'94 heater core R/R - done (2 Viewers)

[CaptainNemo]

Well it's back together and on the road again. Took me two weekends and a few hours here and there. I'm slow and distracted easily so that doesn't help.

This 80 has a little over 200K miles. Had the classic interior fogging and slight anti-freeze smell. We had a A/C leak before this so I had taken it halfway apart before.

Took a ton of pictures to help put things back together correctly. The pictures helped mostly on the routing of wire looms and such. The plugs only seem to fit the correct switch.

The FSM does a good job of leading you through most of it. Dropping the steering column helps a ton.

I'll post some pictures now...

Careful not to break these little tabs on this main upper trim piece>

locker, dimmer, mirror and OEM security>

Speedo and stuff>

I've had a 'D' bulb on the shelf for about 5 years. Forgot to put it in while it was all apart! Doh!

Hidden bolt under the false vent (US passenger side)>

n00dly appendages>

Gooey center>

Cross support bar was kind of a PITA to get out>

New core and CB. Also replaced heater hoses while I was there.

There is your problem>

The unit>

Inside the unit>

This is as far as you'll have to tear it down. All downhill from here>

I went with the constant torque clamps. Got them home and had buyers remorse. They are over $4.20 each. I used one for the PHH (block side) then bypassed the metal hose and used Breeze Liner Clamps for the rest. Took the CT clamps back to Napa and bought the liner clamps from a trucking company for a little over $1.30 each >

Breeze Liner Clamps

New core, new home. I think I paid like $260ish for the core>

Installed a new CB and MP3 Modulator while I was in there. I somehow lost the stereo antenna inside the dash monster and there was NO WAY that I was pulling sh1t back apart. The OEM antenna had been broken twice so I replaced it and ran a new antenna wire trough the firewall. Need to have that stinking antenna to make a MP3 modulator work. Doh!

Cheap universal stereo antenna >

Mounted all the MP3 stuff under the shifter console and ran the wire out here>

All done>

Need to charge and check the A/C still. Overall it is not too bad. I was overwhelmed with the amount of stuff I kept pulling but, it went back together well. I think I spent the most time cleaning up a mess the alarm installer created several years ago. Hope this helps someone.

Later,
Brian

Any chance your photos are still available? I'm face with a potential heater core replacement. No worries if not.

 

[mrq]

Any chance your photos are still available? I'm face with a potential heater core replacement. No worries if not.

I had my heater core replaced last month. It was leaking anti freeze onto the passenger's floor mat under the dash. The shop I went to said that OEM new FZJ80 heater cores aren't availableand that the only option was to rebuild and re-core my heater core. So that's what they did. It cost about $2200 for the heater core replacement & re-build.

You have to remove the whole dash in order to get to the heater core. So it's a pretty big job.
Here's a photo of what my rig looked like while they were fixing it.

You definitely have to know what you're doing in order to replace the heater core. I am not a mechanic and have little skill with things mechanical/repair — so I had no choice but to have my LC mechanics do the job.

Good luck!

 

[flintknapper]

^^^^ Oh man....hope I never have to do that!

 

[CaptainNemo]

My resolve is being tested. I think I'm in the eye of the perfect storm. My heater core is leaking, I just tripped a fault code for P0420, I have a seized spark plug, and my transmission is failing, I think. I've been losing drive-force the last few weeks and can barely make it up small hills (Engine and transmission windy, whining, and downshifting so quickly with no power.) My resolve is being tested. This 1996 LX450, at 297K miles is seeing it's last days, and will, most likely, need to move her to geriatric care and put her on morphine.

 

[CaptainNemo]

My faith has been restored. I recant everything I said in my moment of weakness. My local transmission guru just test drove my LX450 and explained that the transmission is in perfect condition. He told me that the power loss is due to a phenomenon related to the check engine code P0420. The P0420 code was triggered after I replaced both oxygen sensors to clear yet a previous code. The previous code was a bad oxygen sensor #2. The transmission shop told me to replace both sensors again and also check for a clogged Catalytic convertor. Wow. I'm now going to see if I can get my money back on the 02 sensors.

