Heater Hose Firewall Coupler Elimination w/pics

[burnout8488]

I, like many, had a cracked heater hose junction at the firewall. This came in a lot cheaper than a new one



The coupler needs to be gutted to make room for the hose clamps that will be housed inside it.



Slide the metal trim plate over the metal hoses, then connect 5/8" heater hose to them and clamp it down. The plastic junction shell needs to be inside the cabin at this point. Screw it in using the T15 Torx screws and the engine bay side is complete.


The aluminum heater pipes need to be cut to make room. I snipped this much off of them:


Cut the hose to the proper lengths in the cabin (total guesswork, it's so cramped), install the pipes onto the heater core, and clamp it down! Worm gear clamps will NOT work here, as there is no room between the gas pedal and the heater hoses. You will need to get some clamps like the ones shown. I stole some off of a family member's Corolla.

Your gas pedal mounting bracket may need to be trimmed if using different clamps. Nothing a Dremel can't solve.



So far it holds pressure and doesn't leak a bit! I have confidence this will last a very long time.

[erikv11]

Nice write-up!!

On my 850 I cut the pipes much shorter on the cabin side, in which case there is room for regular, screw-type hose clamps. I'll try to get a picture and put it in this thread, a good place for it.

[burnout8488]

Never thought of cutting them shorter, that would make it much easier. Definitely post it up!

[kevins s70]

I think i will go this way too - thanks. i just replaced my evaporator and didn't think about replacing the seals for the heater core when i had everything apart. It is really difficult to do now That is the the first io heard of the hose junction cracking.

[burnout8488]

If it ain't broke, don't fix it. My heater hose system only started leaking once I touched it. If your o-rings are fine, they probably will be for a good long time as long as you don't go in and try to disconnect parts of the system. Then things start cracking and you might regret touching it in the first place :p

[erikv11]

On my 850 I cut the pipes much shorter on the cabin side, in which case there is room for regular, screw-type hose clamps. I'll try to get a picture and put it in this thread, a good place for it.

Also, if you do it this way there is no need to modify the couple or the gas pedal at all, just slip the 5/8 hose through the firewall. No Dremel usage.

The hose setup is out of the car now, it was in my parts car and I robbed the heater core for another one. But I will put it into one of my running 850s soon so I kept it. One end of the hose connects to the engine block, the other to the cut off pipes like this:

Coupler bypass, ready to install in an NA 850. About 3/4 inch of hose is on the aluminum pipe.

heater_hose_setup.jpg (161.51 KiB) Viewed 5674 times

I used a heavy duty hose, Gates Green Stripe, which made bending it a little difficult. A lower grade hose would be easier to work with.

use 5/8 heater hose

heater_hose_setup_hose.jpg (255.64 KiB) Viewed 5674 times

[BEJinFbk]

But with the Green Stripe,
you only have to do it once.

[matthew1]

Burnout, this is very good. Scheduled for inclusion in the Repair Database, and your account is now Contributor. If you want the default Contributor avatar, just delete your current.

[MilehighV70XC]

The return line from the heater core is leaking at the block on my car. No matter how tight I get the clamp it still leaks. I plan on running hose from inside of the car to the block and eliminating the junction and the factory hoses. Going a similar route as described in this thread www.matthewsvolvosite.com/forums/viewtopic.php?t=44948&p=265773
After I cut the hard lines in the car, should I flare the ends for a better seal or is it not necessary?
Anybody who has done this, did you run into any problems running it from the heater core directly to the block?

[erikv11]

I did not flare the ends, no leak issues. Overall, no problems with the alteration.

EDIT: I did, however, use a tubing cutter when I did it. Makes nice, clean cuts.