Okay, the previous owner said he repaired the heater core, had it pressure tested and it should work fine. After being mystified by a wet carpet, I discovered that it wasn't water but coolant. I traced it to a clamp on the valve the driver's side. I tightened it as best I could and I think I've got it licked. I'll probably replace all the hoses and clamps with Mercedes parts next fall. That brings me to the heater that won't stop heating. I set it on cold (or no heat), I can see the valves move but I still get hot air. Maybe not as hot as it is when it is set to hot. Summer's coming and it won't be pleasant this way for sure. Any thoughts on where to start looking?

__________________

Michael Maddalena
Mint2Me.com
Warren, Connecticut
203.417.6856

Todays great finds at: http://www.mint2me.com
Follow us on Twitter: http://twitter.com/itsmint2me

I think this valve setup is the same as on my 1970 220. I recently replaced the o-rings and I noticed that the position of the valves still allowed some coolant to flow even in the 'off' position. The top of each valve cylinder is machined to a "male" square section which the stop washer fits over and contacts the the valve housing for a full on or off stop on the temperature selector. In the 'on' position my valve was almost completely open; in the 'off' position the valve was nearly closed but would still allow some coolant to trickle through. This can be corrected by turning the valve cylinders 90 degrees in the valve housing to completely shut off flow in the 'off' position (though you'll have to disassemble the unit to know which way to turn the cylinder and to remove the stop washer). Curiously though, this correction restricted flow in the 'on' position with it only being about half open. I'm not sure if this is of any help, but I suspect if your valve control is similar to mine, you're not cutting off the flow of coolant. Maybe someone else can speak to this or has a spare valve unit they can inspect.

The little amount of flow helps reduce the buildup of scale in the pipes, core and valve. Some wee bit of flow is better than none at all.

Usually the little bit is so insignificant that the heater core just dissipates it normally.

__________________
Looking for Early 108 windshield surround wood in decent-to-good condition.

Very interesting to hear this. Glad I didn't "correct" the "problem"...

Could this low flow be generating the heat the OP speaks of?

I'm not sure, haven't seen finnie heater valves to see how much (how little) weeps by normally in the closed position.

The little bit that moves past is usually not enough to "heat the heater core" but rather the larger (cooler) mass of the heater core cools the tiny amount of coolant that goes past when the valve is "shut" so one doesn't notice it.

The more modern plastic solenoid controlled valves will actually shut 100% as some of those cars' heating systems will actually run through a full open-shut cycle after shutting off the engine. They will open/close the valves briefly as well as the internal flaps and diverted controls, just to exercise everything a little during normal operation.

__________________
Looking for Early 108 windshield surround wood in decent-to-good condition.

Here's the reply I posted to your question on the Heckflosse group:

This is pretty common. Do one side at a time. The easiest way to fix it is to
remove the lever from the valve and carefully push the valve in just enough to
remove the stop clip. Pliers on the square end and gentle twisting and pushing.
Then turn the valve 90 degrees at a time until there is no heat coming out of
the defroster. You should put the stop back on each time you start the car to
check it or the pressure could force the valve out. Put the dash control lever
on Cold and re-connect everything. Be very careful not to push the valve in too
far or you'll have coolant everywhere. And be even more careful not to let the
valve come out. This is somewhat time consuming but a lot easier than draining
the system.

Would the OP really need to drain the system to pull the valve assembly and actually see what he's doing? This is, I think, the highest point in the cooling system, and shouldn't require any draining to overhaul the valve assembly.

I just did this two weeks ago without losing an ounce of coolant. Might be worth it to pull the assembly and replace the o-rings while taking down a thorough description of which direction you're turning the valves and for what result. Just my opinion.

That's my point, which I may not have made very well. There is no need to remove the valves to fix the problem. It is time consuming but easier to turn the valves 90 degrees at a time and check the heater output than to drain the system just to look at the valves and risk putting them back in wrong again. If the valves are removed without draining at least the heater core there will be coolant all over the inside of the car. The heater is not the highest point in the system, and the valves are actually pretty low in the system. It's pretty easy to bypass the heater with a piece of heater hose or pipe and then drain the core if you want to. Also, I think the valves are different, right and left.

