W124 Heater Not Quite as Hot as it once was

[tjamesbo]

I've noticed recently that despite my Engine getting up to operating temp the heater air is not quite as hot as it was years ago and as i have reptilian blood I like to be very warm in winter.The Temp guage is up around 80-85 round the 80 end on a cold ( as per the -4/5 days recently ) The heater does seem to go even cooler when idling in traffic. All of this means that despite my love of seeing that three pointed star in front I am beginning to think lovingly of My old volvo with its brilliant heatder and its heated Seats - boy do i miss those.
Could it be a valve on the way to the Heater or a sludged up heater matrix as i said from the warm up and engine temp i think the stat is operating Ok.

Thanks

 

[Cole@MBS]

Sounds like a clogged matrix, try a back flush!!

 

[television]

Its normally the duo valve stuck, 56 and 53 in the link.

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=F&cat=15U&SID=83&SGR=180&SGN=04

There is a good article on how to check in the DIY section

 

[wireman]

It may be the little pump on its way out, you can just see the motor shaft, check if its turning when the ingnition is on.

 

[Smudge]

Pretty sure the small pump is only to circulate water when engine is slow running or 'stat closed so would make no difference here.
More probably the duo valve, however I think they usually stay open when open circuit so water should stay hot

 

[television]

Pretty sure the small pump is only to circulate water when engine is slow running or 'stat closed so would make no difference here.
More probably the duo valve, however I think they usually stay open when open circuit so water should stay hot

Yes they do normally fail in the hot mode, unless it has just stuck some where in between,,actually the pump does quite a good job of circulating the heater, and they can stop