m20b20 low working temperature?

[Brdjo]

As wither days comes I noticed that my e30 only stuck in traffic comes to middle point on temp gauge.. On open road no matter how long the drive is, gauge sits on first white mark..

pic:https://ibb.co/hXdYUb

I did read on e30wiki that this is not so alarming but my heating is not so great as it should be..

Is this indication of thermostat failure, not closing all the way or could be something else?

[paultv]

You probably have an 80c stat which is usual I think and a quarter reading whilst driving is normal and so is middle reading standing in traffic, any higher you may have a problem.

I find the hot air supply a bit feeble in the winter here, but better than a head warp!

Paul

[paultv]

You probably have an 80c stat which is usual I think and a quarter reading whilst driving is normal and so is middle reading standing in traffic, any higher you may have a problem.

I find the hot air supply a bit feeble in the winter here, but better than a head warp!

Paul

[Brianmoooore]

Thermostat is the only possible reason for an engine running too cool, but, looking at your pic., that point on the gauge corresponds to about 80 degrees, which is correct for an M20.
OE BMW thermostats are notorious for one side of the 'bridge piece' breaking, letting the valve of the 'stat sit at a slight angle and not close properly, but if your gauge never goes lower than in the pic., when moving at speed but with the engine lightly loaded, then I doubt if there's a problem at all.
Poor heater could be a partly clogged matrix or valve, or even a problem with the heat control Bowden cables, not fully shutting off the cold air.

[Brdjo]

Thanks for help..

It never goes below first white, no matter what. I test this while driving 6km downhill and tem stays on same place.

If that is normal then I guess till the summer comes, the ski jacket mode is on..

Also do not know is this normal but mu central vent always blow cold air, I just keep them closed..

[BenHar]

It sounds as though there is something wrong with your heater control linkage.

You should get hot air from all vents with the temperature dial set to max.

The face level vents should blow cool and the foot level hot with the dial set to half way.

Ben

[Brianmoooore]

You should get hot air from all vents with the temperature dial set to max.

The face level vents should blow cool and the foot level hot with the dial set to half way.

Ben

This is correct, and gives some credence to the last part of the last sentence in my last post.

[Brdjo]

hmm make sense.. but definitely middle vents blow cold even temp set to max..

I did notice when temp is set to cold (all the way left) and switch ignition there is some single clap like a flap door inside vent is closing or opening. when set to hot no clap sound.

How can I test or diagnose does linkage work, and narrow the problem down..

[Brianmoooore]

Does your temp. dial have numbers around it. I.e., marked in degrees?

[Brdjo]

No..

[ChrisHC]

hmm make sense.. but definitely middle vents blow cold even temp set to max..

The face level vents are meant to be colder than the foot vents, I think.

[clipper]

hmm make sense.. but definitely middle vents blow cold even temp set to max..

The face level vents are meant to be colder than the foot vents, I think.

I tested this feature this morning (because for years I could not get warm air out of the "face" vents).

I realised when reading this thread earlier this week that I had forgotten about this supposed defect in my car, even when I changed the heater controls a few months ago, I paid no attention to checking this.

But now, on fully warm, I DO get equally warm air from the face vents as from the widscreen vents (the footwll vents seem warmer, but that surely is due to their proximity to the matrix).

So it seems that by changing my heater controls and setting them up properly, I have inadvertantly fixed a 15 year old issue!!

[Brdjo]

Hmm nice to know I have one complete heater unit, so we will see what is going on.