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How to: 1st Gen Explorer Heater Core Replacement Diary

Discussion in 'Stock 1991 - 1994 Explorers' started by Glacier991, May 12, 2005.


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    1. Glacier991

      Glacier991 EF Tranny Guru Moderator Emeritus

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      [Preamble: Ok.. I know it is no big deal, not much harder than changing a spark plug, but ya know, we all started someplace in our auto repair, and this one is a good "starter" job for a newbie mechanic.

      So.... that said, here we go:

      Ah, summer, the time when a young man's heart turns to.... heater cores? Usually this time of year is when the AC threads start up, but a heater core failure is no respecter of seasons.

      If you have never had a heater core failure, they often show up in a way that scares the bejesus outta ya.... a puff of what looks like smoke appears at the vents! Whoa nellie, get out the fire extinguisher! Not. The leaks usually are so ssmall they atomize antifreeze and it shows up looking for all the world like smoke or steam. Relax, well sorta relax, you have a leaky heater core. Is all. No big deal for us 1st Gen Explorer owners, as you will see.

      Now the heater core is a pretty simple device, a little radiator really.... and in summer you COULD just disconnect the two hoses going to it, and using a hose connector and clamps just hook em together and wait til fall - I know, been there done that. But I decided to just go ahead and replace mine, and do a photo thread of the process.

      In the years I have been doing car stuff I have replaced a "few" heater cores (including this one! More on that later) and I gotta tell you... FORD hit it out of the park on the first generation Explorers in this department. It is a very easy job, 4 screws and 2 hose clamps - that's IT. No dropping the dashboard (81 Cougar, an ALL day job) or wierd contortions to get to it.

      Ok let's get at this task. The heater core is in a little chamber under the glovebox, and the hoses connect on the firewall just behind the glovebox, here:

      [​IMG]

      The "box" (if you like $5 words I think it might be properly called a plenum chamber) is in 2 "clamshell" halves.. it looks like this as it just sits there:

      [​IMG]

      and 4 screws hold the box together... I'll show you the first 3, the 4th is just in the back on the center hump side.. here is 1

      [​IMG]

      and two

      [​IMG]

      and 3

      [​IMG]

      These screws are 5/16's. the back most ones need something short, a 1/4 drive socket is perfect for them. There is one more I didn;t show, it is near the back. With all 4 removed it is easy to take off the front of the "box".

      [​IMG]

      Look at the AF in this one, think I had a leak?

      You will notice it has a drain so it won't leak into the passenger compartment should it fail.. nice touch!

      [​IMG]

      Once the front is removed, you are AT the core... (sounds like a bad sci fi movie, eh?) From the looks the leak was somewhere near centerline....

      [​IMG]

      Remove the hoses (sometimes easy sometimes you need to cut them off, don't worry, you have enough extra to do that) and you have just the ends of the core tubes sticking out..

      [​IMG]

      pull the core into the passenger compartment until the hose connectors clear the firewall, then down and out. EASY ! Disassembly COMPLETE !

      Looking at the core, it appears this one started leaking at the top seam...

      [​IMG]

      upside down

      [​IMG]

      since it was less than 4 years old good chance of electrolysis (more on this later). The new one is more or less identical.

      This is a place where a helper can be nice. I did it without one, but there is nothing holding the core in place but the hoses. Reinstallation is just reverse of taking it out.. carefully up then thru the firewall. A helper can apply pressure on the core while you work the hoses on. Tighten the clamps, put the box half back on and add the 4 screws, and YOU ARE DONE !

      Whoever figured this one out at FORD ought to get a bonus. Unfortunately later Explorers do not have it this easy.

      Now about the core. The core that went I picked up a few years at Autozone for under $20. The new one I bought at CarQuest for close to twice that. Side by side they look nearly identical. Was the Autozone one bad? Well maybe, maybe not. If a heater core fails in short order, suspect electrolysis. How to check ? Put a voltmeter probe in the antifreeze and one on the battery ground. Anything around .2 volts or higher is BAD news.
      I had replaced the radiator, flushed the system and added new AF since the heater core was installed, so of course it checked out ok - NOW. But, I could have had electrolysis before. So no verdict. The Carquest core was "made in the USA". We'll see.

      Anyway, now you can have heat in your Explorer this summer. In Minnesota it will be a blessing. Ok you guys in Florida can stop laughing now.
       
      Last edited: May 12, 2005
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    3. 85Dave

      85Dave Active Member

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      Awesome! When you replaced either of the heater cores, did you notice any debris buildup? Leaves, dust, dirt, hair, etc?
       
    4. Glacier991

      Glacier991 EF Tranny Guru Moderator Emeritus

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      No nothing of that sort. Not sure with the Explorer setup if they could get in there in any event.
       
