DIY: 2005 XC90 Heater Core Replacement Topic is solved

[xHeart]

Quick question: Did you bother draining the coolant from the radiator before you removed the old heater core? Or did you just top up the coolant at the end? Not sure what the best approach is!

Trying to replace the Heater core on my freezing 2008 XC90 very soon!

Heater core does not retain coolant; it circulates. There will be some in the pipes and passage - catch it with a towel at disconnect.

Install with NEW Volvo clips.

[vtl]

Heater core does not retain coolant; it circulates. There will be some in the pipes and passage - catch it with a towel at disconnect.

Remove the heat core hoses on the other side of the firewall, blow some air into one tube and collect coolant from another. Then the core will be almost bone dry. I used a shop vac in reverse as a source of air.

[cn90]

Update on photo from the web...

Sometimes, it is difficult to understand this crowded space and contortionist position necessary to perform
repair, I downloaded a random photo fron eBay and labeled it so you can see the layout...

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HC-S60.jpg (146.23 KiB) Viewed 1000 times

[ogatrulle]

cn90, thanks for an awesome writeup. I referred to it again today while I replaced the heater core on my 06 v70 2.5T. Space under the dash was cramped and it was hard to get leverage. Took me six hours and several hundred swear words.

I did this job on my 08 xc90 about two years ago (same heater core part). The v70 was harder due to limited space.

1. I got a new Nissens HC, new volvo o-rings, and new volvo clips. Behr seemed to be NLA.
   
   One thing I liked about the Nissens was that the top and bottom edges are made of flat stock instead of exposed fins, so sliding it into its slot at a slight angles doesn't bend a bunch of fins.
2. I set up a piece of plywood maybe 1-2 feet wide and about four feet long immediately behind the open driver's door. The inboard edge rested on the lip of the door opening, and the outboard edge rested on a plastic milk crate filled with bricks.
3. After detaching the heater hoses in the engine compartment at the firewall, I removed two bolts from the firewall heater hose plate and took it and its gasket out so that the aluminum pipes would have greater freedom of movement.
4. I also cut the zip-tie holding the pipes high up under the dash to a white plastic bracket. I was able to reach it with regular diagonal cutters. Doing so was important to being able to move the pipes.
   
   When it came time to pull the heater core, I was able to swing the end of the upper-attaching pipe toward the front of the car just enough to clear the heater core path.
   
   I was able to maneuver the end of the lower-attaching pipe just aft of the heater core's path. Doing so moved the high part of this pipe out of its notch in the high white bracket (where the zip-tie was).
   
   I believe that moving the pipes, instead of bending them, makes it easier to seat them straight in the new heater core.
5. Link to Peppermint's video mentioned earlier:
   
   It has several important details, including:
   - how to remove and install the brake light switch (non-obvious)
   - how to detach the steering coupling and the 30 N-m torque value for the nut
6. I did need to undo the steering coupling, compress it back toward the steering wheel, and swing it up. Doing so made just barely enough room to get the old heater core out and the new one in.
7. There was a fair bit of warning in Peppermint's video and comments about not turning the steering wheel while the steering coupling was detached due to risk of damaging the steering angle sensor.
   
   I tied up my steering wheel so it wouldn't move, but I don't understand the warning, because I thought the steering wheel locked when the key was out. I wasn't going to experiment, but I wonder if someone could comment on this issue.
8. The hardest part for me was getting the clips back in. I almost couldn't find pliers with a combination of wide enough jaws but enough handles that didn't get hung up on the other under-dash items.
   
   I had to leave the lower-attaching pipe out of the way completely while getting the clip for the upper-attaching pipe installed.
9. I idled the car about twenty minutes. Upper radiator hose got hot but I didn't get warm air in the cabin with the temps set all the way up, so I'm guessing there is still air in the system. Kid will drive it tomorrow so I'm hoping cabin heat will start working then.

[cn90]

I am posting this so everyone can see as a baseline measurement.

- 2005 XC90 2.5T with 132K miles.
- "Brand-new" thermostat and heater core (Behr).
- After a hot run (~ 30 miles).
- Car idling on driveway at ~ 700 rpm.
- Heat is off, cabin fan off.
- This is to simulate "natural heat loss" after heater core...
- So the Delta Heat Loss via HC is about 7 C under normal condition.
- Of course when you turn on the heat in the cabin (fan running), more heat will be extracted from the HC.

- Anyway, I am posting this here so ppl can use it to diagnose a bad HC. Under the same condition (same
ambient temp etc), a bad HC will show a bigger delta value.

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[xHeart]

Thank you for your DIY, cn90.
I'll use it this week.

Our 2013A XC90 with 170K miles can use the replacement service.
There is strange smell when the blower is running on heat, unbreathable with windows up. It dissipates with the fan turned off.
Does a failing heater core takes longer to warm up or is it coolant fluid temp that supplies the heat?

What is a good replacement if Behr is not available; is Magneti Marelli an OEM for 3.2 engines?

TIA!

[vtl]

Coolant is poisonous to breathe for prolonged periods.

Bad heater core leaks.

Heat core may become clogged in cars with poor maintenance discipline (no coolant replacement in decade - limestone circulates in the system and clogs small passages in heater core) or stop leak was used.

Nissens has worse than OE/Behr/Mahle heat transfer efficiency. Which is pity, since heating system performance in our 20 y.o. Volvo in negative temps is unbeatable and makes it a dedicated winter driver.

[ogatrulle]

Just another data point on the Nissens: as I reported above, I installed a Nissens six months ago. In our mild Northern CA climate (temps down to freezing at night for a month or two, with thin ice on the windshield), my son, who drives the v70 daily, has not observed any issue with heating effectiveness.

That's a non-engineering, non-scientific datum, and I'm not in a position to dispute instrument measurements of heat transfer, but subjectively, it's been OK for us so far.

[cn90]

Thanks ogatrulle,

Just learned this little trick from another forum as I always struggle with the metal pipes blocking my way
bc I always swing BOTH metal lines to the Front.

As it turns out, another person (in another forum) mentioned that if you swing the UPPER pipe to the FRONT
(of the car), and the LOWER pipe to the REAR, it is a lot easier. This makes sense bc you bend less doing that
simply bc the UPPER pipe is closer the the Front and LOWER pipe closer to the Rear. So, if anyone does it
this way (swing the Lower Pipe to the Rear), please provide feedback.

This is what that person (in another forum) said: Upper Pipe (GREEN) and Lower Pipe (RED). Just use something
to spread the pipes apart...

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HC-S60.jpg (114.91 KiB) Viewed 332 times

[xHeart]

Any thoughts on hose clip and o'ring -- aftermarket vs OE.

TIA