The OFFICIAL heater core hose thread/answer

[328ijunkie]

Just realoem a stock M20 rear hose. Or email me and ill do it for you ;0

[328ijunkie]

Bump for people still messing this up ;)

[JinormusJ]

You bumped this just in time
In the middle of fixing the heater core and reverting the bypass the PO did on my car.. This question was bugging me for the longest time

[Jand3rson]

Bump for people still messing this up ;)

I checked it again last winter while I had my motor out for some work/headers. So glad it was there. :D

[CirrusblauS52]

Bump. This may be the reason my heater isn't getting very hot. If it isn't I'm out of reasons - already installed a new thermostat, h core, and valve.

[wilholl]

Bump. This may be the reason my heater isn't getting very hot. If it isn't I'm out of reasons - already installed a new thermostat, h core, and valve.

or Air

[CirrusblauS52]

Well, the hoses have been swapped and now the heater works great! Super happy!

[328ijunkie]

Glad to hear!

[TeXJ]

Have a question on my heating issue:

1990 325IS, m52b28 swapped car.
Heat works fine...then it starts to get cooler until there is no heat. This could take 5 mins to 10 mins. Not sure if it is related to speed, the higher the speed the quicker the heating starts to get cooler.

Anyway, so the heat will go to just blowing coldish air. I can fix this by turning off and turning the car back on, and immediately after turning the car back on, hot air is once again flowing.

Any ideas on what this could be? I've been searching but not sure if what I'm seeing is related to what I have.

[pazi88]

Have a question on my heating issue:

1990 325IS, m52b28 swapped car.
Heat works fine...then it starts to get cooler until there is no heat. This could take 5 mins to 10 mins. Not sure if it is related to speed, the higher the speed the quicker the heating starts to get cooler.

Anyway, so the heat will go to just blowing coldish air. I can fix this by turning off and turning the car back on, and immediately after turning the car back on, hot air is once again flowing.

Any ideas on what this could be? I've been searching but not sure if what I'm seeing is related to what I have.

You probaply have heater core hoses mixed. The hose from head goes to lower port on heater core.

[TeXJ]

You probaply have heater core hoses mixed. The hose from head goes to lower port on heater core.

I'll check that out, hopefully I can take a look at work here.

[Xelo]

Hi guys,

So I made this. Hope clears things up as I've recently encountered this problem and did some digging.

[Chebyshev]

I know this is a super old thread, but I'm having a little trouble with heat right now (no heat at idle, heat when revs are higher). I was poking around the heater core pipes in the engine bay - the bottom one comes from the block and gets hot at idle, but it has a valve or something in it before it goes through the firewall. It isn't a straight tube. Any idea what that might be?

Just realized this is in a 24v swap forum. My car is M20, but that shouldn't really change things.

[r1lukasz]

Found this old thread maybe I could get some help, e30 with a m52b28 heater only works on idle , when I rev it a little or start driving it’s starts to blow cold air and while on idle Im getting hot air, I checked the hoses from heater and the bottom is going to the head, is that how it’s correct?