    5. Tony H

      Tony H Well-Known Member

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      Easy, just like the old days. Too bad in many cars the are so buried. They go bad often enough that they should be as accessible as this.
      Nice pics considering where you are working.
       
    6. rocco123

      rocco123 Active Member

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      Thanks Glacier. Another well explained article.
       
    7. techieman33

      techieman33 Explorer Addict

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      Nice write up, i remember when mine went it scared the hell out of me, and I was even more scared when people kept telling me horror stories about replacing the heater core's in their cars, It was a big relief when I finished in 15minutes, I just with this thread had been around then.
       
    8. Brigrat

      Brigrat New Member

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      I hate to dig up an old thread, but I just inherited a 93 that is on its 4th heater core in 6 years. This Exploer is destined to be my beater trail/beach rig. I have two quetions:

      1. What could cause the heater core to keep going out?

      2. What would be the consequences of not having a heater core, and just connecting the two tubes together.

      Winter was mentioned, but I do not live in a cold area, and I would rarely drive this rig in the Winter anyways.
       
    9. Tony H

      Tony H Well-Known Member

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      The only thing I can imagine is Stressing the tubes during installation will cause them to fail.

      Just Bypass it if you don't need it. No negative affect on the engine.
       
    10. lifeguard379

      lifeguard379 Well-Known Member

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      another good trick is to put the caps from the new hc in the old one befor you pull it out so you dont spill af all over your carpet. ( i found that out the hard way)
       
    11. unclemeat

      unclemeat Well-Known Member

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      This is just what I needed to see. I need to replace mine and I had bad feelings about spending a whole Saturday doing it. I may go buy a new one today. Yea ha.
       
    12. Creager

      Creager Well-Known Member

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      I probably should do this also. How much do these heater-cores usually go for? $30?
       
    13. Glacier991

      Glacier991 EF Tranny Guru Moderator Emeritus

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      Yeah around that. Brigrat, 4 cores that fast certainly suggests electrolysis. But this is so cheap and so easy why not flushand replace your coolant and then the heater core and be done with it for now? This is truly a 30 min job. Why be without heat for that little effort?

      PS. Put a new 12 gauge wire from the engine to the battery Negative terminal while you are at it.
       
    14. Christobal65

      Christobal65 Active Member

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      Am I the only one that had issues getting my hoses to seal on to the new heater core?

      I did this about 3-4 months ago and had one hell of a time getting the hoses to seal properly. I replaced the clamps with better ones the the stock ones, cranked them down nice and tight but still had leakes...I am not sure what i did to get it to stop, but it did.
       
    15. arcblue

      arcblue New Member

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      Glacier991, thank you for the detailed description with pictures. I just did mine last night. I was going to tackle it myself this weekend but got the help of a mechanic friend. A couple of other issues with this job: The new core's input/output tubes needed to be "adjusted" a bit so they were the right distance apart to fit thru the holes in the firewall, and we had to come up with some weatherstripping to put around the new core (the old one used foam tape, which we couldn't reuse on the new core). Also, be prepared for coolant to come gushing out for a few seconds when you remove those hoses. We also replaced the old-style hose clamps with a newer design. So nice to have this fixed so I can turn on the blower again and smell nice clean air.
       
    16. biggs92EB

      biggs92EB Elite Explorer

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      just did my heater core yesterday, it was easy. i did have debri in the box though, my question is, is it completely necessary to have the weatherstripping around the new heater core? i put it back together without it, and im not sure if its gonna rattle around and break in there, i do ALOT of wheelin so...also i had to cut a piece of hose off so now i dont have enough hose for the one that goes to the water pump. i cannot for the life of me get to the clamp on the waterpump side, do i have to take out the fan? or is there a trick that i dont know..thanks james
       
    17. bikerchick4God

      bikerchick4God New Member

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      MANY THANKS for the instruction. was quoted $400 for a 4 hr job to replace this! dang!!!! I was gonna cap off the lines but have decided to replace the core as advance auto has it for $21.88 in daytona beach!
       
    18. bikerchick4God

      bikerchick4God New Member

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      Some basic information is overlooked for newbies like me. Hope this helps someone else not waste hours trying to figure this stuff out.
      I didn't know how to remove the plastic rivets that hold the carpet in place under the dash! Finally found out: Grab the head with a pair of pliars, I used locking pliars, and pull hard. They pop right out. Pkg of new ones can be had from auto parts stores for around $3.
      Before replacing the heater core I flushed the radiator and cleaned the overflow container with a toilet bowl brush! I didn't know how to remove the wiring connector for the washer fluid pump. Called Ford: Use a screw driver to push each small, side clamp away from the connector and you'll see how it moves away to release the connector from the container body.
      Thanks. Forgive my language if it is not correct.
       
    19. gblues

      gblues New Member

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      I just did my core; this is my first experience with any sort of automotive work since high school shop class, so I'm very much out of my element. Here's my story:

      Got a new core at Napa for about $25 + tax. Got the clamshell open without any issues. The hoses were another issue.

