w124 230ce

[fast-eddie]

MY heater works fine when full on.
Problem is when temperature dial is between 22 ...24 and I'm idling in traffic.Air goes cold and only starts to rise when rev's rise over 2000rpm
then everything is fine until idle again. My car has no aircon.
Anyone got any ideas.

 

[Spike]

Are you positive that the temperature in the car hasn't reached the 22 mark thus swiching off the heater?

My W124 CE does similar but f I open a window and let some cold air in, the thermostat registers the different temperature and the heater swiches on again.

 

[Spike]

Are you positive that the temoerature in the car hasnt reached the 22 mark thus swiching off the heater?

My W124 CE does similar but f I open a window and let some cold air in, the heater swiches on again.

 

[Scooby]

Sounds like an air lock to me, check your cooling system leaks first.

Has the engine boiled dry at some point? If there are no leaks, it could possibly be that you have a very minor crack in your head gasket allowing small quanities of air into the cooling system and causing an airlock - pressure testing each cylinder with the coolant system drained may disclose this.

Have you also checked under front footmats - a leaking heater matrix?

Failing all that, it may just be that the coolant system needs bleeding properly, since this is the easiest intervention try it first, paying attention to any pipework that is near the height of the coolant filler.

I would say, I'm not familar with your specific model of car, but those checks would broadly apply to most vehicles.

 

[NormanB]

Is there not a separate wee pump on the cabin heater circuit to boost cirulation through the heater matrix when the engine is a t low rpm? Maybe this is playing up (fuse/wiring/poxed motor)?

Under the bonnet, follow the lines back (heading towards the front of the car) from the duo valves which are behind the firewall.

NormanB

 

[fast-eddie]

Tried opening the window ..didn't work.
No obvious airlocks, coolant level constamt for months.
Then checked circulating motor mounted on chassis rail below coolant expansion tank.
Motor is Fu%&@D caused by seized impeller attached ...looks like it was caused by corrosion ....lots of rust gunge etc.
Spot on NormanB.