Temperature gauge problem 320i

[ah]

Ive changed the thermostat and the heating is spot on,but the temp gauge goes to the quarter mark and occasionally 3 quarter.Also when I stop and turn the engine off,when the engine is restarted the temp gauge will have dropped and takes a while to read OK again.I have checked the brass nuts and they are OK and tight.

[SGP]

You may have a thermostat that opens at a lower temperature than the previous one, iirc that would cause the gauge to display a lower reading. That happened to me in a ford transit some time ago. If you haven't already, check/clean the sender connection on the engine.

[capri_rob]

Gauge definately should not go past halfway - IIRC the gauge is non-linear - i.e the "normal" range is between 1/3 to halfway on the gauge and only covers a few degrees of temperature - anything more is too hot.

If its definately not a gauge fault sounds to me like you have an airlock somewhere in the system.

You can try checking/changing the brown sensor on the engine as this sends the signal to the gauge too but my money would be on an airlock.

Bleeding M20's can be a pig - if you've got Andyboys restoration bible it gives a very comprehensive description of how to do it without getting airlock issues