'79 300D Water Questions?
 

Looked at a guys 300D that didn't have heat the other day. Turns out, there's a funky water direction valve on the right side fender well that has a cracked housing and has bee bypassed.

So, who can tell me what this is, how it works and how I can bypass it to restore heat to the car:

http://mercedesbenz.port5.com/images/300d_1.JPG

and

http://mercedesbenz.port5.com/images/300d_10.JPG


Also, should there be a vac line connected to this alda (again, on the '79 300D)? Routing?

http://mercedesbenz.port5.com/images/300d_alda_2.JPG

Big plastic box with lots of wires up top and four hoses underneath? Climate control servo -- get an aluminum one from Performance Analysis, along with the amplifier (it's dead too, and will fry the new servo if not replaced...) About $600, I think. Factory parts, if you can get them, are about twice that.

Someone has posted a way to bypass it, I don't remember the thread. Will only have full heat, though, unless you rig up a flow control valve.

Peter

No vacuum line. It's just reading atmospheric pressure in the non-turbo 617.

The dreaded ACC Servo
 

Somewhere there is an engineer who is laughing his a__ off at supplying a design like this to the automotive industry.

Maybe it's the guy's son that rebuilds them. Who knows, but if it's cracked you can bypass using tubing and as Peter poiuinted out it is constant heat. The good thing is that the troubleshooting is pretty simple. If it doesn't work, it's broke...;) No fixing those babies.

Anyone here done the bypass on this unit and can share just what needs to be hooked where?

Pics instead of long explanations would work well. Have a guy in Boulder Biodiesel who's commuting in his 300D without heat (here in Colorado), would like to do what I can for him and since I'm mechanically inclined and out of work and he can't work on cars as he works as an accupuncturist (I do too sometimes, but just on myself...., with screwdrivers and such!)

BTW, by constant heat, do you all mean that there's just no A/C and just heat when the fan is turned on, or that the heat will be on at all times, no matter what? Will it still get hot in the drivers compartment if the fan isn't on?

I suppose having collant run through the heater core 100% of the time isn't all bad, unless there's enough flow-through to make it hot inside even when the fan is off.

Will any adjustment help, as with the turbo alda?

There's a whole thread of this somewhere in the past. I believe it is quite simple. There are two heater hoses coming in and two heater hoses going out of the servo. Disconnect these lines from the servo and hook them together with two pieces of pipe (copper or pvc). Then the coolant has no hindrance to running freely thru the heater core.

No adjustment. Face it, the 300d NA's are dogs at our altitude.