Heater Valve Adjustment

[Pawel66]

I know that pretty much everything was said about the heater valve, but I have not come across this piece of information, which may be important for some of us.

If you have hot air coming to driver's side leg room, the reason may be the heater valve that is not closing or not tight. The reason for heater valvce letting coolant go to the heater may be just adjustment of its push rod. Just check it before you dismantle the vlave.

Just look at which direction the push rod is pushing the valve lever when you close it. Remove the rod from lever and see if you can turn it further in the same direction. If yes, then check if the vlave is tight when you push it to the end of its travel with your hand. If it is tight with your help by hand - you may just need to adjust the push rod length.

Checking the valve for tightness: disconnect the coolant hose from the heater inlet pipe in the firewall on the driver's side, where the valve is and fit a piece of hose to the heater inlet pipe in the firewall. Close the valve and blow in that fitted hose gently (!). If nothing heppens - good. If you have a fountain of coolant coming out of the hose you disconnected from the inlet pipe making mess in your engine bay - vlave is not tight.

I just went through it today. Ended up just adjusting the rod lenght.

If this is genraly known - sorry.l

[StevenF]

I recently had heat coming in from the driver's side leg area but discovered that it was coming from 2 small "holes" in the steering column.  Where exactly is your coming from?

I will be taking pictures soon once I insulate the cabin with material I just ordered.
While driving on the highway, I reached under the steering column, I felt air coming through.  Once I plugged the holes with my fingers, the air stopped coming through.

[mbzse]

I know that pretty much everything was said about the heater valve.../...

One interesting fact to be aware of - the parts of the heater valve can be assembled in 32 different ways!
However, only one is correct...
I.e. will allow the full amount of coolant to flow into the passenger compartment heater element

[Pawel66]

I recently had heat coming in from the driver's side leg area but discovered that it was coming from 2 small "holes" in the steering column.  Where exactly is your coming from?

On my quest to restore my car I came across heat coming to the leg room several times. I did have the hot air coming through various holes in the firewall that were not properly sealed. There is plenty of grommets an gaskets there.... I took care of all those. A flash light inside in the dark garrage helps. Then the heater valve not closing completely was the recent one I fixed yesterday.

[Pawel66]

One interesting fact to be aware of - the parts of the heater valve can be assembled in 32 different ways!
However, only one is correct...

I obviously had no idea about it .

In the heater valve fixing procedure in Technical Manual we have it very clear: mark the orientatin of the elements, draw the orientation of the elements etc. very clearly.

Imagine try and correct 31 times before you get it right?    Would this be the the worst luck ever contest winner?

[thelews]

I cleaned the valve and replaced the O-ring 3X13 ID mm on my valve last night since it was binding and I didn't want to risk breaking my original dash temperature control. 

I don't see what the issue is with orientation and all kinds of diagrams and marking.  You replace the valve in the open position, hole facing the pipe.  The tab goes on top of the valve through the slot so that it is at the full open stop.  The straight edge of the tab faces the closed position.  The ball lever installs on top of the tab to meet the socket (properly adjusted for length) in the full heat (open) position.  Once the socket is connected, make sure it closes fully and adjust socket as needed.  You're done.  Anything else and you're 90 degrees off and it's obvious.

BTW, the screw end of a spark plug screws into the valve and makes a nice tool for removing and installing.

Coolant is generally enough lubricant for replacing the valve, but I use just enough Vaseline to make it slippery when installing the O-ring and the valve (you can't see the Vaseline but can feel it).  Once installed, good coolant keeps it lubed, until it gets stiff again!

[wwheeler]

Yes, be sure you use a metric O-ring and one meant for coolant!!! Do NOT use a hardware store O-ring because you do not know what material it is made from. Rubber meant for oil is not necessarily good for hot water. The 3mm metric size is VERY close to an 1/8" sized O-ring. But the 1/8" O-ring will bind the heater valve. The metric size is a must.

You can buy a waterproof grease meant for bathroom fixture O-rings. That is what I use for these O-rings and can be found at any home improvement store. 

[ejboyd5]

M-B tool # 180 589 023 300 for valve core removal.  Or, as said above, use a spark plug as a tool.  The 4 mm threaded end fits the core perfectly.

[thelews]

I got my O-ring supply from McMaster Carr.  I don't remember the material I chose, but they've been sitting in the 190 SL with the same valve style for years.

[wwheeler]

McMaster is a great resource for O-rings, raw materials and metric hardware. They have rubber sheets and gasket material you can use to make gaskets if needed. And for me, the best thing is that you know exactly what you are getting. You can choose the type of material and different hardnesses.

Everyone should know about McMaster. The only downside to buying O-rings and hardware there, is that you typically have to buy a 100 or so. Still, a great resource.