Heater Core Removal/Install?

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Heater Core Removal/Install?

Postby TommyG » 29 Nov 2004, 20:36

Hi all,

My 86 acadian just started dripping radiator fluid on my feet. It's also dripping radiator fluid out of the big black box on the firewall that attaches to the dash. There's also white radiator fluid fumes blowing out of my defroster/heater vents.

I'm assuming that my heater core is broken.

I was wondering if anyone who has replaced one could give me a heads up on how to take one out/put one in and how difficult it is?

I believe I have to drain the radiator, remove the two hoses to the black box on the firewall (not sure of the proper name for this box) and then take off the box. It looks like just a bunch of screws that I need to remove? If I remove it will fluid spill all over the place?

Then it's just a matter of putting in a new heater core and putting everything back together.

Does this sound correct? I don't need to remove any dashboard stuff, do I?

Approximately how long should I expect this to take (ie if I have to compare the time to a repair shop estimate).

Thanks alot!

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Postby Crum B » 29 Nov 2004, 20:50

It isn't a huge job taking it out and i would say drain the fluid out of the system first but i'm not sure what its like to put a new one in (i only ever took one out for race car)but it shouldn't be too hard. 8)
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Postby Doive » 29 Nov 2004, 23:05

If your car is set up anything like the british chevettes, that black box will contain your heater fan with the matrix located underneath it. When draining the system ensure the heater controls in the car are set to hot to allow fluid to drain from the matrix. I've never swapped one, so I don't know the exact removal/refitting procedure, but I always find the best way is to start taking stuff apart, I always learn as I go along, especially from the mistakes! Maybe best to check a manual if your not a loony like me.
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Postby TommyG » 03 Dec 2004, 19:19

Well, I had it fixed at the local midas. It was the heater core that failed, and it probably wasn't that hard to do. I could likely have done it myself but with only the one car, when I screw it up we're out of luck!

Thanks for the help.
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Postby Chevette Girl » 17 Jul 2005, 18:02

Dangit, wish I'd seen this when the info would've been useful to you... I must have changed heater cores 5 or 6 times on my various Chevettes... $50 part if you do it yourself, $150 if you get someone else to do it, if I recall correctly...

You need a basic tool kit (you should be able to manage with a socket set with screwdriver attachments), a new heater core (I had a radiator place fix one for me once), a pan to catch coolant, something to absorb or wash away spilled coolant (it IS highly toxic and very temptingly sweet) and some new coolant. Having access to running water is a good idea (garden hose). You might want a packet of plumbing putty ($3 at Home Depot) to seal things back up, but I've never bothered (see step 8 ).

1) undo all the screws around the black box on the firewall (some are a pain to get to, I usually don't replace the two nastiest ones when I put it all back together), they're all the size of the hex head slot that takes different screwdriver bits (1/4" or therebouts). If there's sealant around it, try not to destroy it. You shouldn't need to disconnect the fan, but you might need to pop off the little wire that's attached to the middle (it goes to the hot-cold slider on the console).

*note to Doive, FYI - the black box from North American Chevettes has the fan on the passenger side, the heater core on the driver's side, and the middle is the temperature damper attached to the hot-cold controls on the console*

2) put a pan under the part of the firewall where the two hoses come in from the engine (driver's side). Park so that the heater core is uphill fron the rad if possible, to minimixe coolant loss since this is the quick and dirty version where we don't drain the system.

3) (assuming the car is cold), Undo the rad cap to make sure the system's not pressureized (although if it's dribbling on your toes, it's probably not a concern) then undo the hose clamps that attach to the heater core, wiggle the hoses off, and try to get the green stuff to go in the pan instead of all over the engine compartment. You might need to use a screwdriver to loosen the hose if it's been on there a while, or a pair of pliers to twist the hoses off, try not to damage the hoses, they're cheap to replace ($8 for enough to do three Chevettes) but not when you can't drive the hardware store because your car's in pieces in the driveway. Remove the heater core, there's a little clamp that's the same size as the screws that hold the black box onto the firewall, and a keeper to slide off the other side. Empty it into the pan.

4) Clean all the coolant out of the inside of the black box: make sure you thoroughly rinse and carefully dry the fuzz attached to the damper in the middle of the black box, failure to do so may result in disintegration of said fuzz, which may result in your fan spitting black bits of fuzz at you and the heater blowing on your toes even when the heat's set to cold/vent (or at least I'm pretty sure that's why three of my Chevettes have done this).

5) Use the garden hose to make sure water flows through your new heater core, it also makes sure rinses our any crud that might be in it. This can be done (carefully!) at a sink indoors if you're without a hose. Empty the water out of the heater core.

6) Install the heater core into the black box, making sure to secure it properly.

7) Attach the hoses on to the new heater core, one's bigger than the other so it shouldn't be hard to figure out what goes where. Tighten the hose clamps good and tight, but not enough to crush the heater core pipes or split the hose.

8 ) Reinstall the black box, if there's any sealant, try to keep it intact so you don't get rain leaking down in there. If you're really concerned about rain leaking in, try using the rope putty you'd use for plumbing - looks like plasticene and is pretty cheap). You can always take the black box off and put the putty in later, that'd be a 5-minute job as long as you leave the nasty screws out). If you disconnected the heat controls and the fan, put them back in.

9) Replace the rad cap and give your radiator hoses a squeeze (this will move the coolant around a bit. If you parked on an incline, start the car up and turn it around so the rad's the highest point. Sometimes squeezing the rad hoses will do it, sometimes jumping on the bumper helps, sometimes you just have to drive it to get the air out of the system. Either way, jiggle it around a bit then pop the rad cap off again to see if it needs topping up, pour coolant right into the radiator if it's low, otherwise put an extra litre or so of coolant in the overflow tank. I wouldn't worry about diluting it at this point, you're not adding that much to the overall system. Don't forget to replace the rad cap, and don't open it if the car is warm!

10) After you've started it and let it run a few minutes and check for leaks at the hoses. If not, let it run (should be safe enough to actually drive at this point) long enough for the thermostat to open (when the heat comes on in the inside) and check again, and then check the overflow tank when it's cooled off again.

11) make sure to clean up and dispose of all traces of antifreeze from your work area. Some places will "take it back"

Ta-daa, no more broken car. And if I can do it several times without major incident, anyone can.

If your Chevette already blows hot air on your toes when it's supposed to be on cold/vent, best trick I ever found was to get the pan under the car, undo the heater core, and replace it with a plastic plumbing "L" - about $.89 at Home Depot - for the summer. This is also a useful trick when you want to try to get your heater core repaired - pop it out, clean things out, put the black box back, and install the plumbing "L" to connect the two heater hoses, put the box back, drive off to the radiator place and see if they'll fix the heater core....

<sigh> Hope this helps the next North American heater core problem...

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