Back of the head coolant hose question

**10Toes** · 12-09-2010, 12:57 PM

Back of block to bottom (lower) heater core.

**monkeytaco** · 12-09-2010, 01:13 PM

Originally posted by nwvb bmw

Back of block to bottom (lower) heater core.

^^^^ This is correct. Otherwise, no heat.

**samiam3356** · 12-09-2010, 01:29 PM

http://www.r3vlimited.com/board/showthread.php?t=191127

Is the valve on the bottom or top? If bottom then that would be correct as the coolant would go through the black first and then into the HC.

**10Toes** · 12-09-2010, 01:34 PM

I'v had it hooked up backwards before last december, you get no heat. Also my temp gauge read just past half and when I switched them to the right way it went to just under half.

**328ijunkie** · 12-09-2010, 01:39 PM

Im not saying im 100% right but im basing my opposition on the fact the heater valve is in the top Hcore hose and it is designed to stop coolant flowing through the Hcore.

What im thinking is coolant on a 24v motor flows from the front of the motor to the back then to the Hcore (hot side) and from the overflow tank and the other side of the HC back to the backside of the thermo housing....

**samiam3356** · 12-09-2010, 01:51 PM

Originally posted by nwvb bmw

I'v had it hooked up backwards before last december, you get no heat. Also my temp gauge read just past half and when I switched them to the right way it went to just under half.

Please be more specific. backwards meaning to the bottom or top?

**monkeytaco** · 12-09-2010, 02:05 PM

This is for my car's heater hose, the valve is on the bottom, that is what controls coolant flow. Therefore the head is outlet and it runs to the heater core inlet which is bottom.

I've looked at a couple other versions (88 325i- my brother's car, 87 325e - another friend's car) and its the same way.

unless the flow is supposed to go into the heater core first, then to the valve, it should go to the bottom. I can't imagine the HC being filled with hot coolant on a summer day, bmw designers wouldn't do that to us would they?

EDIT:

This is another diagram for another heater core, which is inlet on top:

I guess i'm going to look at mine for real and see which is in my car...

**328ijunkie** · 12-09-2010, 02:09 PM

Top Pipe Has the Valve on the later model cars

**samiam3356** · 12-09-2010, 02:51 PM

So it looks like it depends on core you have. And the valve should be getting the hose from thr back of the head. Going to look at mine tonight.

**328ijunkie** · 12-09-2010, 08:52 PM

No more insight from fellow r3vers?

**Dominic49** · 12-09-2010, 08:55 PM

back of head goes to valve

**328ijunkie** · 12-09-2010, 08:58 PM

Thats what i thought....

**monkeytaco** · 12-10-2010, 07:33 AM

I checked out my car last night and I have the back of the head to the top (inlet) hose. The valve for mine looks pretty much exactly like yours.

I also looked at an 86 325 and it had the valve on the bottom... so check your valve when you hook it up to be sure.

**graphikg** · 12-10-2010, 05:16 PM

Damn, didnt think it made a difference. I always thought it as "Spider, Top; Back Bottom" A little neumonical method of mine.

Back of the head coolant hose question