Bypassing heater core

mistercrunch · Post by **mistercrunch** » 24 Jan 2009, 04:16

My 850's heater core leaks into the passenger footwell.

I need to get it replaced, but I also need to drive the car. Can I bypass the pipes leading into the core? Someone I spoke to mentioned something about messing up the ECU?

I would probably do the bypass in the engine bay. Does anyone know the internal diameter of these radiator hoses, from the engine going to the firewall? I'll then just join the two pipes on the engine block.

Thanks!!

Post by **MadeInJapan** » 24 Jan 2009, 06:02

I believe there's a special connection at the block and you're going to be stumped trying to figure out how to join the two outlets. It would be much easier to join the two hoses that connect through the firewall. The diagram below shows you how they pull out of the firewall:

: heater core hose ends.jpg (61 KiB) Viewed 674 times

Post by **Ozark Lee** » 24 Jan 2009, 06:14

They are just a barb nipple fitting at the block but I am unsure of the hose size. 3/4" comes to mind but I am unsure. If you drain some coolant and the remove one and carry it into the the auto parts store they can match it up.

...Lee

mistercrunch · Post by **mistercrunch** » 24 Jan 2009, 07:03

Thanks guys...

Not sure what you mean by a "barb nipple". The clamps on the block are the type where, as you screw in the bolt, the whole things consticts around the pipe. Is this a barb nipple?

Got some 19mm hosing (+- 3/4"). Works like a charm!

Now to get the heater core fixed. Luckily it's summer for a few months still

Post by **MadeInJapan** » 24 Jan 2009, 07:05

Glad you figured it out.

mistercrunch wrote:Not sure what you mean by a "barb nipple". The clamps on the block are the type where, as you screw in the bolt, the whole things consticts around the pipe. Is this a barb nipple?

Sounds like a flange screw- but I'm not sure- I've never looked at that connection myself.

mistercrunch, could you take some pictures of what/how you did this. This would be very valuable to our community and to those who need an emergency fix while they wait for a new heater core.

Post by **Ozark Lee** » 24 Jan 2009, 07:52

This is what I meant by a Barb Nipple.

http://www.hindustanbrass.com/hosebarb_fittings.htm

They just use a hose clamp to secure them.

...Lee

rbtyndall · Post by **rbtyndall** » 24 Jan 2009, 10:15

MadeInJapan wrote:I believe there's a special connection at the block and you're going to be stumped trying to figure out how to join the two outlets. It would be much easier to join the two hoses that connect through the firewall. The diagram below shows you how they pull out of the firewall:
heater core hose ends.jpg

Very cheap fix for the above illustration. Should be a couple of inches of appropriate hose (3/4" from above notes) and a couple of hose clamps. The water pressure is on the low end, so if this is a temporary deal, just get the ends of the hose connected together. The water goes to the heater core in a bypass fashion, so if the hose kinks, it shouldn't be a huge deal.

I just replaced my heater core, and it only took about an hour. You can get a little extra work done in the meantime though, if you can handle driving around without lower dash panels and kick pans. Maybe get your old heater core out in prep for the new one.

Hint. When taking out the old heater core, blow compressed air through the firewall to get the coolant out of the heater core.