I know some will not agree with this, and I respect that some engineer, somewhere, had some reason for the elaborated system of hose - metal fitting - O-ring - junction - O-ring/plastic ring/O-ring - metal tubing - O-ring - heater core, but after buying the kit with the four O-rings, two plastic rings, and two connectors and being unable to make them work (connectors would not fit into the junction like the factory connectors), then seeing that I might need a new junction AND outside hoses too, I decided to take matters into my own hands. I bought me 10 feet of good quality heater hose (although it didn't take that much), cut the metal lines that come directly out of the heater core connection (close to their ends and with a tubing cutter), and ran heater hose from those metal lines, through the old junction (rodded out clean) and directly to the connections on the block and the back water pipe of the engine. I clamped everything together good, and it has worked like a charm with no leaks at all, and no headaches about one of the umpteen O-rings not making a good seal. I just wanted to let everyone else who has felt frustration about this know it is possible.





Here is the inside connection. I cut the metal lines about 3/4" longer than what you see, it's just clamped inside the
hose. I naturally had to use the factory connection / metal lines with O-rings to join to the heater core.







And here is the outside. I removed the "guts" from the old junction and used it, protecting the hose with pieces of split
hose at the firewall. One section did not cover all the way around so Im going to put more later. The ends of the hose
were just clamped where the factory ones were, at the block and back water pipe.



Thanks!

 

hopefully you grommetted the hoses where they come through the firewall.

 

... with a piece of the same hose, split down the middle and wrapped around the hose where it goes through the old junction (bored out clean), although I thought of shooting expanding foam insulation in there ... and still may do that instead. I'm pretty proud of it.

 

expanding foam isnt good for everything and would not spray in int there... It does burn if exposed to heat, and it wont do anything.

 

Pictures have now been added to the original post at the top.

 

1/2" Hose? I thought it was 5/8"....?

 

I think you're right and I may go back with 5/8" one day lol (definitely will if I have to get back in there to replace the heater core again down the line).

I bought the 1/2" because it is what fit nicely on the "cut" ends of the metal lines for the heater core when I was in the parts store. But it was a royal pain to get onto the block and water pipe in the engine well. I had to dip the ends in some near-boiling soapy water but they went on (nice and tight even before clamping).

 

And the reason was to make it easy to put together on the assembly line.

I'm replacing the heater core on my GF's 850, and when I saw all those plastic parts I started thinking the same thing as you. And when the plastic junction at the firewall broke WAY too easily, I was convinced. I'm doing the same setup. BTW, 5/8" hose works fine.
Good idea, and very nice writeup. Thanks!

 

I like your thought process. Great Job, good solution and work around.

 

I agre. the K.I.S.S. is always the way I go on repairs. why screw with a bunch of plastic fittings when you dont have to. having 2 fittings instead of one increases your chance of leaking by a factor of 2, 3 by a factor 8, and 4 by a factor of 64. Just not worth it.

 

Very nicely done indeed.


JPN

 

I did this same repair today. Awesome stuff!!

After my heater core started leaking (and made a terrible mess inside the car that i'll be dealing with for years I'm sure) I broke the metal hoses off where it connects to the interior-side of the firewall junction. I was worried I was dealing with a complicated, frustrating, and expensive (volvo parts), 2nd repair now... thank God I found this thread.

Took out the engine-side hoses (those quick release connectors are a pain if they haven't been touched in 16+ years), removed the metal plate, and then slipped the whole black box out from the inside (had to depress the gas pedal a bit while twisting and working it out underneath). Once out, I was able to remove both sides of the moveable junction points... which leaves a nice channel for the 5/8" heater hose i'm replacing it all with. You'll want to retain the black box now with all the plastic pieces removed from the middle of the 2 holes. Reinsert it, with the plate (and the two small torx screws) and tighten it all up. Love the design of this piece. So simple, yet so effective. Get it nice and straight. I noticed that when I tightened it up, the interior black piece would stick out, providing a nice layer of molded plastic around where the hose will be sitting. I didn't use any grommet, I feel confident in this plastic protecting the hose.

On the metal tubes that go from the heater core up to this firewall junction.... I used a 4" grinder to cut just beneath the metal bracket leaving about 4-4.5" of the original tubes (heater core side is the important piece, make sure you have 2 fresh o-rings... the old ones get completely distorted, and then you start with the o-rings on the tubes themselves, insert and then use the single torx screw to pull it all in).

I clamped the heater hose to the end just like the original poster did, ran it through the firewall channel, and then... I was up against the challenge... which of the 2 sides of the heater core goes to which of the 2 connections on the engine????

