Mine is leaking while running.
I hope to get and install the part tomorrow.
Pictures and text will be added here ASAP.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

Sounds good, well look out for it.

Weather delay.
Shipping terminal closed.
Parts will be in Monday...

#1. Open hood.
#2. Disconnect and remove battery.
#3. Remove weather seal from false bulk head = blue line in attached picture #A.
#4. Remove four access panel screws = red dots in attached picture #A.
#5. Remove access panel = pink line in attached picture #A.
#6. Remove the silver processor box from bracket and lay it back on the bezel.
#7. Remove the three hoses where they pass through bulk head.
#8. Trace the aux pump wire to the plug and disconnect it.
#9. Remove the wire from mono valve.
#10. Remove two 10mm bolts holding mono valve, you may need pliers to hold the bottom nut unit.
#11. Remove the upper hose from the mono valve.
#12. Remove the water feed hose going through false bulk head to aux pump.
#13. Remove the two 8mm bolts supporting the aux pump isolation bracket.
#14. Remove the pump and mono valve assembly as a unit, use great care.
#15. Note orientation of aux pump to mono valve.
#16. Remove aux pump from mono valve.
#17. Remove aux pump isolation bracket from old unit and install on new unit.
#18. Install new aux pump to mono valve with correct orientation.
Reverse order # 14. - #1. and you are done.

Mine was nasty; it took two hours in the shop with all correct tools.
I hope yours is easy.
Have a great day.

Attached Thumbnails

   

Great DIY. If anyone can confirm how similar this is to my 1991 190e 2.6, I'd appreciate it.

__________________
1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

take time to put in a 1 amp in line fuse so if it (aux pump ) fails it does not fry your ACC unit, sounds like you caught yours in time

This is an awesome idea if confirmed it works. Please tell me a little more about how and where to put it.

__________________
1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

The fuse is easy to add.

whunter:
You made no mention of draining the cooling system, did you do this first?

__________________
1991 M-B 560SEL Arctic White/Grey 99,000 Miles
1987 M-B 300SDL Ivory/Palomino 229,000 Miles (sold but never forgotten)
2006 Volvo XC70 Blue/Beige
1999 Porsche Boxster Arena Red/Savanna Beige
1986 Porsche 928S Goldweiss/Brown

Whunter....can you explain the purpose of this pump?

Does it just feed the ACC?

As always, I appreciate your detailed documentation!

__________________
1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif

As I understand, the pump is there to provide adequate water flow to the heater core when the engine is at idle or low rpm. At road speed it is not really required.

__________________
1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

There was no need to drain the system.
Total system loss was roughly 1/2 quart.

It is there to flow hot coolant through heater core at low engine RPM.
Without this pump, most drivers would never have heat.
I met an older woman today, she owns a 1984 300SD since new, and is proud that it has never been above 2000 RPM, she drives it 25 miles every Sunday.

here you go, as explained to me by several Mber's

To protect your circuit board from future burnout, install a one amp in-line fuse in the power supply wire to the auxiliary electric water pump. The pump is under the hood, - it is buried between the two firewalls in 126 models (S-class). If the pump motor binds up, this fuse should blow, preventing burnout of the printed circuit board.

Thanks whunter, I have to replace mine and was wondering if I could without draining the whole system.

The in-line fuse sounds like a good idea. When I purchased my SDL both the Aux. Water Pump and A/C Compressor Clutch were unserviceable. Both are protected by the same fuse (#5). I'm not sure if their failure was coincidental or one took out the other. The A/C Clutch was shorted out and the Aux Pump appears to be seized. The fuse blew until the Clutch was replaced and the pump disconnected (present state).

I see many posts regarding the possible failure of the Climate Control if the Aux. Pump fails. What causes this and what are the likely symptoms?
My ACC works OK although it doesn't seem to regulate very well.