What's the best way to bleed the heater core?

Chris Kouba

Supporter
I've tried a few times to get it to push fluid through with no success. It is approximately level with the expansion tank so gravity is not my friend. It is fed via a tap in the nose section on the hot side of the rad input hose leading back to the core and coming back to the return side of the rad plumbing.

The two short, straight pieces in this pic are the connectors from the hard pipes to the rad:
IMG_4717.JPG


I don't currently have any pics of the complete setup.

I've had the nose high, I've put a clamp on the return hose to try to force the flow through the core, I've used "surplus" revs to apply flow through the system. The only thing I am getting out is cold air as nothing is circulating through the core.

Would it be advisable to vent the system once it's up to pressure? Does anyone route their heater core directly to the water pump like normally configured?

Any suggestions would be appreciated.

Thanks in advance,
Chris
 
Chris

I had the same issue.
My heater picks up on the hot tube going to the radiator and exits on the cold.

I found water was not being forced up to the core.
I have screw in fittings so I indexted the hot fitting and removed it.
Then I soldered a section of short tube to the threaded end that has a 45 cut.
The open end of the cut was pointing up stream, this forced the water up the tube and fixed the issue.
I still get a little of it when the car idles for a long time but I dont see that as an issue

You need to get the in fitting into the water flow, as you have it the water flows past the fitting.
Jim
 
BMW uses an extra water-pump (in some models) in the heater system, I have also such pump in my Hartge Z3 car, see number 2 >>

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Water valve/Water hose BMW 5' E39, 540i (M62)

it starts to operate as soon as you turn on the heater from coldest to warmer/warmest, there is some switch in that regulator.
it helps to get the water pumping around way better.
 

Peter Delaney

GT40s Supporter
Chris - much the same solution as Jim C. Heater input spigot angle at 45deg to the flow to divert into the heater, & 45deg spigot on the downstream pipe to suck from the heater. Not perfect or fast, but it does work ok !

Kind Regards,

Peter D.
 

Chris Kouba

Supporter
I soldered a section of short tube to the threaded end that has a 45 cut. The open end of the cut was pointing up stream, this forced the water up the tube and fixed the issue.

Thanks gents.

I do have a little of this going on. Looking at the two straight pieces, the upper one is for the heater send. I did angle the spigot and stick it into the flow a little. I was worried a bit about impeding flow to the rad and not getting enough cooling at the rad for the motor so I erred on the side of caution. I guess I'll go back at it with more purpose instead.

My temps have been rock steady with mild usage. If I flog it it'll start to climb into the low 200's but even in traffic on warm days it'll stay pretty close to 185°.

Chris
 

Chuck

Supporter
Chris:

I found that the heater will eventually bleed itself after a number of run and cooling cycles. It does take quite a few cycles but is an option to adding a bleed line in a location that is nearly impossible to access.

You will know when it has bled itself because the heater will generate more heat more quickly.

Just another idea.
 
Chris,

This might work...Im not sure, but its worth a try......

On the send. Clamp the rubber hose where it goes into the rad. this will force the water to go in the heater, and force the air out.Then remove the clamp. I have never tried it on a car, but thats what I do when Im bleeding the rads for the central heating system in my house
 
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