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Discussion Starter · #1 ·
What would happen If I removed the aux pump from my system? I'm mostly only curious, but I ask becuase it would facilitate an easier installation of the circulation tank heater I bought. Does that pump stay on constantly when the car is running or just turn on as needed?
 

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1984 300D (235,000 miles), 2001 E430 (78,100 miles)
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I assume you're talking about the small electric pump in the heater line, located roughly behind the alternator.
While I don't know what turns it on, it's purpose is to provide increased coolant flow to the heater at idle for better cabin heating.
If I understand correctly, if it locks up or in some other manner malfunctions, it can do unfortunate things to the ACC unit.
I didn't feel that I was deriving any particular benifit from the aux pump, so I had no problem w/ removing it. I got a 90 degree elbow hose of the appropriate size, and found that the pipe going to the firewall is a smaller size than the one going to the water pump, however, it was close enough such that I was able to persuade the hose over the larger pipe.
Personally, I've not missed having the aux pump, and the cabin heat I'm getting seems perfectly adequate.
 

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Discussion Starter · #3 ·
Thanks for the information, I think I'll take it out and install my heater tank in it's place.
 
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