 

[CaptainNemo]

My two Denso oxygen sensors (purchased from Rockauto.com) checked out fine. Hot off the press from professional diagnosis

"Hooked vacuum gauge to intake manifold and found vehicle would build 1 psi under heavy load indicating a restriction in the exhaust. Recommend replace catalytic converters and retest."

The restriction is creating a back pressure in my exhaust causing massive loss of power. Also, seems you need to keep the original box to comply with warranty policy, hence I could not of returned anyway. Seems I need to replace two catalytic converters, CARB approved. Looking at $433 not including install. From "buyautoparts.com."

 

[John Young]

I'm in the middle of this too on my 1993. Leaking heater core. I found the extract of the FSM that reveals the location of the screws and the sequence but I'm kind of stuck. Something is holding the upper center of the big dash pad in place. Both ends are freed. This is where I am at the moment:

My next step will be to take out the center console, but that does not seem to be where the hold up is. I've searched and searched for a step by step with photos to no avail. Any suggestions would be gratefully received.

 

[JSG]

My two Denso oxygen sensors (purchased from Rockauto.com) checked out fine. Hot off the press from professional diagnosis

"Hooked vacuum gauge to intake manifold and found vehicle would build 1 psi under heavy load indicating a restriction in the exhaust. Recommend replace catalytic converters and retest."

The restriction is creating a back pressure in my exhaust causing massive loss of power. Also, seems you need to keep the original box to comply with warranty policy, hence I could not of returned anyway. Seems I need to replace two catalytic converters, CARB approved. Looking at $433 not including install. From "buyautoparts.com."

View attachment 2110607

I’ve been having the same issue recently with barely making it up small hills. Mine isn’t downshifting, I was thinking a sensor, perhaps. Did replacing the cats solve the problem for you?
Also, OP, thanks for the writeup & pictures! I’m losing coolant, passenger carpet is damp, this is likely something I’ll need to tackle once it warms up here and this is going to be a great help.

 

[Pericles]

Any chance your photos are still available? I'm face with a potential heater core replacement. No worries if not.

Ditto on the pics. I'll need to tackle this at some point. Trying to buy some time with Bar's.

 

[CaptainNemo]

 

[CaptainNemo]

CAT suffered a catastrophic melt-down causing enormous loss of power. See first photo. The second photo is what it should look like.

 

[Pericles]

Ok. So, I just completed this job. I've seen folks commenting with questions, so I'll add my 2 cents.

First, it looks far worse than it is. This job does not require any real mechanical skills, but simply the ability to follow instructions and either recall from memory where things go or the discipline to write them down or take pics. I didn't take any pics (disappointing, I know). I just followed the FSM to get the dash removed, and then improvised from there.

The FSM does a very good job of walking you through removing the large pieces of plastic that we call the dash. It'll basically get you to the point where all the trinkets, wires (Lord, the wires!), and what-have-yous are visible. I will warn you to be cautious when removing the steering wheel if you have never done that before/don't have a steering wheel puller. Nobody likes going to the dentist. So, keep that nut on a few threads deep.

After you get the dash removed, it's really just a matter of hunting for nuts and screws so that you can 1) remove the white box in the middle of your dash that houses the heater core and 2) remove the evaporator to the right of that white box. There are 8 or so nuts or screws holding these two boxes to each other and to the body. Go ahead and take care of those.

Now, the evaporator box and heater core box "hang" on the same bolt (once you're in there, you'll see what I mean) and the evap box is in front of, or must be taken off the bolt before, the heater core box. s***. For me, I simply could not get the a/c lines to give enough to get the evap box off the bolt and move over to get the heater core box off the bolt. Thus, I had to evacuate the a/c, disconnect the two a/c lines that are bolted to the evaporator at the firewall (two 10mm bolts), and remove the evaporator core along with the heater core box.