Did I think to write it down when I broke it off and starting taking it all out to get it cleaned and figured out? Nope.

There are no flow indicators anywhere, except on the junction covers (which are trash now) on the interior-side... write it down, if you think to, before you tear it out.

My buddy, an engineer, and I tried to decipher what was going on with the cooling system, the heater core, and which hose goes to which... we found a great diagram by google'ing "Volvo 850 coolant flow diagram"...

Basically... when the heater core is replaced, and mounted in the box, as it should be....

The PASSENGER SIDE port on the heater core itself goes to the REAR-(lower) coolant port on the engine itself. It's connecting on the port that is close to a T in the line with a large hose going to radiator.

The DRIVER SIDE port on the heater core goes UP AND INSIDE... below the cam shaft almost... a little trickier.

What is interesting though... when you use the heater hose method like this, you have to be sure to leave yourself a pretty decent amount of curve to the hose, otherwise, you create a kink in the line... not a good thing. I'd be interested to see how others went about this. I thought of several different options (gotta love hose clamps).

I thought about putting a small valve in between these hose connections, before the firewall (just using some more hose clamps and inserting small valves)... so that in the event of further trouble, I could simply turn them and stop the flow of coolant... the mess of this job is the worst. And coolant ain't exactly cheap.

I replaced my thermostat and did a coolant flush during the 2 days I had it bypassing the heater core... that way I know it's clean coolant that is introduced to the brand new heater core.

By the way, to BYPASS THE HEATER CORE, you simply cut the longer of the two original hoses down, and connect it directly to the other coolant port in the rear (which is the one that you'd hook up to the passenger-side port on the heater core)... not going through the firewall at all anymore... and it'll run like a charm, just no heat in your car. :-(

Remember to top off the coolant before you start her up. If you're quick on all the hose swaps, you might not lose a whole lot. I'd recommend bypassing the heater core before you remove anything. That way the feed to your coolant is cut off... and it's A LOT LESS messy overall.

Well... hope those extra details help someone someday. I know I could have used some advice on what hose went where. The flow of the coolant... is kind of something you don't learn until you run into things like this. I have a general idea... but i'm still pretty clueless.

Saved probably $600 by doing all this myself. Not difficult at all... just messy.

 

so with the nicely done write up and explanations
which heater cores to go with. is my question

 

Sorry you struggled with where the hoses go. I actually wrote a tutorial or diagram of the coolant flow when someone else asked me about it on here. See how my name on the site and handle here are the same backwards (Tracy and ycart)?

 

I replaced a heater core with a guy the other day and we did not even mess with those lines that goes up to the firewall. There is a screw at the base of those lines, at the bottom of the heater core. I believe it was a T-25 and wasn't hard to reach. Once the screw was out we pulled the lines/bracket out of the bottom of the core. Really easy.

 

I just did this, but I didn't cut the lines from the heater core to the coupler. I simply used a 5" piece of heater hose and connected it with a hose clamps on both sides. So what I did is totally reversable (without buying new connection pipes) if someone wants to replace the coupler down the road. I only had to do this on one of the lines through the firewall that I must have broken when removing the line from the firewall. I removed the guts out of the coupler hole first and the 5/8" line fits perfectly through the hole.

 

To help make bends tighter and more secure so you don't have to check them later to see if they kinked or wait until you have no heat, you can splice in a plastic elbow they come in 1/2, 5/8 and 3/4 at an auto parts store.
There are also bendable springs (shaping coils) that slip over the hose and keep it bent to shape and from kinking also available at an auto parts store.
These are made by Gates.

 

How long does it take for these to usually break? i am on about 125 130k miles on my 94 850 turbo. And i do not want this to be me breaking down spewing coolant everywhere, so i was wondering how long the fitting last before this happens???

 

It appears that they last about 10 to 12 years. Some of the poorly manufactured replacement cores can fail within 3 years.

Most cars have had them replaced already. The first sign is the coolant odor. They usually leak a little while before failure.

As for the connectors, it's rare for them to fail and come apart, that usually happens when people are messing with them replacing the hoses or something.

 

Digging up an old thread, I know...but im pretty sure that my leak I posted about earlier in the week is my heater hose lines from the block to the firewall. Not sure which one, but I think I may just bite the bullet and do the "straight hose from heater core to block" mod. For those that have done it, are you having any issues with it? It'd be good to know before I go and do it - I don't want to have to do this again in 2 months because a hose rubbed through. Thanks!