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tech writeup- 89-94 heater core replacement

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86K views 20 replies 15 participants last post by  shanek  
#1 ·
i don't know how much demand there is for this, but i decided to do it anyway. i took some pics along the way when i replaced my heater core. maybe they'll help some people. i had done the heater core on my supra, so this was actually easier.
keep in mind that my truck has no A/C. :)
click the pics for larger versions:
the full dash before i started. (a bit dirty, heh)

full dash view from passenger's side:

pull the glove box out:

pull out the small piece under the stereo:

pull out the section under the steering column. detach the hood popping cable, and pull out the vent that goes to the upper left vent.

pull the surround for the stereo/climate control. remember to pull the knobs off the climate control, otherwise when you pull it off, they'll fly everywhere!

pull out the stereo:

pull out the instrument cluster:

pull the four (14mm?) bolts holding the steering column up to the main dash support. (the huge metal bar) let the steering wheel drop down onto the driver's seat.

pop the dash out. (make sure you drop the steering column first!)

here's what the steering column looks like dropped out:

remove the bolts/nuts for the two supports for the stereo area, then remove the two fasteners from the passenger's side of the large support bar, and the two bolts/two nuts, and pull it out through the passenger side door.

another of the bar removed:

duct between the blower motor and heater core removed:

i didn't get pictures of having the actual core out, as my hands were quite greasy from helping my friend put rotors, calipers and pads on his '91. so here's the new core installed with new weather stripping from the local hardware store. i also got a new gasket for the extension pipe for the core, and a new clip just for good measure.

and here's the finished product, with everything back in and functioning properly. :) install is the reverse of removal.


hope that helps someone!
-shaeff
 
#3 ·
yeah, after i did it on my supra, this was a breeze. there are WAY fewer wires behind the dash of the pickup!

thanks. :)

-shaeff
 
#7 ·
Milton- i forget where i purchased them, i'll check the name stamped on them. they weren't cheap. they're form fitted plastic with a diamond plate pattern on them. really durable, and they don't let ANY water touch the floors. :) i just had to trim around the dead pedal a little bit. :)

jake, will do. :)
 
#12 · (Edited)
This thread is completely useless without pics...uh, never mind.

Seriously nice writeup!

Could a mod save these pics somehow on this server so we don't lose them when the photobucket links die.


Also, could you do this without removing the cooling unit (goes in place of the duct between heater box and blower fan)? It'd be nice to be able to do this without needing to purge the a/c system.
 
D
#13 ·
Final Step Omitted, but provided here:

These pictures and the comments indicating the sequence in which to take things apart were very helpful. The one omission was the final step of how to actually remove the heater core itself from the plastic case containing it.

1) remove the obvious screws attaching the case to the pickup. You do not need to remove the three hold-downs which secure the tubes to the plastic case.
2) The two copper tubes of the heater core are not detachable *inside* the cab. They go through the firewall to the engine compartment. You must open the hood and remove the two heater hoses from the copper tubes.
3) I was fooled for awhile by the fact one of the tubes appeared to be fused to the plastic above it. This confused me as I tried to understand how I was supposed to remove the heater core, then I realized the plastic had accidentally melted onto the tube because of inadequate spacing and/or insulation. I then severed that connection by scraping at it with a screwdriver.
4) Remove cables connected to the plastic case, and label them as to where they attach (or photograph them)
5) You should be able to pull the plastic case clear out once you pull the two tubes free of their holes through the firewall. Be careful not to turn it sideways or you'll spill out the anti-freeze onto your pickup carpet.
6) Take the unit to a bench and, with a little inspection, you'll see how to separate the plastic case into two halves and push/pull the heater core out of the case. Be sure to remove the three hold-downs that affix the tubes to the case. In case your heater core turns out not to be defective, be careful when extracting it *not* to put undo pressure on the two tubes where they attach to the heater core or you will crack the solder joint.
 
