Author Topic: Heater Valve removal  (Read 1685 times)


  • Guest
Heater Valve removal
« on: December 22, 2021, 22:47:58 »
Thought I would share an additional way to remove the heater core valve.
1. I read a few posts and used the the technique from Joe to tap it in first to loosen it. 
2. To extract, I used a long M4 screw and a dent puller. A few impacts and it came out easily.

Picture attached. My core is removed, may work in situ as well.

Hope this helps.


  • Associate Member
  • Gold
  • *****
  • Southold, NY
  • Posts: 504
Re: Heater Valve removal
« Reply #1 on: December 23, 2021, 11:59:40 »
For those who may be interested, here's a picture of the original M-B tool, part no. 180 589 023 300, used to remove the heater valve core. Good luck in finding an example. BTW, the end of a spark plug uses the same 4mm thread that fits the hole in the core.


  • Full Member
  • Gold
  • *****
  • USA, IL, Willowbrook
  • Posts: 646
Re: Heater Valve removal
« Reply #2 on: December 23, 2021, 21:03:49 »
You have to appreciate how shared ingenuity makes a daunting task easier. From head scratcher to simple fix.
Frank Koronkiewicz
Willowbrook, Illinois

1970 280SL Originally Light Ivory - Now Anthracite Gray Metallic


  • Full Member
  • Junior Level
  • *
  • USA, SC, Charleston
  • Posts: 14
Re: Heater Valve removal
« Reply #3 on: January 22, 2023, 17:53:26 »
Just a small addendum to the above topic for anyone completing valve core removal...just completed core and O ring replacement of original which was still in car...
1. Punch it down a "short"  distance to remove retaining clip i.e. just enough to slide the clip out.
2. Use a magnet to hold arm, clips, screws and washers from falling into cavity..and use it to recover them if they do fall down. 3. Old O ring appears to be square cross section whereas new one was round cross section.
4. Spray small quantity of Houdini lock smith oil which penetrates, cleans and lubricates with suspended graphite...makes removal easier.
5. If you do push either new core or old core too far into body, the ring will catch on inlet port when you attempt to remove and appear to be stuck.
6. Take a very thin plug gap wafer and slide down to prevent o ring from catching and slide up and out..6.Using magnet put everything back in place exactly where it was before dismantling....

Works perfectly and now have heat in cabin with slide that opens and closes easily..
Ten minute job if you exclude the 2 hours or so looking for plug gap wafer, dropped screws and washers, scratching head, looking up tech manual for process and going to store for another O ring damaged during learning process..
1971 Automatic S/N 020513
670 Light Ivory
040 Black Pagoda


  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7317
Re: Heater Valve removal
« Reply #4 on: January 22, 2023, 20:56:03 »
Some other things to consider: if your heater valve is hard to operate, conduct a cooling system flush. While the flush is still in the system, warm the engine to temperature and operate the heater valve. The process usually cleans up and frees-up the valve. It's quite amazing how well this works sometimes. Another trick to freeing up the water valve is warm engine and disconnect the coolant line in the engine compartment, next spray penetrant into the metal pipe going to the heater valve. Use the little red plastic tube which comes with most penetrant cans, to reach as far down the pipe and as close as possible to the valve. Exercise the valve and repeat if needed until everything is working nicely. If the o-ring is leaking removal is necessary of coarse.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback