1997 Volvo 850 GLT Coolant Question

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New heater core - Behr is fine, the one from Lithuania is fine too as long as you clean it thoroughly.
New Orings on both the core and the bulkhead - if you don't get Volvo, match them to the old ones for diameter and thickness
clean up the metal hoses with cloth - the Oring does the sealing

Test for leaks with just clean water.

[1997volvo850]

Those hoses are really high quality and rarely fail. Replace every oring on both the bulkhead and the heater core connect with genuine Volvo parts and you should be fine.

https://www.fcpeuro.com/products/volvo- ... -3545662oe

I initially took your instructions above as replacing the o-rings on the hoses at the heater core (come with Behr heater core) and at the coupler where the inside coolant pipes attach to the coupler on firewall (o-ring kit). The Volvo o-ring kit you cite above looks like it is used for both the cabin connections and those from the engine compartment to the coupler. Were you recommending replacing o-ring on both sides of coupler? I don't believe it is necessary to do the engine side of coupler right now but I want to double check. I'm hoping the coupler is still strong enough after twenty years to survive changing the inside o-rings. There are no leaks on either side of coupler so my goal is not to extend my scope of repairs.

Actually the entire junction box costs a little more than the o-ring kit and appears to include clamps/o-rings for all four connections to coupler/junction. O-ring kit looks like it contains one set of clamps/o-rings.

Thanks in advance.

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My rule is I replace any oring that I disturb, but that’s a conservative approach. The engine side coupling will just seep a bit of coolant if they leak into the engine compartment. The core side leak into the interior which makes an awful mess to cleanup

The mechanics of the coupler really don’t break or wear. I did have to reuse my old clips as the new ones were too deep or perhaps I didn’t quite understand the figment correctly. I put pictures in my thread on heater core and AC refurb....here

viewtopic.php?f=1&t=56005&start=30

Picture of clip issue

[1997volvo850]

Thanks. I bet they redesigned/improved the clips in conjunction with the new coupler/junction box. I'm planning to order the Behr heater core and the complete junction box (with o-rings for four connections instead of one per o-ring kit). I'll use the o-rings and have the junction box and extra clips/o-rings if I need them.

I love your A/C thread. My A/C also needs an overhaul. Is there a convenient time I can drop my car off at your place? :^)

Thanks for all the help.

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Thanks. I bet they redesigned/improved the clips in conjunction with the new coupler/junction box. I'm planning to order the Behr heater core and the complete junction box (with o-rings for four connections instead of one per o-ring kit). I'll use the o-rings and have the junction box and extra clips/o-rings if I need them.

I love your A/C thread. My A/C also needs an overhaul. Is there a convenient time I can drop my car off at your place? :^)

Thanks for all the help.

Im happy to teach people to fish. My 99 lives in Albany NY area and in Ithaca in the Fall, I do Rochester and Buffalo often too.

In NYC Im usually on the Turbo Amtrak

[1997volvo850]

My new heater core arrived. Unfortunately after looking at the Nissens heater core page (with o-rings) it stuck in my head that the o-rings naturally come with the heater core. Not with the more expensive Behr core. Pains me to pay FCP more for shipping than the o-rings actually cost but may need to order o-rings for heater core tomorrow unless I'm able to source them locally.

In the meantime, given how difficult it was getting old heater core out, I thought I'd practice reinstalling the old heater core. Fail. I was not able to get the heater core up inside the housing. The gear cable seemed to be in the perfect spot to block the two heater core ports from getting past. Not much clearance and nothing was smooth so I'm clearly doing something wrong.

This is one of those thirty minute jobs that only take four hours or so the first time. My initial install test resulted in a lot of bent fins on the driver side of the old heater core. I don't recall hearing the crunching fins in the videos.

I've watched several videos and instructors made it sound like the core/holder slides right in (though I'm not sure I saw video of the actual sliding into place). I'm going back to check whether the actual sliding into place is in video.

I'm wondering if not tightening heater core to support housing would make job any easier.

I'm going to go and stare at situation to see if a 'trick' becomes obvious. Maybe I need to start with the side towards the shifter higher than where it ends up.

Any help is appreciated.

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You’ve got Harborvfreight in SYR and maybe in ITH now? You can get a kit of HNBR orings cheap

It is a bit of Tetris to get the core in. I think you have to load it into base first too, then install into the climate system.

[abscate]

You can also reuse your orings and run water only for a few weeks if you promise to drive at 55 and be aware

Then swap them out when you and I do that AC evap core

[1997volvo850]

I'll stop by HF tomorrow. HF HNBR kit has eighteen sizes. I'm looking around web for o-ring size specification for heater core o-rings. I expect snug but not too tight is good enough. Or is it better to use closest fit to o-ring slot in heater core inlet/outlet? I believe seal occurs when heater core is screwed into bracket on pipes so not sure about importance of o-ring snugness to pipe. Current o-rings look like they are on tight and square shaped. I'll also have old one to compare to in terms of overall thickness. Thanks for the HF pointer.

Most instructions indicate to install heater core in support and tighten bolts. Then wiggle into place. I'll try again tomorrow morning.

[1997volvo850]

You can also reuse your orings and run water only for a few weeks if you promise to drive at 55 and be aware

Then swap them out when you and I do that AC evap core

After all the 'you must install new o-rings' warnings from everyone I'm terrified to 'reuse' o-rings. Are the HF o-rings good? I'm not planning to close up the driver/passenger side until I'm sure there are no leaks. I'll likely watch it for at least a week or two.

You have me thinking about the AC evaporator core. I suspect there may be a lot more wrong with AC after not working for five years. I'll have to look up how to diagnose AC failure. I suspect core is #1 AC problem.

Since other family members drove the car the week before I discovered the "no coolant" heater core failure I need to make sure the head is mostly intact before doing anything with AC. I can't afford $1500 head rebuild. I had planned to hook the coolant warning light up to a smoke/flame/siren generator on the hood so my family members would be aware there is a problem. My bad for not getting around to the supplemental warning system.