F
#14 · (Edited)
Thanks for posting this how to. I searched before I did my core and this was the best out there. I wanted to add pictures of the box and note that there is an O ring that should be replaced where the removeable brass tube goes into the core. I reused the half moon clip that holds that tube to the core but used a pinch clamp to secure that half moon clip in place. But the pinch clamps job was to apply pressure all the way around the half moon clip to keep it in place. That brass tube to core connection is a tight fit. I had to use some silicone paste to install the tube to core after using scotchbrite to scuff the tube and inside of the core to polish those areas to fit inside the new core.

One picture is of the white plastic multi piece door flap levers on the side. I forgot how it went back together and it took me longer than it should have in order to get it back correctly.

Another picture is of the finished modification. Some napa weatherstrip between the modified clamp and the core. Once I put that pinch clamp in place I couldn't use the factory hold down clamp as it was originally designed. Overkill on this but I wanted to give others the idea to use if they wanted.

I priced the core at the dealer, about 280.00, and a Macs radiator or other aftermarket core was about 100.00 dollars. I went for the less expensive one. The long brass tube had to be bent a bit in order to fit into its hold down on the heater core box. I worried about that soldered connection point to the cores upper tank but there was no problem. I do think that it takes about 5 minutes longer to get to full temperature, the air out of the ducts takes a bit longer to get as hot as it did before. This a/m core was a bit smaller than the original but I put some napa foam around the sides and bottom to stop air from going anywhere but through the fins of the core. I made sure the door flaps were adjusted correctly too while I was assembling it. I wonder if the aluminum factory core, and if I remember right, it was a bit thicker, was a more efficient core. Given the price difference I still would have gone the less expensive route though.

So here are my pics to add to this already awesome thread.





 
F
#15 ·
Bump for a helpful thread.

I just finished replacing the heater core in my pickup today. Everything went smooth except for the heater hoses under the hood. I had a b*tch of a time disconnecting them and then after I got everything back together, one of the hoses leaked. I ended having to buy a piece of hose and new clamps to keep it from leaking.

Other than that, this thread was an excellent reference. :thumbsup:
 
#16 ·
Bump.

I'm going through this process with a 1994 pickup (3vz-e, DLX) *with A/C*.

I'll try to post photos, as there are some important differences.

My question: Can anyone give me a handle on how to purge the A/C system without dumping my R134a into the atmosphere? I may be search-function-impared... But I couldn't find anything on this, other than long diatribes and debates over the relative merits and demerits of r12 vs r134.

Call me a hippy, but I'd rather not dump this crapola into the air for my great-great-grandkids to huff...

And to the OP: thanks for a killer writeup. It's been super helpful.
 
#18 ·
snollygoster86 said:
My question: Can anyone give me a handle on how to purge the A/C system without dumping my R134a into the atmosphere?
Click to expand...
You're supposed to have a licensed A/C tech evacuate it with refrigerant recovery equipment.

If your truck has the original R12 and you want to keep it R12, you just about have to recover it and reuse it at over $100/lb for new.

R12 = ozone holes.
134a = global warming.
 
F
#17 ·
I have ac on my 94 4 cylinder, engine difference "probably" doesn't matter? But I didn't have to evacuate the AC system on mine. You do have to do a little wiggling to get the heater core box away from the evaporator setup but it's really not that bad. It takes a lot less time to work around the slight difficulty in working with the charged ac system than it would doing the evap and charge program just so you can move the evaporator housing out of the way.
 
C
#19 ·
Excellent write up.
I'm struggling getting the main dash off. There are a couple of clips up near the windshield that some posts from the dashboard go in
I don't want to break the posts. Any suggestions how they come off?
 

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#21 ·
Great write up, thank you. Was able to get the old core out no problem (91 Toyota Pickup). Problem is it is copper, as well as the extension tube off the top. All new cores that I can find anywhere are aluminum and do not include the extension tube, at least the ones I've tried and from what I can see online. Does anyone know where I can get the bent aluminum extension tube (the one that takes the O-ring and clip) or a copper heater core?
 
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