W124 300TE - Heater problem, fixed

[Vectrolosys]

Hi All,

Just wanted to regail you with an experience I have recently had with my W124 and the heater. Due to various reasons, the heater has not been blowing hot. This occurred after the car had been sat idle in the garage for nearly a month.

Anyway, a quick check when the heater dials were on full, revealed that the heater electric aux pump was working. A quick tap with a rubber mallet, to each of the two solenoids spurred them back into life and heat to the cabin was restored. They are slow to re-act, so replacement is probably on the cards!!

James

 

[wellshj]

Another note to append to this handy tip WRT the duo valve is first to double check that the coolant level is absolutely up to the required level. I've just fixed this on my 300e - the level was a touch below (but not low enough to trigger the warning light) and causing intermittent heating, presumably due to airlocks.

 

[wellshj]

Actually a full recap to cover other stuff that I turned up when researching the problem is probably handy so here are a few tests I picked up:
- Check voltage on 3 pin plug on duo valve changes with extremes of temperature dial setting then you know that the dash controls are working OK
- Feel auxiliary water pump for vibration with ignition on then you know that this is OK. (this only seems to have a marginal effect on actual heater performance though)
- Feel temperature of two pipes leading from duo valve into cabin to check if valve is opening (if warm and no heat then could be blocked matrix)
- Duo valves most often fail in the open position. Tapping, rebuilds and replacement are all possible to rectify.
- Issues with temperature regulation might relate to the cabin sensors. I didn't get far enough to check this out fully but tests seem to involve checking for suction at vent above rearview mirror, among other things.

 

[Glennboy]

Me w124

I seem to have the same problem. No heat at all and iv checked the duo valve by tapping it but no success so i am replacing the thermostat tomorrow. All in all when ever i get it fixed ill post the full problem and the cure

 

[djwazza]

Possible Duovalve issue?

I've been reading these heating threads with interest as I have been freezing my 'toes' off over the last 2 months due to no heat on the drivers side, and yet full control (and heat) on the passenger side. Am I in the correct territory with a Duovalve replacement? I've just ordered one through 3-Pointed and am hoping it will be a quick fix.

 

[coupe deville]

Yes, my money would be on the duo valve

 

[djwazza]

Wrong valve has just arrived...

Thanks for the reply, the valve (incorrect version) turned up today. My quest for warm toes continues!

Anyone have a facelift E300D duovalve out there?

 

[optimusprime]

help

Also problems like this can also be your circulation or auxiliary water pump is not working .The hot water wont circulate if faulty .Duo valve is faulty if heat only coming from one side , there is a video how to replace parts inside on youtube. Very easy to do.

 

[bolide]

The E300 Diesel Duovalve is unique to that car. The chances of finding one will be slim

There are lots of oddities on that car. There's a water / oil heat exchanger that few people know about, the gearbox is controlled by a vacuum system and even the cooling fan rotates in the opposite direction!

Nick Froome