Reverse flushing the heater core?

[canada karl]

Which hose is inlet and which is outlet?

[Mike W.]

The opposite of what I thought. Hot should be on top, and cold or return on the bottom. Wrong. I'll spare you the long story, but it is,

Hot or in on the bottom.

[canada karl]

So to reverse flush the heater core I go thru the cold on the top,correct?

[Mike W.]

So to reverse flush the heater core I go thru the cold on the top,correct?

Correct. But if you're really trying to flush it with a hose I'd go back and forth a few times, alternating between top and bottom.

[canada karl]

Thanks Mike

[HB528i]

I don’t think it really matters. We just had this discussion on the e9 Forum. On a CS water enters on top from manifold, on a CSi it enters on bottom, same heater. Some say it enters on top from back of head on a CS, it’s not going to make a difference.

[Mike W.]

I don’t think it really matters. We just had this discussion on the e9 Forum. On a CS water enters on top from manifold, on a CSi it enters on bottom, same heater. Some say it enters on top from back of head on a CS, it’s not going to make a difference.

I don't think E9s had a heater valve, I know E3s did not, and that is the difference. If connected wrong the heater valve can flutter and bypass coolant in an E12.

[HB528i]

Thanks, I assumed no valve in the e12.

[Mike W.]

Thanks, I assumed no valve in the e12.

There is and replacing it has been described as the worst job on the car.

[canada karl]

Yah you need tiny fingers and a tiny wench!

[Mike W.]

Yah you need tiny fingers and a tiny wench!

And to be a contortionist while laying on your back.