M30 Heater Core Bypass

[theBMWbeast]

When it rains it pours...

Heater core blew up, tried to bypass it for the time being by connecting the inlet and outlet hose.
https://ibb.co/cLGjYRQ
(I’ll add that 1 and 2 go originally to firewall and aux pump, respectively)

Drained and refilled the coolant system, replaced radiator (needed to do it figured now was a good time), bled the coolant system. Then again, and again. Car begins to overheat after about 10 min of idling. Bled quite a few times. Never has gotten into the red. Came close on a test drive around the block, shut it down and waited a bit, of course.

Am I doing something with the routing to circumvent some fluid from the radiator or something similar? If so how do I alter my routing?

[shogun]

here is a detailed coolant flow diagram on pages 25 and 26 of the M70 engine, take half of that and you have the M30 http://bmwe32.masscom.net/moswald/docs/BMWv12manual.pdf
1 radiator
2 return
3 feed
4 thermostat
5 water pump
6 right cylinder head flow
7 left cylinder head flow
8 connecting pipe and return
9 expansion tank
10 heater cooler
11 aux water pump

[cirrusblau]

Your routing is correct. That's how I did mine before. Could be more trapped air.

[theBMWbeast]

The answer, for posterity’s sake, is that my 6 month old, working perfectly fine, Wahler thermostat went kaput at the exact same time as this happened. I think maybe the slight overheating broke down whatever is inside the thermostat? New OEM replacement, no problems.