Why does m20 not run up to correct temp.

[ah]

It occasionally runs at 11-12 o'clock position at stand still,but start driving and it drops to 1/4 or just under,yes I put a new stat in.It runs lumpy and juddery generally but seems to improve when it reaches correct temp.Could it be I have an air lock in the system?

[daimlerman]

Sounds about right to me,anywhere between the three white marks can be regarded as normal.

[pnd]

maybe running an oversized rad.

[daimlerman]

maybe running an oversized rad.

This should'nt affect overall temperature at normal road speeds,but increased capacity to the cooling system will help maintain proper temp levels.

[BenHar]

Six cylinder cars use an 80deg C thermostat and run at just above the first quarter mark.
Four cylinder cars use an 88deg C stat and run at about the half way mark. (Dunno what it is for the M3.)

If yours is going up to half way when stationary the viscous coupling on the fan may be getting tired.

Ben

[Morat]

My 325 runs bang on half way, but there is variation because the gauges are pretty sensitive.

[B7]

If its not running right when cold (or until it reashes temp) I'd say a faulty temp sensor is likely.

But that wouldn't explain it running cooler until at rest. Fan clutch stuck on?

[BenHar]

My 325 runs bang on half way, but there is variation because the gauges are pretty sensitive.

You've probably got the wrong thermostat in it.

Ben

[e30den]

My 325 runs bang on half way, but there is variation because the gauges are pretty sensitive.

You've probably got the wrong thermostat in it.

Ben

Halfway is bang on , well actually its my e46 that runs halfway the e30 runs at 11 oclock and that after a spirited drive