Heater cools down at idle

[Marcus_uk]

I noticed the other day that the heater goes cold if I am stuck in traffic (idling). Once underway it gets nice and hot again. I have no cooling issues. Any ideas what this could be... air lock? Dirty heater that needs a bit of pressure (ie above idle) to get things flowing? Ive flushed out the system with that holts two part stuff though...

[RayD]

The lack of pressure at low revs sounds a likely candidate Marcus.

Did I read somewhere that the heater valve is prone to getting partially blocked?

Ray

[muley]

You could eliminate the valve by temporarily inserting a bit of straight pipe in it's place and see what happens.

If it were me I'd probably change the thermostat - easy and cheap to do and it might just be part of the problem ...

Cheers

Jim

[Monty]

If it were me I'd probably change the thermostat - easy and cheap to do and it might just be part of the problem ...

Cheers

Jim

[GeoffSmith]

Blockage or lower temperature at idle so in order of likelihood/ease of fixing: heater valve (see here how blocked they get before falling apart - I have one spare), thermostat stuck open (check with ElanScan and change if stuck open otherwise you're also wasting fuel), blocked matrix (DaveEds might have one) or water pump.

[Marcus_uk]

Thanks for the advice. Geoff i'll take the valve if its still going? I'll pm you regarding payment and postage etc...