      I loosened the clamps on the hoses, and the right-hand hose came off without too much complaint. The left hand hose, however, was stuck. I ended up having to... improvise.

      By "improvise," I mean cutting the hose off. I did the initial cut with an old beat up saw but the saw was more suited for metal and I didn't have a good angle. Plus, it was a crap blade. :) I ended up finishing the job with a steak knife!

      After getting the hose off, I still couldn't get the old heater core out because the bit of hose on the core simply would not come off. So, improvising again, I cut the stuck hose with the steak knife lengthwise.

      At last, I got the old core pulled and the new core installed.

      My next problem was reconnecting the hoses. The right-hand hose was a cinch, since it came off the old core without a protest. But I had a new problem: my amputation left the left-hand hose too short to reconnect! With dismay, I follow the hose to the other end; replacing the entire hose was out of the question for my time and financial budget. My wife had the smart idea of using a hose splicer (which I'd need anyway to join the two hoses if my core replacement went completely TU). Back to Napa!

      I ran the problem past the counter guys at Napa, who suggested cutting off a few more inches of hose, then using the splicer to join the main hose and the new fragment to the core. One splicer and 2 hose clamps later ($4 and change) and I'm back to work.

      The rest is pretty smooth sailing from there. I start by cutting my segment of hose (again, w/ the steak knife) and clamping it onto the core; I attached the splicer and clamped it down, and after everything was secure I fired up the engine.. and to my delight, antifreeze did not go spraying everywhere! I added a little antifreeze to replace what leaked during the core replacement.

      I haven't had a chance to test to see if the heater actually blows hot now, but looking at the old core I can't imagine it was working. Still, can't beat just over $30 vs. the $200-300 quoted by the mechanic.

      Nathan
       
    20. 73Elsinore

      73Elsinore Member

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      Just to add to this...

      - If you haven't replaced your heater hoses recently, this is a good time to do it. That way you can just cut the old hoses off the heater core tube connections and you don't have to wrassle them suckers off.

      - When you have the old core out, make sure the drain hole from the heater plenum going to the outside is not plugged up. They somehow do plug up with road debris. Mine was. This is the drain hole shown in one of the photos. If it's plugged, and the core fails, you get coolant all over the inside of the passenger footwell.

      - I had a brand new Ford heater core fail right out of the box. Installed it, drove the truck a few miles, and had coolant all over the ground, coming out of the heater plenum drain hole. Nice.

      - None of the aftermarket heater cores I got would fit in the plenum correctly. I couldn't stuff enough rubber in there to make up for the air leaks and the crummy fit. The Ford core was a perfect fit.
       
    21. Draegonsan

      Draegonsan New Member

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      I just wanna say thanks a ton..I posted a thread asking for help on this and withing minutes was directed here to the article...great directions very short and simple... i thought I was going to have to remove the dash..hence my last 2 monthst of suffering in the cold here in nebraska. Now I know and this is getting done tonight. lol thanks a lot ill update ya'll on how I do.
       
    22. EurekaExplorer

      EurekaExplorer New Member

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      Thanks for this thread. Another piece of excellent assistance this forum provides for Explorer owners. This one is exceedingly grateful to the membership here for saving me from paying thousands of dollars to overpriced :D mechanics.

      ABakaEE
       
    23. yellowcat

      yellowcat Active Member

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      this makes me want to find an aerostar forum

      man the ford aerostar with there quick connects and there special heater lines. I totally outsmarter ford on that one. the heater cores at autozone were a very poor quility, I went to a radiator shop and paid twice the price for a very nice made in america core. Also that metal tape can work good for little leaks. My heater core on the aerostar was flopping around a little, but it never caused a problem. Glad to see something on the explorer is easy to fix
       
    24. MikeP

      MikeP Active Member

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      How does one remove the outer cover which is attached with two fasteners? Glacier991's 2nd photo shows the fastener hole (reddish color in photo). The two fasteners do not appear to be screws or bolts. I was thinking of merely cutting them off but there must be some reasonable method of removing these two fasteners (hold the outer cover to the metal on the dash). I am going to replace the heater core in my 1991 Ford Ex 4x4 with about 250,000 miles. My last heater core was installed in 2005 and that replaced the original heater core.
       
    25. markojay

      markojay New Member

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      hello...I noticed this threat is basically for 91-94 Explorers. I have 1995 Eddie Bauer, and am still searching for set-by-step heater core replacement instructions. I am told that I must remove the whole dash, but am looking for similarities with the earlier models. Will I need to remove the whole dashboard, and do u have the step-by-step instructions for that? If so, what is the url?

      thank you
       
    26. blueovalhawkfan

      blueovalhawkfan New Member

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      Is this just as easy in a 93 Ranger?
       

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