil and water temps gradually fall as I coast down, consistently.

SiR 04-04-2012 09:50 AM


iverson03tj 04-11-2012 02:13 AM

what if my water temp stays just above the blue are while coasting on the highway? im guessing its ok right? since the engine oil temp must be at operating temp.. right?

Blackedout95 04-11-2012 06:52 AM

What do you mean coasting?

Also while you are coasting it isn;t in the winter when you need heat is it lol

SiR 04-11-2012 10:38 AM

just above the blue?

Blackedout95 04-11-2012 03:00 PM

There is no good reason for this, non, I don't care what people say, if the needle isn't centered and operating at normal temp, you have an issue.

SiR 04-11-2012 03:47 PM

depends on the severity... a minor dip (under very select circumstances )from center is possible and fine.
hovering near the blue or just above it.. not good

Blackedout95 04-11-2012 06:31 PM


Originally Posted by SiR (Post 1559506)
depends on the severity... a minor dip (under very select circumstances )from center is possible and fine.
hovering near the blue or just above it.. not good

I suppose but it would have to again be a issue which caused it, perhaps a momentary issue but an issue non the less.

No one should be comfortable driving arround under normal op temp, either a gauge, flow (hoses), therm etc issue, but an issue!

iverson03tj 04-11-2012 08:37 PM

ok cool... i bought the fan delete mod from bimmerforums... should fix it all... i also got a spal fan taht im goign to attempt to wire it into the aux fan switch... and i think the reason its soo cold is because the thermostat is stuck open ?

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