Car is a 1979 240D. Once in a while I get over heating at idle. When this happens appears to be little heat coming from heater. When I run the car on highway, it is set at temp fine (187 to 193 degrees F) but I do hear some gurgling in the heater core. All coolant levels are fine when over heating starts, overflow line discharges some coolant. Water pump and belts are in order.

Car was flushed and filled within a few thousand miles which for me can be a week or two or highway driving.

I have tried to open the screw on the top of the thermo housing to see if air can be released. Highest point in the system is the heater control modulating valve on the fire wall with three hoses connected.

Any other way to bleed this system I am not thinKing of please? Is there a cook book method not in the MB manuals but this vast source of knowlege is aware of?

Regards Tom

Park nose up on a steep hill and run the system with the heater full blast for a while.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

If that doesn't do it ADD.... disconnect heater hose (from head to fire wall on drivers side) at the fire wall, wire it up then disconnect the upper radiator hose at the head and pour coolant in it till it comes out the elevated heater hose.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Thank you/Tom

The heater control valve closes upon power application.

It's a 240D with manual climate control.....

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Ah... I was duped by the "wire it up" part!

Yah, I shoulda said, Wire it up so its higher than the upper radiator hose that your pouring the coolant into, but I thought that would be obvious when you were actually doing the job.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"