Author Topic: Auxiliary Electric Water Pump: for Idle and Heat Soak  (Read 3529 times)

awolff280sl

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Auxiliary Electric Water Pump: for Idle and Heat Soak
« on: August 26, 2015, 16:56:09 »
Referring to topic http://www.sl113.org/forums/index.php?topic=22827.msg163355#msg163355 , I posted my set up for an auxiliary electric pusher fan for both the radiator and AC condensor that is triggered by a thermostat and/or the AC compressor. It is also wired to run for 3 minutes after engine shut off.
Recently, I read an old post by Dan Caron where he referenced the electric water pumps used by MB in the 1980s.
I decided to plump one into my heater bypass circuit and to have it run when the car is idling, as well as run during the 3 minutes that the aux fan runs after engine shut off.
My heater bypass setup uses a 3-way valve on the intake side of the heater, so I put the pump on the right side. This is the pump I used: http://www.amazon.com/gp/product/B001CO6ZHA?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00 .
To reduce heat soak, the pump is triggered through the same falling edge relay that controls the aux fan upon engine shut off. It is very nice to watch the temp needle go down, rather than up, when I shut off the car in the hot Florida sun.
To keep the temp at 180 when idling in traffic more than 10-15 minutes, the pump is triggered using the microswitch setup originally designed for the 2nd solenoid on the FIP (in some models).
I found the updated version of the original microswitch at https://www.alliedelec.com/johnson-electric-v9n/70162342/ . My AC system uses an idle kick-up solenoid, but the microswitch has enough play in it so that the bolt that pushes its pin can be adjusted to keep the pump on when the solenoid kicks up the idle.
For the winter or driving up North, I installed an on-off switch for the pump for when the 3-way valve is open to the heater core.
1st picture: shows heater bypass setup, with 3-way valve and electric pump.
2nd picture: shows the pump.
3rd picture: shows the microswitch
Andy   Sarasota, FL
'69 280SL 4speed
'06 Mitsubishi Evo

georgem

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Re: Auxiliary Electric Water Pump: for Idle and Heat Soak
« Reply #1 on: August 26, 2015, 20:11:02 »
Wow, a bit beyond us back yard, shade tree mechanics - well done.
George McDonald
Brisbane
230 Sl
1973 VW Kombi Single Cab Ute
2022 Volvo XC 40 Pure (100% electric)

ja17

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Re: Auxiliary Electric Water Pump: for Idle and Heat Soak
« Reply #2 on: August 27, 2015, 12:34:21 »
Nice job Andy!
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

awolff280sl

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Re: Auxiliary Electric Water Pump: for Idle and Heat Soak
« Reply #3 on: August 27, 2015, 12:49:08 »
Thanks Joe and George. It was tedious running the wires (neatly) and making (solid) connections, but really not a difficult job compared to heavy-duty work on an engine, drivetrain, suspension, etc.
Andy   Sarasota, FL
'69 280SL 4speed
'06 Mitsubishi Evo

Benz Dr.

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Re: Auxiliary Electric Water Pump: for Idle and Heat Soak
« Reply #4 on: August 27, 2015, 16:19:48 »
I figured that auxiliary water pump would work nicely. Great job!
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC