The cheater's way of replacing a heater core

[timsrv]

I thought about naming this thread "The wrong way to replace a heater core" but for this old van there was no way I was going to do it the "right way". I'm not sure how long this job would take if were done the right way, but the method below will save a ton of time and effort (it took me about 2 hrs to do this).

IMO this is a stupid design. The heater core has 3/4" nipples that are over a foot long. These bend around different directions to eventually poke through the fire wall. To remove this core in one piece, the entire dash and HVAC "suite case" would need to be removed from the van. Well, that just wasn't going to happen so I devised a different way.
http://i8.photobucket.com/albums/a23/timsrv/01-5.jpg

These 3 screws need to come out, then the cover can be removed.
http://i8.photobucket.com/albums/a23/timsrv/02-4.jpg

Bracket and linkage need to be removed so we can slide the heater core out.
http://i8.photobucket.com/albums/a23/timsrv/03-4.jpg

Okay, here's a problem. The glove box is so deep the heater core will hit it when it's slid out. It's not meant to be removed with dash installed either (screws attach it from inaccessible angles).
http://i8.photobucket.com/albums/a23/timsrv/04-4.jpg

I have a plan though. 1st we need to protect the AC amplifier so it is removed by taking off these 2 bolts and letting it fall. I also remove the strut mount access cover.
http://i8.photobucket.com/albums/a23/timsrv/05-4.jpg

AC amplifier is unplugged and removed.
http://i8.photobucket.com/albums/a23/timsrv/06-3.jpg

The fun begins!
http://i8.photobucket.com/albums/a23/timsrv/07-3.jpg

I use a heat gun to soften the plastic glove box.
http://i8.photobucket.com/albums/a23/timsrv/08-3.jpg

The soft plastic is no match for my bottle jack! After it cools I remove the jack and the glove box retains it's new shape.
http://i8.photobucket.com/albums/a23/timsrv/09-3.jpg

Plastic and towels are laid down to protect the carpet.
http://i8.photobucket.com/albums/a23/timsrv/10-3.jpg

Brass nipples are cut using my air saw.
http://i8.photobucket.com/albums/a23/timsrv/11-3.jpg

Leaky heater core can now be slid out.
http://i8.photobucket.com/albums/a23/timsrv/12-2.jpg

Oh so close! Now the wheel well is preventing complete removal!
http://i8.photobucket.com/albums/a23/timsrv/13-2.jpg

Time for more trimming.
http://i8.photobucket.com/albums/a23/timsrv/14-2.jpg

Oh yeah! Sweet success!
http://i8.photobucket.com/albums/a23/timsrv/15-2.jpg

Plastic stand off is removed and nipples trimmed as required.
http://i8.photobucket.com/albums/a23/timsrv/16-2.jpg

http://i8.photobucket.com/albums/a23/timsrv/17-2.jpg

Using the file on my Leatherman I take the burs off the edges of the nipples.
http://i8.photobucket.com/albums/a23/timsrv/18-2.jpg

$10 salvage yard core is trimmed and deburred as required, then installed. I replace the missing sections of brass nipple with 3/4" heater hose. I am a little concerned about no barbs on the brass nipples, so I use 2 clamps on each connection. I also use some Dawn dish soap on each connection point for easy installation of the hose. When it dries, this will also act as an adhesive.
http://i8.photobucket.com/albums/a23/timsrv/19-2.jpg

Heat is again applied to the plastic glove box to make it soft and pliable.
http://i8.photobucket.com/albums/a23/timsrv/20-2.jpg

After reshaping, the only evidence is a white mark on the side. This will not be seen when glove box is crammed full of junk. AC amplifier and strut access cover are reinstalled.
http://i8.photobucket.com/albums/a23/timsrv/21-1.jpg

Linkage and cover are reinstalled (now cover only has 2 screws holding it on).
http://i8.photobucket.com/albums/a23/timsrv/23-1.jpg

[zepedrorusso]

You are an artist !

Great job !

[cvtroger]

I like that Tim.

What tipped you off the heater core was having issues?

[timsrv]

Drips on the carpet, the smell of antifreeze, and my defroster turned into a "froster". :wnk: Tim

[cvtroger]

Drips on the carpet, the smell of antifreeze, and my defroster turned into a "froster". :wnk: Tim

Oh, a major leak!

ps - going over everything I could possibly do while the motor is out and didnt even think about heater core.. might have to look into that too.

[JDM VANMAN]

I'm looking to pull a heater core from a 86' Van would it be approximately in the same location as the previa? I took most of the dash apart when I was pulling from it last time and someone came in after me and totally ripped the rest apart. So now it's more accessible but I don't know exactly where to look nor do I have a air saw to cut the pipes, or with it all open I just cut the connecting hoses and pull out?

Gonna pull the heater motor too now that I found your thread on that one.

Thank you:thmbup:

[timsrv]

If you lay down under the front of the van and look up, just behind the front bumper you will see a place where 2 heater hoses hook up to nipples coming out of the floor. These are the inlet and outlet nipples to the front heater core (core is inside the van buried under the dash).

[SamPrevia]

Amazing! Thank you for sharing.

ONLY 2 hours? That's even more amazing.

[photocopy]

Can confirm this is really easy. Took me about 45 minutes, i used blowtorch on glove box!

[93_Previa]

I am about to use this how-to in order to replace my 93 Previa's heater core (which is definitely leaking!). On your second picture of your how-to Tim, what used to be attached to the two black clips directly below the glove box (it's empty in your picture)? I know that you remove the A/C amplifier in a later step, but in the second picture, before you remove the A/C amplifier, what used to be there? I'm wondering because I have a 'black box' (not a flight data recorder, I can assure you) that is mounted on the underside of the glove box attached to the two black metal clips. I'm not sure what it does. Anyone have an idea?

Thank you Tim for providing this write-up!!! I will post back once I get a chance to do this (probably in a week or two, once the new heater core arrives).

[timsrv]

If you're talking about the 2 little plastic tabs hanging down, on this Previa, there was nothing there. Those tabs are used to mount the optional amplifier for Previas that have the premium sound system. The Previa featured in this write-up is a "plain Jane" w/the standard crummy stereo (no amplifier). Tim

[93_Previa]

Ok, great...I won't have any problem removing the optional stereo amplifier then. Just wanted to make sure it wasn't something critical like part of the airbag system or some other safety system.

One more question...in your third picture down you talk about removing the linkage (i.e. the tiny metal rod that attaches to the white clip below the heater core and allows an internal damper to be closed/opened). I was able to get the white clip on the bottom of the linkage undone. However, I don't know how to remove the top of the metal rod (linkage) from the connection up higher closer to the glove box. Any ideas? It looks like you were able to get this small metal rod (i.e. linkage) out before you cut the brass heater core tubing, but I can't figure out how to free the top of this linkage. Suggestions?

[timsrv]

Sorry, I did this in 2008 or 09 (it was originally posted on TVP) and it's been too long for me to remember. I don't recall that rod being a problem. If it were I'm sure I would have mentioned it. Let us know what you figure out. Tim

PS: perhaps you can push it and/or wire tie it up towards the firewall?

[zak99b5]

The Haynes manual says just to slide out the heater core after disconnecting the hoses leading to it (under the hood).

How is that possible with those long copper nipples??

[93_Previa]

I am about to use this method to replace my heater core and will let you all know how it goes. From my understanding, the Haynes manual is just plain wrong...there's no way you're going to just slide out the old heater core without doing Tim's glove box trick...there just isn't enough clearance!

[zak99b5]

Yes, after reading this thread I looked at the Haynes manual just for fun. They make NO MENTION of removing the nipples from the "firewall." It's got to be a joke.

