My coolant seems to be plumbed differently than the other 300D's I have seen, most of them from later years. On the ones I've seen, the coolant hose coming out of the engine goes straight into the firewall. However, mine routes around and goes into the bottom of the aux pump. I'm trying to figure this out because I'm installing a two-tank wvo system and need to tap into the coolant system.

I've attached a couple pics and have numbered the various hoses in the order that I think the coolant is flowing. If someone can tell me if this looks right, I'd appreciate it.

As I see it, the coolant comes out of the engine (hose #1), loops around to the bottom of the aux pump (hose #2), then goes to the servo (hose #3), then from there into the passenger side firewall (hose #4), back out the driver side firewall (hose #5), then back around to the servo and out the other side of the servo (hose #6) which loops under and towards the thermostat.

Attached Thumbnails

   

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1980 300D, 128K

that seems like a norm autotempII climate control routing. Just like my 77 when first got it before converting to manual climate control.

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

So I was going to tap into hose #1 for coolant heading towards the wvo tank. Trying to figure out where would be best to tap into on the return. I was thinking hose #5. It would make it easy location-wise.

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1980 300D, 128K