24v coolant flow - can someone educate me?

[NickL]

Currently my car is setup as an OBD1 S52, running an OBD1 spider hose and M42 radiator. My throttle body heater lines are bypassed, and the nipple in the head removed and the port used as one of my temp sensors.

So, I'm planning on running a custom radiator setup next year. I just want to clarify the purpose of all the ports on the radiator. Upper and lower is obvious, but I was curious as to how the integrated expansion tank and the 3rd port at the bottom of it work? I know that hose comes from the spider hose, but in relation to coolant flow, how does it work?

[DesertBMW]

tank is separated from the radiator flow, other than bleed on the top. It is not good design, you want the tank to be higher than the radiator and engine, like 325i is.

[Wanganstyle]

Currently my car is setup as an OBD1 S52, running an OBD1 spider hose and M42 radiator. My throttle body heater lines are bypassed, and the nipple in the head removed and the port used as one of my temp sensors.

So, I'm planning on running a custom radiator setup next year. I just want to clarify the purpose of all the ports on the radiator. Upper and lower is obvious, but I was curious as to how the integrated expansion tank and the 3rd port at the bottom of it work? I know that hose comes from the spider hose, but in relation to coolant flow, how does it work?

retain the original M20 overflow bottle or use a late model m20 overflow bottle in e30 position. The late model M20 325 overflow bottle is used in the e36 in euro models including e36 3.2 evo 321hp M3

use a 6 cylinder radiator; the late model 325 M20 radiator is the same part number as e36 325/328 radiator.