Question regarding cooling system

[bplust]

I have a question regarding the coolant flow through the engine to the heater core. Am I correct in saying that coolant does not flow through the piece of heater hose that passes over the oil filter housing until you turn on your heater blower, and circulates through the engine via convection and no further until the auxiliary pump is on?

Also, does anyone know why there is so much more coolant plumbing on the firewall of my 1985 300TD versus my buddy's 1981 300TD?

Thanks!

[toomany MBZ]

There were many changes on the '85's.

Originally Posted by bplust

I have a question regarding the coolant flow through the engine to the heater core. Am I correct in saying that coolant does not flow through the piece of heater hose that passes over the oil filter housing until you turn on your heater blower, and circulates through the engine via convection and no further until the auxiliary pump is on?

The hose near the oil filter is the supply to the heater core, it will have flow whenever the heat is "turned on." The auxiliary pump is intended to ensure good flow at idle, but the engine water pump will also cause flow through the core when the engine is running and the monovalve is open. What are you trying to accomplish?

[bplust]

I'm try to accomplish two things:

1. Understand the system better

2. Relieve airlocks that were occurring when I would hook up my extended coolant plumbing for my vegetable oil system. This thread: Question about coolant hoses in engine bay for WVO install was VERY helpful.

Thanks for the replies.