Z3 Roadster (E36/7) Running Temp

Up until about a week ago it seems that my Temp gauge always ran right in the middle after the car warmed up. Now I just drove from the airport and noticed that the needle never went past 1/4. The heater/defrost seemed to be putting out but I'm curious why the temp doesn't hit the middle of the gauge? Is this a problem or should I just be glad my Roadster runs cool? 2001 3.0i.....

Thanks in advance to all take the time to answer.

Change your thermostat.

Originally Posted by IgotBMW

Change your thermostat.

+1

I have heard that thermostats can fail closed but I have had several fail open with the same symptom you describe except in some cases I can't even defrost the windshield.

Thanks but I'd kill that cat........

I went on some long highway drives over the past two weeks and the car started out nice and warm before I got to the highway and when I got off and got closer to home and parking the car. While on the highway the engine temp dropped to the colder side. The outside temperature was around 35 degrees.

Thermostat. I have had an identical experience in two of my old cars.

Anyone changed out the worthless (in my case) clock and put either a oil pressure guage, or a real temp. guage in its place? if so, how difficult did you find it to be?

Crappy : )

(Just outside of Nashville)

Originally Posted by crappyattitude1

Anyone changed out the worthless (in my case) clock and put either a oil pressure guage, or a real temp. guage in its place? if so, how difficult did you find it to be?

My analog clock has worked perfectly since day 1.

Originally Posted by Eighthnote

Up until about a week ago it seems that my Temp gauge always ran right in the middle after the car warmed up. Now I just drove from the airport and noticed that the needle never went past 1/4. The heater/defrost seemed to be putting out but I'm curious why the temp doesn't hit the middle of the gauge? Is this a problem or should I just be glad my Roadster runs cool? 2001 3.0i.....

As I understand it (and this has been discussed in other threads), your "temperature gauge" is really an analog warning light controlled by the car's computer. As long as the coolant temperature is in the "normal" range, the needle points to the middle. Only if the temperature is too cold or too hot outside the "normal" range will the needle deflect left of right.

You want your car to run at normal coolant temperature.

Therefore, you need to check to see if your "temperature gauge" is working properly (not sure how this is easily done; the BMW diagnostic computer?), and to double check the actual coolant temperature (external thermometer) and condition of the thermostat. Since the coolant appears to be running cold, one quick check would be to remove your thermostat and see if it is stuck open when the coolant is cold . . . or just replace it with a new, known good thermostat and see if that solves the problem.

until a few months ago... well really it still works... just doesn't keep accurate time. That and the clock on the radio and the watch on my arm both work well. I just thought that an oil pressure gauge would be mor useful. And a temprature gauge that was truly accurate would be a good thing also.....

Crappy : )

(Just outside of Nashville)

Originally Posted by BeemerMikeTX

... You want your car to run at normal coolant temperature.
Therefore, you need to check to see if your "temperature gauge" is working properly (not sure how this is easily done; the BMW diagnostic computer?), and to double check the actual coolant temperature (external thermometer) and condition of the thermostat...

I think first it would be good to know what the normal full operating temperature. It is different for each car, for instance my 2006 Scion xB is 184 and my 2008 Forester is 192, as displayed by their ScanGauges. If he thinks his cooling system has a problem, and does not previously know his full operating temperature, a temperature reading has nothing for comparison.

I do think anything between 180 and 200 is probably normal full temperature for most cars. Not to be confused with the operating range. According to their ScanGauges, the Scion's blue light goes out at 139, and the Forester's needle reaches its steady point at 155. Both the light display and the needle display are moderated to remain steady and only cause alarm if the temperature is out of the wide operating range. The term "idiot" has been applied to this feature.

A quick rough check of coolant temperature can be done with a infrared thermometer gun.
http://www.harborfreight.com/non-con...ter-96451.html
Point its laser at the tank and the hoses. The temperature displayed will probably be lower than what the ECU is sensing internally, especially since the readings are on the other side of the thermostat.

If having a BMW dealer check the actual coolant temperature costs much money, one might consider buying a ScanGauge:
http://www.amazon.com/ScanGauge-Auto...s=scangauge+ii
It shows the actual temperature sensed by the ECU, as well as about a dozen other operating parameters, plus reads codes and calculates mileage and range etc. It simply plugs into the OBD port (under the dash of most cars, or on the right side of the console in a Z3). Here's my Scion and Forester ScanGauges:
http://i49.photobucket.com/albums/f2...nGuageII_1.jpg
http://i49.photobucket.com/albums/f2...SGcoverday.jpg
I only recently got the Z3 and will give it a ScanGauge once I figure out where to put it.

Eighthnote, if the ambient outside temperature is +45F or more, you can be fooled that the heater/thermostat is still working....believe me though, when the outside temp is in the 30's, a stuck open thermostat will not keep up and you will know very quickly if you have a thermostat problem...I have had two previous Z3s that exhibited the same temp gage problem as you have and were fixed immediately by installing a new thermostat...

Originally Posted by vintage42

I think first it would be good to know what the normal full operating temperature.

Yes, you would need to know what the "normal" coolant temperature is supposed to be for your car if you are double-checking your actual coolant temperature because you don't know if the (unmarked) gauge is reading accurately. I assumed that was obvious without having to actually say it.

Originally Posted by BeemerMikeTX

Yes, you would need to know what the "normal" coolant temperature is supposed to be for your car if you are double-checking your actual coolant temperature because you don't know if the (unmarked) gauge is reading accurately. I assumed that was obvious without having to actually say it.

I apologize. It just seemed that no cars these days tell you the actual temperature, nor does a gauge that is reading correctly tell the temperature, so how would anybody know it?

Originally Posted by vintage42

I apologize. It just seemed that no cars these days tell you the actual temperature, nor does a gauge that is reading correctly tell the temperature, so how would anybody know it?

Yes, in the "old days", gauges actually told you the real-time information (coolant temp, voltage, oil temp, oil press) so it made it a little easier to trouble-shoot problems, but apparently no more. I was able to catch a failing fan belt on my 1976 VW Scirocco (in 1978) when I noticed the coolant temperature gauge was running a little bit higher than normal and the voltage gauge was running a little bit lower than normal. My 1972 Porsche 911 gauges all have numbers on them so you knew the actual temperature or pressure. By the 1980's the Porsche gauges had lost their numbers. Now gauges on cars do not even really tell you information. You have to do your own research to be able to do your own trouble-shooting.

You need a thermostat. The Gauge is a real gauge, but it's "buffered" which makes it semi-useless. If it's failing to sit at the center, the car is not reaching operating temp.

Hi Folks,

Another option for OBD gauges is the Ultra Gauge. I've been using one in my other car for a couple years and will get one for my new-to-me Z3 whenever I recover from all the unexpected expense I incurred when I bought it.

The Ultra Gauge is only about $70, but, like the ScanGauge, they are very useful and entertaining.

Cheers!

Craig

OK thanks for all the input. Now ,,,,,,,,,,,,, someone post the link to the step by step "replace the thermostat" video. And while I'm here why when I look for the replacement online I find the thermostats by themselves and I also find the thermostat in the housing for about the same coin? Both are supposed to be OEM parts. mmmmmm I think there may be rats in my chicken noodle soup..

Just ordered a new thermostat and a 32mm flat wrench (for the fan) to prepare to do this myself. The cars been sitting for a couple weeks so I thought I'd take it for a short trip around town. Of course the thermostat works fine and the car operated at normal temperature. At least I'll have what I need to fix it if it acts up again. And I'm pretty sure it will. These things often repeat themselves.