Volvo 850 replace firewall plastic union 3522035 with hose—anybody?

Post by **JimBee** » 24 Jun 2023, 10:16

I'm considering taking out the plastic junction-o-ring assembly and just run some 5/8" hose off the aluminum tubes through the firewall. Maybe use some non-hardening Permatex sealant then cinch them with band clamps. The hoses can be installed and clamped on the floorboard or workbench, then just run through the firewall and trimmed and fitted with necessary 5/8" 45 or 90 degree double barb fittings and short lengths of hose to complete the fun.

I'll leave the exterior cover plate in place and seal around the hoses on the engine side with plumbers putty.

Any suggestions?

Post by **rguzz** » 24 Jun 2023, 13:21

Search in database "Heater Core Hoses Fix". One of several comprehensive write ups around.

Post by **abscate** » 24 Jun 2023, 14:13

… after all that research get part

3522035

From FCP , $60 shipped

Post by **Sveedy** » 24 Jun 2023, 14:56

I did away with the inner plastic / o-ring contraption, kept the outer part and the seal, and just attached a set of IPD silicone hoses to the aluminum tubes with hose clamps. Haven't had any issues.

Post by **JimBee** » 24 Jun 2023, 17:09

Got it. Curiously, the search on MVS didn't find it, but Google found in on MVS. Maybe just needed the hyphens.
Here it is;
https://www.matthewsvolvosite.com/heater-core-fix/
Nice writeup and pics. Some fussy work, but not very technical and probably less prone to problems than the OEM.

QUESTION: Why not use the full length aluminum tubes, just slide the hoses on to the ridge, maybe with a little sealant, and clamp them.
Then just feed the new hoses through the gutted housing. Am I missing something? I can see how trimming off the flanges on the engine side provides a bit more room for reconnecting.

Comment? I've seen soft, flexible preformed heater hoses at Advance Auto, which I'd thought of using. Some have non-kinked bends and could be cut to fit. Any thoughts about that?

Post by **Sveedy** » 24 Jun 2023, 17:37

JimBee wrote: 24 Jun 2023, 17:09
QUESTION: Why not use the full length aluminum tubes, just slide the hoses on to the ridge, maybe with a little sealant, and clamp them.
Then just feed the new hoses through the gutted housing.

That's what I did.

Post by **erikv11** » 24 Jun 2023, 18:22

As mentioned in OP's post from a month ago (viewtopic.php?t=102225):

I ran hoses to the pipes for a few years (viewtopic.php?t=46253), has pros and cons, but finally went back to the coupler. Some additional comments in viewtopic.php?t=98579.

If you do it I'd recommend use a heavy-duty hose, the soft kind os more likely to collapse.

Post by **JimBee** » 24 Jun 2023, 18:50

erikv11 wrote: 24 Jun 2023, 18:22 As mentioned in OP's post from a month ago (viewtopic.php?t=102225):

I ran hoses to the pipes for a few years (viewtopic.php?t=46253), has pros and cons, but finally went back to the coupler. Some additional comments in viewtopic.php?t=98579.

If you do it I'd recommend use a heavy-duty hose, the soft kind os more likely to collapse.

Thanks for the tip!

Post by **wizechatmgr** » 29 Jun 2023, 09:36

They used to make stainless springs you could install on the ID of the hoses to keep them from collapsing in bends - we used them in agriculture all the time.

WhatAmIDoing · Post by **WhatAmIDoing** » 29 Jun 2023, 12:16

+1 on the springs, but I had trouble sourcing the correct ones locally. I just replaced the broken coupler in my V70 with straight through heater hoses. Which reminds me I still need to make a gasket for the hole.

I cut the metal pipes back to the core to make swapping out a new core easier next time.

The one heater hose is an easy run without any crazy bends, but the other will require a near 90 degree bend to work.

Personally, I think the best way is to replace the coupler section with heater hose, then at the junctions use 90 deg fittings, and replace the hoses to the engine with the silicone heater hose kit from do88.