Temp gauge - where's it supposed to be?

[monkeyodeath]

Sorry if this is a really dumb question, but I'm new to these cars and I'm trying to evaluate to condition of the one I just bought.

Where's the temp. gauge supposed to be during normal driving? How high on the gauge is "too high"?

I just bought a 325i and during freeway driving, the needle stays a little bit (like 2-3 hash marks) below halfway. Driving up the canyon to my house, working the engine a bit more, it went up to maybe 2 hash marks above halfway.

Sorry if this is a stupid question...just trying to get an idea of what to look for and if I need to go through and check the cooling system (PO was into e30's and said everything was fine, but I'd rather be safe than shopping for a new cylinder head.)

[bmw325csi]

anywhere, depending on your thermostat setup and local weather, just as long as its not in the blue (car wont drive right) or in the red, your ok.

[Sagaris]

It should be very close to 1/2 on the gauge, a needle thickness below when cruising, and a needle thickness above while idling or driving hard.

FYI: If you change your thermostat to a lower temp. thermostat to make it run cooler, then you are retarded/misinformed. The hotter an engine runs, the more efficient it is, however there are limitations to what the oil and metal in the engine can handle. If you have cooling problems then something in the system is amiss. When people purposely run a lower temp. thermostat which causes their car to run at 1/3 on the temp gauge (and lower) the oil does not evaporate accumulated moisture as well, combustion is not as complete which causes carbon buildup, and the oil is not allowed to reach normal temperatures. You get decreased performance, carbon buildup, and shorter engine life.

[Rau]

It should be very close to 1/2 on the gauge, a needle thickness below when cruising, and a needle thickness above while idling or driving hard.

FYI: If you change your thermostat to a lower temp. thermostat to make it run cooler, then you are retarded/misinformed. The hotter an engine runs, the more efficient it is, however there are limitations to what the oil and metal in the engine can handle. If you have cooling problems then something in the system is amiss. When people purposely run a lower temp. thermostat which causes their car to run at 1/3 on the temp gauge (and lower) the oil does not evaporate accumulated moisture as well, combustion is not as complete which causes carbon buildup, and the oil is not allowed to reach normal temperatures. You get decreased performance, carbon buildup, and shorter engine life.

bought my 325e a few months ago and it always runs low, like 1/3 or less. unless im sitting idle in traffic, then it stays around the halfway mark. looks like I need to change my thermostat then.....

[CarsSuck]

I run a standard 80* thermostat in my 325is and i generally run between the first quarter mark and the half mark. Doesn't go past half unless i have a/c on in summer. Its the same in hot and cold weather, and it has been this way since i bought it.

[Sagaris]

I have replaced 3 stuck thermostats (Camry, 1991 325i, 1998 Jetta) and 1 wrong temp. thermostat (1990 325i) in the last few years.I can't believe how common of a problem stuck thermostats are. Luckily all mine have been stuck open rather than stuck closed. I removed the the A/C condenser and aux. fan on my 1991 325i in May 2010, and the temperature was perfect over the summer but it tends to run ~2 needle thicknesses below 1/2 when its cooler than ~55F outside. I wish the gauge would read right in the center year round but the extra airflow makes it overcool just a tad. I dont drive the car in the winter though so it isnt much of an issue. Just a consideration for a lower than anticipated gauge reading on an otherwise refreshed cooling system

[BergerNJ]

so my new 325 verts needle will bounc a bit soemtimes....and I've had to already tap the dash to make it work.

Should I consider replacing the dash?

some of the lights don't work in the extreme cold.

[jlevie]

With a stock 80c thermostat in the car, the needle should rest halfway between the 1/4 & 1/2 marks when driven at speeds 45mph or above. It may rise to a needle's width above 1/2 with the A/C when idling or in stop and go traffic.

A bouncing or erratic temp gauge is usually caused by a bad connection where the gauge bolts to the PCB in the cluster. Re-flowing solder on the pads for the temp and fuel gauge is the best fix.