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740 Heater Core Replacement (Pictures)

The Turd

New member
Joined
Nov 9, 2015
Hey everybody! New to the forum. I replaced the heater core in my 91 745 turbo last week, I guess you could say I'm a proper Volvo owner now lol:cool:. Here's some pictures that I took of the process.

Time to remove the core was 3.5 hours. Total time was probably around 12 hours over 3 days because I removed all of the carpets to pressure wash them.

Tools you will need:
7mm and 10mm 1/4 inch sockets
1/4 inch extensions
Universal joints
Socket wrench
10mm wrench
7mm ratcheting wrench (not necessary but very helpful)
Plastic pry bars (for interior pieces)
Philips and Torx drill bits.
Drill + small drill bit
Various screwdrivers
Sealant for heater core box
Hammer
Brass plumbing elbows
Flashlight
Small hands
Small phillips screw (For replacing the rivet)
4 cups of coffee
Cigarettes (optional)

First I bypassed the heater core with some brass plumbing pieces. (and disconnected the battery of course)
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Then I took out the center console
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Then the glove box
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Then the ash tray and center storage/cig lighter assembly
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Stereo and its housing (phillips screw deep in there)
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Now you can remove the center side panels and the kick panels
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Unclip the relay tray and move it to the side
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Remove the heater control panel, make note of wiring and vacuum lines
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Here's where the fun starts. Start removing ducting. Its a fairly strong plastic and can handle twisting and pulling.
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Rear floor vents removed
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Drill out the rivet on the distribution box and remove. Remove rest of floor ducting
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Here's the heater core box. There's about 11 7mm bolts around it
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Box is removed. Getting those bolts out took me about an hour
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Closeup of heater core
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Core is out yay
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Old vs new. Idk why the company painted the new one silver. It's a Spectra brass/copper core ($70 on rock auto)
Volvo%2018_zpsg5cptwt4.jpeg
 
I have the sugary smell in my 1990 740 so it'll be my turn to rip my knuckles off soon! I did a 940 and a 240 in the past so I know what I'm getting into! :nod:
 
I've had the utter pleasure to do 7 of these in the last 18-24 months.

fwiw, if for any reason you pull your dash (replacement, better color, etc), DO THIS regardless whether its officially leaking or not. The last 3 I pulled was for that reason alone and all of them had green streaks on the seams or had started to weep. I'm prepping to swap a gray interior into a 940 in about 2 weeks and will do this again. With the dash out of the way its a 45-60 min job.

Break it on your terms as they will never fail on a sunny 75F day either.

:cool:
 
Nice job on the write-up. Brings back some fond memories of mine... not. The only positive thing I remember about doing that job was discovering some good new music on Pandora playing on the background.
 
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