A few frustrated tugs and shakes and she's out of there! (Well, if you thought to remove the hose clamps on the engine side of the firewall.) Now, you can gander at your sad, rusty heater core.

Here, we're lucky enough to have a good radiator shop, and I was able to have my core repaired for $140. I had an aftermarket core from rockauto, but I simply felt better about having the original repaired by a good shop and putting it back to work.

CAUTION: the original heater core in my '93 (not sure about other years) has one pipe longer than the other, and this longer pipe has a joint in the middle. Said joint contains a rubber o-ring as a seal. Given that this pipe does not move or flex, I cannot fathom why this is not one single, bent pipe. Anyway, I'd suggest cutting out that section and replacing it with a good quality hose (e.g., Gates green stripe) and clamps.

Once you have your core, it's just "installation is the reverse of removal".

Hope this helps someone.

 

[John Young]

CAUTION: the original heater core in my '93 (not sure about other years) has one pipe longer than the other, and this longer pipe has a joint in the middle. Said joint contains a rubber o-ring as a seal. Given that this pipe does not move or flex, I cannot fathom why this is not one single, bent pipe. Anyway, I'd suggest cutting out that section and replacing it with a good quality hose (e.g., Gates green stripe) and clamps.

Thanks for posting this. I confess I also had concerns about that o-ring seal. I replaced the o-ring but still did not feel like it was secure enough. I wrapped mine with quite a lot of self-vulcanizing rubber tape which I have had pretty good luck with in the past. But your solution is interesting. I think on balance it might be better to have brass pipes coming out of the firewall, but that's just my personal viewpoint. The OEM brass tubes are no fun. Mine were pretty messed up so I had my radiator shop replace the tips and also extend the tubes by 1.5 inches to make attaching hoses to them easier.

 

[Pericles]

Thanks for posting this. I confess I also had concerns about that o-ring seal. I replaced the o-ring but still did not feel like it was secure enough. I wrapped mine with quite a lot of self-vulcanizing rubber tape which I have had pretty good luck with in the past. But your solution is interesting. I think on balance it might be better to have brass pipes coming out of the firewall, but that's just my personal viewpoint. The OEM brass tubes are no fun. Mine were pretty messed up so I had my radiator shop replace the tips and also extend the tubes by 1.5 inches to make attaching hoses to them easier.

Yeah, after taking out the entire dash I just didn't feel completely confident in that o-ring (although, if replaced, it's probably fine since the design has already lasted all this time). Design still puzzles me, though. Maybe it had to do with the way the pipes were machined/formed? To be clear, I only put hose where that joint was, so just about 2 or 3 inches total. The rest stayed stock. I've seen folks on here replace their entire cooling system with various types of hoses; no idea how that holds up.

I wish I had thought to get the shop to extend those tubes! Solid idea. Honestly, the hardest part of the job was re-attaching the hose to the tube that comes out behind the head/plenum.

 

[BILT4ME]

Here, we're lucky enough to have a good radiator shop, and I was able to have my core repaired for $140. I had an aftermarket core from rockauto, but I simply felt better about having the original repaired by a good shop and putting it back to work.

Please post the source of your core rebuild.

This shop may get more business than they expected.

 

[Pericles]

Please post the source of your core rebuild.

This shop may get more business than they expected.

Good thinking. I used Chatt-town: Chatt-Town Radiator Services - https://chatt-town-radiator-services.business.site/

This is my first time using them (thankfully I don't go through many heater cores), but they came highly recommended. Also, I should mention that they finished the job in one day, which I though was pretty exceptional.

The true test, of course, will come several thousand miles from now.

 

[John Young]

I used a great commercial radiator shop in Maryland. Photos of the shop and contact details here on this thread. Can't say enough good about them. Price was fine too.

 

[Guyute]

Wow. This thread brought back some foggy but sweet smellin memories. Like Pericles says above it seemed to look worse than it really was at every step. Peoples asking to repost the pictures missing in OP... I think I did repost everything I had years ago. Like page 2 or 3.

B