temperature sensor on w124

[mekon]

not sure if this should be in here or engines.
picked up my w124 last night, 300D
temperature gauge decided to shoot from normal to off the chart, i pulled over to cool the engine and if necessary top up the radiator which has a small leak, however the engine didnt seem very warm at all, touched the top of the radiator reservoir and it was cool, gingerly undid the cap to first stop.... nothing happened..... carefully undid it completely... system has water in..... turn the key in the ignition and temp is back down to normal, drive on, temp gauge starts jumping like a cricket, then seems to settle at a low temp (compared to my mums 230TE)

do the diesels runs cooler?
is it hard to change the temp sensor? as i think it is on its way out

 

[Neebo]

If it is overheating and the water is not circulating I.e the radiator is not getting hot the impeller may have broken off the water pump?

 

[grober]

Wonder if you have a thermostat problem?

 

[drussellwilks]

I have a similar problem with my W124 estate, and I am sure it's the gauge not the sensor. If you give the gauge a tap if often returns to normal again, it might be worth trying this next time it happens. You can usually tell if the engine really is overheating by the way the car feels.

 

[mekon]

car felt fine, but the temp needle is very twitchy, it will flick up to high then back to normal position so hoping it is just the sensor, when i get a chance i will run her up and leave her idling then see if the rad gets warm

 

[kth286]

air locks ?

 

[Fullmeister]

Mine has the same problem but if you lightly tap the dash above the gauge it returns ...... its called "character"

 

[mekon]

lol "character" indeed

 

[mekon]

*update*

had the car idling for about 20 mins while i poked about, engine didnt get up to temp :s popped the bonnet and the radiator was cold, the fan was turning :s but the engine seemed pretty darned cool, normally you open a bonnet and the engine radiates heat but this didnt, do diesels run cooler by design? might explain why they last soo well