so using these two parts and some vac line

https://www.amazon.com/gp/product/B003R34VMU/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B003R43J2C/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

the water valve is normally closed so when the heater is on the electric pump runs so using that for activation to the solenoid it applies vacuum to the water valve opening it

the solenoid self vents so when no heat call the vacuum is released causing water valve to pull shut

i unplugged the pump as it is no longer needed

i will try to answer questions, easier to hook up than to explain

under $30 bucks too

i do have a couple of poor pictures but don't know how to post them

hope this helps

__________________
85 300d in progress

Looks simple but how to regulate the water flow to get the heat level you want ? .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

mano valve circuit is an option also but I'm thinking the climate control also cycles the pump when closing the mono valve but yet untested as its too hot out still

the mono valve applies 12v to close and i apply 12v to open the valve so i might have to see what happens

Steve

__________________
85 300d in progress

So basically this?
https://klimakit.com/product/monovalve-and-coolant-circulator-pump-eliminator-upgrade-kit/

__________________
2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

Ditto, as dude99 said, I remembered the Klima kit, which is based on M-B parts for later years, if that is important to you, otherwise cheaper parts (Chevy or Toyota in U.S.) can work. Just insure the polarity is correct (12 V applied to solenoid closes the water valve).

Re the "aux pump" which fireman mentions, long gone in my 84 & 85 300D's. A section of silicone hose works just as well w/o risk of coolant leaks or cabin fire. That electric pump is just one more over-engineered silliness by M-B.

For my mono-valve future, I have one from a 1986+ 300D, which are still inexpensive, especially used on ebay. Once I run out of factory parts, I'll install it where the aux pump sat, extending the wires to reach.

I wondered in the mono-valve is opened proportionally (servo) or just on-off control. Either would work. If the drive element is a relay, then it is certainly on-off, but I would think then they would use "high-side control". Instead, they supply 12 V to one side of the coil and use "low-side control", as was common for transistorized controls in the 1980's and still seen in most engine controllers today. With a transistor, it could be a proportional output, but more likely would still be a simple on-off control. The reason it matters is that a proportional control loop could go unstable if the control elements are changed.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

yup

__________________
85 300d in progress

fm:

In the original installation of the diaphragm operated water valve (GM?/Toyota?), do you know if it is installed in the hot (inlet) side of the heater core, or in the cold (exit) side?
If it is suitable for use in 80C+ water the system operation can be improved with hot side control.

i put it in place of the mono valve on the cold side. not sure of the original design

__________________
85 300d in progress

A bit of internet rooting around reveals this:
> there are two related valve P/Ns, 1021C & 1022C; one is normally open, the other normally closed
> these are replacements for Ford valves used in mid-80s Escort, and 2000s Ranger
> Ford hose diagrams show the valve installed in the hot side

I personally don't care about the automatic feature in these cars. I always have the thumb wheel at the fully locked position of either end of it's travel. I just adjust the fan speed and point the vents in a comfortable position. A simple on/off flow of coolant to the heater core is appealing to me. With many of these cars having suspect monovalve operation, I usually just install a 3/4 PEX ball valve (perfect size nipples for the hose) in the hose (hot side of core) above the oil filter canister. However, this does have it's pro's and con's. The pro being there is no way any hot coolant can get into the core for A/C use. The con is that sometimes I need heat in the morning, and A/C in the afternoon. This makes it a hassle to open/close the ball valve twice a day. Having a manual heater valve that is controlled from the cabin is a great idea. As far as using the coolant pump for the open/close signal, I would probably use a relay to be on the safe side. Better yet, I would be inclined to hide a rocker switch that I can toggle back an forth that opens/closes the heater valve, without opening the hood. Total manual control is best for me. YMMV

__________________

All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html