Maybe it was my point that wasn't made very well. It is not my experience that the cooling system needs to be drained to perform a valve overhaul. At least on my 1970 220 (so please keep this in mind OP, though I think it's the same) the hoses were "pointed up" and I didn't lose any fluid. The advantage of removing the valves, at least in my opinion, is that the o-rings can be replaced and one can actually note the valve positions and what a 90 degree turn in either direction would accomplish. Otherwise you're making blind choices and trying to "feel" for heat... which isn't always as straightforward as it sounds.

If the valves are truly low in the system and not high on the firewall (as they are in my 220) then perhaps we are talking about different setups. If the OP wants to post a picture I can comment on whether I'm wasting my breath here. In any case, a valve overhaul can be done in about 15 minutes (or longer if you're doing cosmetic work) and in my case both valve control cylinders were identical though I marked and dedicated them in the event of any uneven wear.

Not sure if this helps, I hope I'm not leading you astray. Let us know how it goes.

I want to thank everyone for their comments. Hopefully this will be helpful to other new owners in the future. For those of you that have a Fintail sedan, can you tell me the size O-rings I'll need? Has anyone changed the hoses without removing the heater box?

__________________

Michael Maddalena
Mint2Me.com
Warren, Connecticut
203.417.6856

Todays great finds at: http://www.mint2me.com
Follow us on Twitter: http://twitter.com/itsmint2me

Hi Mint,

If your valve unit looks like mine in this post (first picture, and it's viewed from the the right side of the engine compartment) then the o-ring size can be found further down in the post. All Best,

The 115 car has a completely different heater core. The valves for a 111 are 000 835 03 20 - right, and 000 835 04 20 - left. The valve on the 115 is shown as an assembly controlling both sides. The actual valves inside could possibly be the same since they have the same part number for the seal (o-ring). The seal for both cars is 000 835 58 98 and is readily available from MB dealers for a few dollars. Here's a link to the Ponton group site with a good R&R explanation for the valves: Mercedes-Benz Ponton Heater Core Valve Repair © www.mbzponton.org
Even though the heater cores are different in the Ponton the method of repair is the same. With a 111 it can be done with the valves bodies in the car.

I read this post while trying to gather info about this job, and am now posting my findings to help make this job a little easier.

My heater valve orientation was wrong. I took them out today after confirming with the warm weather that my heat is always on.

The orientation is simple, now: with your hand controls in the "heat off" position or "blue," the hole in the removable brass valve cylinder should be pointing down or directly at 6 o'clock. Then when you turn the control to "heat on" the valve will turn the hole to 9 o'clock on the left and 3 o'clock on the right side. That then directs the hot water to the heater core, eventhough it only seems to be partially opening the valve by a little over half way. That is enough to get plenty of heat. That is what initially threw me off, the valve hole doesn't really line up. You sit there staring at it wondering why don't these line up better? What is the German engineering reason for that? I am not sure you are even getting 50% open in the 9 o'clock position on the left, 3 o'clock on the right valve.

I had incorrectly guessed that the valves needed to be 1/4 turn closer to the water outlet. That caused my heat always on condition.

Much happier now with cool air coming form the vents.
said that these valves are the highest point on the whole coolant system. I don't know if that is true or not but I did this job with my car tilted down the steep part of my driveway just to make sure a minimum of coolant came out when I pulled the valves. Lots of coolant came out. I had to open the drain on the bottom of the radiator and drain a fair amount of coolant before none came out of the valve holes. FYI

This was on a w111 1965 220sb.

__________________
1965 220SEb Manual

The clip that limits movement can be turned upside down so that you can get a slightly different position when moved. I've also filed a bit off of one side so that I could get it to close further. In most cases you want the heat to shut off more than heat to come on given that these are summer driven cars.