Heater hose M50

[jahnaboi]

I really don't know what you guys are talking about. I've pulled heater core valves out of 1986 + e30s all which have the valve on top and all which have the direction of flow towards the front of the car. The only variation of the heater core I believe is in a non a/c car. That's it (from the top of my head). (Could be wrong).

As for the back of the head going to the valve theory, I see no point regardless of which is connected to which. If the flow is restricted (valve closed) regardless of which direction its coming from, hot water would not reach the pipes as the water within the heater pipes/core are stagnant causing an increase in resistance and would force the flow to different areas. So no. The heater core valve is exactly what it is, a valve. Nothing more, nothing less.

But because of the design of the valve itself, I could see the potential hazards associated with connecting the direction of flow inversely. Which is why people have intermittent heat situations with there RPMs higher than idle.

If you know what's good for you connect the back of the head to the bottom heater core aluminum pipe. If you want to make sure then just make sure that you note the direction of flow of your heater core valve.

[dude8383]

That proves nothing. What you have to look at is the heater core and where the valve is. Back of the head feeds the valve which most of the time will be the bottom BUT could be the top.

pardon me, i should have mentioned that its a late model car.

[328ijunkie]

The early models had the valve on the bottom usually guys. Basically every late model ive ever worked on had the valve in the top pipe.

[monkeytaco]

That proves nothing. What you have to look at is the heater core and where the valve is. Back of the head feeds the valve which most of the time will be the bottom BUT could be the top.

This is true^^^

If you have an earlier model you could have the valve on the top. Head always goes to valve.

[samiam3356]

That proves nothing. What you have to look at is the heater core and where the valve is. Back of the head feeds the valve which most of the time will be the bottom BUT could be the top.

[dude8383]

a few pictures might help :)

[MattM]

yup E30 M20 hose is a perfect fit, back of block to bottom of heater core.

i believe its this p#11531289377, but its hard to tell from the diagram

[328ijunkie]

^ This.

[samiam3356]

Some heater cores have the valve on top and you will ALWAYS feed the valve first. Checked with Jlevie on this as well. I thought this way before until finding out some have the valve on top. In that instance the back of the head will actually go to the top not bottom. So you have to check and see what heater core you have before knowing where the hoses will go.

[Fusion]

DOHC wiki

Heater Core Coolant Hoses
The "spider" hose connects to the top heater core pipe out of the firewall in the engine bay.
The coolant hose from the back of the head connects to the bottom heater core pipe out of the firewall in the engine bay.
This step is important, otherwise the heat will not function very well i.e. it gets cold anytime the car is at higher RPMs.

I had mine switched and I didn't have heat when up to speed.
Engine temps were also off.
Make sure this is right because there's pretty much no other way to fix this than to take off the whole intake manifold, lose some coolant and have to rebleed.

[asubimmer]

Just to clear the toss up for what hose is where; The back of the head connects to the bottom hose of the heater hoses. If you look at the direction of flow that is marked on the heater core valve itself, the flow is the direction of the front of the car. So if the direction of flow from the head is towards the rear, it would have to go to the bottom hose. Also I believe the direction of flow would affect the effectiveness of the valve itself.

So bottom line:

- Back of the head goes to bottom heater hose pipe
- Top of heater hose pipe to spider hose.

-Jasper

this!

[jahnaboi]

shows flow direction. And you def want hot water into the top hose on the Hcore. That im 124234234234% sure about.

I know Dom Personally and im not calling him out but im 99% sure this is how its supposed to be done. E30 and E36 motors flow coolant the same direction.

Just to clear the toss up for what hose is where; The back of the head connects to the bottom hose of the heater hoses. If you look at the direction of flow that is marked on the heater core valve itself, the flow is the direction of the front of the car. So if the direction of flow from the head is towards the rear, it would have to go to the bottom hose. Also I believe the direction of flow would affect the effectiveness of the valve itself.

So bottom line:

- Back of the head goes to bottom heater hose pipe
- Top of heater hose pipe to spider hose.

-Jasper

[328ijunkie]

shows flow direction. And you def want hot water into the top hose on the Hcore. That im 124234234234% sure about.

I know Dom Personally and im not calling him out but im 99% sure this is how its supposed to be done. E30 and E36 motors flow coolant the same direction.

[samiam3356]

I thought it was reversed for the x5x swaps though.

The guys that helped me do my swap both have there's the way I said as well. Dom and Justin have done A LOT of these swaps and I trust them over you. Doesn't mean your not right but I will go with their experience.

[328ijunkie]

Customers M20 HG job, the Head hose is disconnected the main spider hose isnt.