Heater Core Replacement on the 850

FCP Groton often have specials for 850 heater cores (sometimes as little as $70 on eBay)

If you have a small heater core breach, the smell can be overpowering through the vents.

Heater core replacement on the 850 is not a difficult procedure. Once the kickpanels are removed there are four torx screws and some clips at the heater pipe coupling inside the vehicle. Some upside down work in confined spaces with the blood rushing to your head is sure to happen.

The tricky bit is resealing your heater pipes using an old firewall coupling. This is best replaced with a new component.

Some wet & dry sandpaper or fine grade steel wool will come in handy to clean the heater pipe ends, especially if they are made of iron (Volvo switched to aluminium mid 95 to avoid corrosion)

List of parts for a foolproof change:

1) New heater core (OEM part number 9144221)

2) New firewall coupling (OEM part number 3522035)

3) New heater hoses (part numbers vary depending on whether it’s a turbo or not)

4) Some old towels to catch the coolant as it escapes from the core

5) Some petroleum jelly for assisting the removal of the hose coupling (to be smeared on the rubberised flooring and hose coupling for easy pipe entry)

Don’t bother with the URO seal kit. It only includes the heater hose side seal kit, not the heater pipe side and old seal components can remain lodged in the coupling.

I tried the URO seal kit with a coupling that had been removed and internally checked for notches and burrs only to be disappointed by massive leaks. I have taken some photos of the recent install on my wagon which went really well. Hope I’m not jumping the gun here, but it seemed a good opportunity to post these while they were fresh in my mind.

As far as procedure with heater hoses and heater pipes I smeared just a little petroleum jelly on the engine and heater pipe side of the coupling. This greatly assists a smooth entry of all the pipes.

Volvo 850 Heater core replacement