[zak99b5]

Couldn't one braze or epoxy a short piece of copper with an ID that matches the OD of the nipples to create barbs?

[timsrv]

There's a lot of things one could do. This is just quick and dirty way. FYI, I've run lots of coolant lines on nipples without barbs before. The nipples are just extra insurance the line won't pop-off. Whenever I run a heater hose over a pipe with no nipple I always use an extra clamp. I haven't had one come off yet (knock on wood). Tim

[93_Previa]

I can confirm that this method works great as well...thanks Tim! This was a HUGE help and saved me upwards of $600-$800 if I had taken it to a dealer. No local mechanic was even willing to attempt it as the "official" way involves taking apart the dash and all the equipment :)

You can see some of my observations/tips on my original thread that I started when I wasn't sure what was causing the engine coolant leak out of the A/C drain tube at http://www.toyotavantech.com/forum/showthread.php?3825-Coolant-comes-out-of-A-C-condensation-drip-tube-any-ideas-what-s-wrong&p=22515#post22515

These TVT forums are awesome! Thanks!!

[timsrv]

Awesome! I think the dancing bananas are appropriate :dance2: :dance1: :dance2: :thmbup:

[Akagi82]

Wow... I love this.

[Jsp]

Thanks timsrv! Here's pics of the "playtrough"






First i heated up the glove box to make it nice and flexible and then i jacked it up.


http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_16_22_42_Pro.jpg
http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_16_22_56_Pro.jpg
http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_16_23_01_Pro.jpg


Then i used a steel saw blade to grind and grind and grind until i got the pipe cut.. The blade broke as you would expect.. Annoying but got the job done.


http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_17_38_01_Pro.jpg


And here's the culprit:


http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_17_37_47_Pro.jpg
http://i277.photobucket.com/albums/kk78/lollipop111_2008/1992%20Previa/WP_20161022_17_37_29_Pro.jpg


The top pipe broke off as i pulled it too hard..


And all this job took was one beer so i'd say one hour?
I looped the heater core piping so the car is now driveable.




Thanks timsrv for this tip!
NO MORE COOLANT FOG IN WINDOWS!

[timsrv]

Awesome! :dance2: Just be careful not to break the new one when it goes back in :yes:. Tim

[Jsp]

Going out for a drive now with the heater core tubes just looped with a rubber hose.. BRRR cold..
It's going to be AT LEAST wednesday before i get the "new" core from the junkyard.. Linked this thread to them as a tutorial how to remove it so i got it heaps cheaper.

[Jsp]

Okay just fyi to everyone. If your coolant reservoir starts foaming up. It's probably air bubbles escaping new core mixed in with some stopleak product.
I got a scare that it could be headgasket so i paniced.

[bytescream]

I am about to do this on my 1991. It sat for 6 years waiting for me to build my shop, drop the engine and repair the warped head that happened from running out of coolant. I have been driving it for almost a year now and STILL adding coolant. You can imagine my irritation with the idea that the new head may be warped.
But just this evening i spotted a puddle coming from the AC drain. The AC has not been recharged after converting it to the new refrigerant.
So happy to hear this news. I'll definitely do a heat warp and cut tubes.





Okay just fyi to everyone. If your coolant reservoir starts foaming up. It's probably air bubbles escaping new core mixed in with some stopleak product.
I got a scare that it could be headgasket so i paniced.

[stillgoing]

Sorry know this is an old post but had trouble today when the lever for going from cold to heat wasn't changing to heat. Io when i got home took a look at it and it seems to be the heater control valve cable is not moving right. i did take the cover off and saw the H/C and was amazed at how stupid a design it was. With that being said Tim why didn't you just take the tubing out of the firewall and run the new hose into the engine compartment by the H/C valve? On my 91 the tubes go through the firewall just a short bit then each one has a short piece of hose that then connects to more tubing. But great write up to save a lot of time and money. When owning these old vehicles never want to put any more money in then needed.