'97 855 GLT: Notes on changing heater core pipes

[jreed]

After reading here about the good chance of having a leaking heater core and especially about suddenly bursting heater hoses, I decided it would be a good idea to do some preventative maintenance. So I replaced the heater core, heater core pipes and heater hoses which were all original on my 1997 855 GLT at 177K miles. Many others have already written up good descriptions and advice about how to do these jobs and which parts to use including:
Song Huang: viewtopic.php?p=351687
Ben850: viewtopic.php?f=35&t=56550&start=42
cn90: viewtopic.php?t=55794
rspi:
Matthew1: viewtopic.php?f=1&t=40240
Precopster: viewtopic.php?t=40547

I wanted to add detail on how to get the gas pedal out of the way when removing and installing the metal pipes to the heater core. To me there just wasn't enough room between the pedal and the white plastic AC duct to allow removal of the coupler:

Heaterpipe1.jpg (128.36 KiB) Viewed 3546 times

Use a pry bar to pry the head on the pedal hinge pin to the left:

Heaterpipe2.jpg (153.21 KiB) Viewed 3546 times

Pry pin out about 1cm:

Heaterpipe3.jpg (157.12 KiB) Viewed 3546 times

When it is out far enough, the copper leaf spring will push the whole pedal assembly upwards:

Heaterpipe4.jpg (142.44 KiB) Viewed 3546 times

Move the pedal assembly to the side. There should now be enough room to pull the coupler out of the foam 'socket' it is pressed into (be sure the two T25 screws in the engine compartment have already been removed):

Heaterpipe5.jpg (130.22 KiB) Viewed 3546 times

After removing coupler from firewall:

Heaterpipe6.jpg (96.54 KiB) Viewed 3546 times

I found that getting the old coupler out was a lot harder than getting the new one to go back in.

When I was inspecting the old heater core, I found signs of leakage with the biggest being right above the inlet and outlet ports where the aluminum tubes enter into the plastic end caps. There was some green residue visible. I hadn't noticed any drips, or the smell of coolant, or a filmy residue on the inside of the winshield or detected a significant loss of coolant at the reservoir (maybe 100mL-200mL every couple of months).

Leaking core1.jpg (175.32 KiB) Viewed 3546 times

The green residue on the core at higher magnification. It looked like some kind of geologic formation you'd see inside of a cave:

Leaking core2.jpg (100.05 KiB) Viewed 3546 times

The other suggestion I wanted to make was to recommend a pair of hose pliers for removing the old heater hoses from their connections to the engine. I had a nice pair that I got for Christmas this year that worked really well to grip the hose and let me twist it to break the bond and pull it off the fitting.

Hose pliers.jpg (57.16 KiB) Viewed 3546 times

[dosbricks]

Jason, nice documentation of an additional detail. I changed out everything as you did and would have not likely figured out the accelerator release if someone had not mentioned it somewhere in a thread.

I have a gizmo similar to this (wood handle so you know it's old) which is dandy for getting radiator or heater hoses loose.
http://www.ebay.com/itm/Radiator-Hose-R ... ls&vxp=mtr

[jreed]

Thanks!
I've got one of those speed claws too. They are very handy!

[jreed]

I sliced open the old heater core using a hacksaw last night. I took a couple of photos. The first shows the cross-section of the plastic-metal bond at the end cap:

Core crosssection01.jpg (176.07 KiB) Viewed 3522 times

The second one shows the visible signs of coolant that has left a green deposit, presumably after seeping between the plastic and the metal end cap bond.

Core crosssection02.jpg (181.53 KiB) Viewed 3522 times

[Atis]

Great writeup with useful details.
I did the same some months ago and I really missed this info that time.

What was your sequence for putting everything together?
I was thinking about that tightening the screws of the coupler/heatercore/pipes in a wrong sequence can bring extra tension on the Al tubes and the plastic parts.

[jreed]

That's a good question! Thanks for asking!
I placed the new coupler back into the opening in the firewall first. Then I installed the new heater core. Then I tightened the four screws that hold the heater core to the HVAC vent. Next I tightened the screw that holds the aluminum pipes to the heater core.
Then from the engine compartment I reattached the aluminum/rubber plate that covers the opening in the firewall. I tightened these screws up until the amount of protrusion on the coupler looked similar to the original configuration.
Then I attached the new heater hoses to the barbs on the engine using new hose clamps. Then I clipped the hoses into the coupler.

[Atis]

I did exactly the same way as you did.

My fear is that as the screws of the coupler are tightened, it brings a tension on the pipes and on the small plastic "pipes" of the coupler.
I have tried to look for any advice in Vadis, but I did not find anything.

[loveMy850]

Thank you, I went to my education class, / junkyardand figured out the pin on the petal. I'm hoping I won't have to remove the petal. . I'm worried about leaks due to the fact that I have iron pipes ,I'd really like to keep her as originall as possible,sounds silly perhaps.

[loveMy850]

Would you suggest that I just change to aluminum pipes?

[erikv11]

The iron pipes were only used a year or so, Volvo changed them to aluminum and never looked back. I would definitely change to aluminum pipes from the junkyard.