60 Front Heater Core Clean-up (1 Viewer)

[gregnash]

Ok so figured there were a few threads out there about replacing the heater core and the amount of disassembly it takes to get to the bastard thing. However, there is nothing about steps going to there or thought process (what to do first) when one is experiencing issues.

Some of you may know that I have been fighting with an intermittent working FRONT heater for years. Seems like the last two years have been the worst (since I rebuilt the head) where it just seemingly takes FOREVER for the thing to produce hot air. In the morning, at best, I get luke warm air when the engine is up to operating temp. With the colder months coming I would like to remedy this soon and will have some time during this month with the holidays and whatnot.

Symptoms:
Intermittent heat. Can go out in the morning, start up the truck and bring her to temp in 10-15 minutes of idling only to get luke warm air from the front heater. Rear is much warmer, not overly hot. This is in comparison to the first couple years of ownership when I would have blistering hot air.

- T-stat and proper gaskets have been replaced a couple times. Never had any issues with that where the upper gasket ring is the culprit and is not mounted properly. Have the high heat (I think) t-stat that doesn't open until 195*.
- Radiator is new as of about a year ago when mine developed a crack at the seam in the top tank. Replaced with a CSF brass core.
- Head was completely rebuild in 2016 due to a blown head gasket. No issues were found with anything at that point once rebuilt.
- Water pump was replaced with new unit at time of head rebuild
- All relevant hoses and what not have been replaced
- System has a mixture of 50/50 water and full strength green stuff
- Cleaned out the intake area of leaves in the front cowl as well as the fan assembly

One thing I do have is the burbling that would indicate there is some air in the system. This has always been the case and normally happens when the engine first starts up but goes away. I have checked the hoses that go to the valve on the firewall to ensure they are different temps and they hottest they get is 190*ish and lowest is 160*ish. So they are coming up to temp and does not seem like the valve is stuck.

This all points me to the heater core itself being the culprit. Either it is clogged internally with corrosion and rust or externally (fins) with dog hair, leaves, etc. I was lucky enough to pick up an entire heater core assembly on eBay a few months back for $90 that supposedly is a good unit and looking at it there is nothing indicating that it leaked or had issues. However, I am contemplating sending it to my rad shop and having them braze the firewall tubes together and do a full check to ensure.

But before I do all that and disassemble the dash to get to the bastard, I wanted to know if there is any flaw in my logic or if I was missing something obvious???

 

[georgebj60]

Did you flush out the heater core? It's fairly easy to connect some hoses up to a faucet or hose, just be careful not to blast at too much pressure. I would go with the flow for the first flush, and then reverse for a second flush. You never know, maybe there's something blocking it.

Also, I've found that most crud from the outside world gets caught in the AC evaporator, not the heater core. That box is fairly easy to remove and clean out, though you'll need to disconnect the AC to do it. You can also drop the fan motor and clean that out too.


Taking the heater core out is a time consuming job, but not a difficult one. But I would say if your current one is not leaking, I would remove it only as a last resort.

 

[gregnash]

Did you flush out the heater core? It's fairly easy to connect some hoses up to a faucet or hose, just be careful not to blast at too much pressure. I would go with the flow for the first flush, and then reverse for a second flush. You never know, maybe there's something blocking it.

Also, I've found that most crud from the outside world gets caught in the AC evaporator, not the heater core. That box is fairly easy to remove and clean out, though you'll need to disconnect the AC to do it. You can also drop the fan motor and clean that out too.


Taking the heater core out is a time consuming job, but not a difficult one. But I would say if your current one is not leaking, I would remove it only as a last resort.

Right... the flush is on the agenda to do. Not going to use muriatic acid or anything like that at this point. My system does not leak, at least from what I can tell/find, so the flush should hopefully do it. I have taken the fan assembly out and cleaned it, but if I remember correctly there really wasn't much in there to constitute a block.

Here are some related threads (many have missing/broken photos though)
5 hour heater core swap
Heater Core / 86 60 Front

 

[SteveH]

For diagnostic purposes, you might run the heater fan on high with the slider set to 'heat' and see if the inlet and outlet hoses show much temperature difference. This indicates whether the core is rejecting any heat to the vehicle. Never mind the actual temperature, what you want to see is the difference. If they are about the same, then your heater is either coated with a lot of scale, or clogged outright.

I have done a muriatic acid flush of just the core (removed from an FJ40) and it came out sparking clean inside and the heater was hot after that.

 

[Randy88FJ62]

Had no heat when I bought the truck.

-pulled out and acid flushed heater core
-replaced t-stat
-replaced all coolant hoses and inspected lines
-checked air box ducting

And what was it? The previous owner had mixed two of the hoses up and there was no coolant getting to the heater core. Amazing all the small details that can keep us from heaters working well.

 

[georgebj60]

I wonder if, after the flush you could bypass the heater valve to make sure that's not restricting any flow.

I recently gutted my entire dash, and rebuilt all the A/C, heater and fan boxes. It was a lot of work, but since I was in there anyway transferring my HJ60 24V harness into the FJ60 it was a no-brainer. If you need any pictures, let me know - I probably have it.

One word of caution, the heater core is NLA, and even cores for re-coring are hard to come by (at least according to my local shop that did the work). I was quoted $600 CAD to rebuild the unit.

In the end, I gave him both the cores from my HJ and FJ, and used the best of both parts and did it custom. I'm not sure just any shop would want to take that on though.

 

[gregnash]

For diagnostic purposes, you might run the heater fan on high with the slider set to 'heat' and see if the inlet and outlet hoses show much temperature difference. This indicates whether the core is rejecting any heat to the vehicle. Never mind the actual temperature, what you want to see is the difference. If they are about the same, then your heater is either coated with a lot of scale, or clogged outright.

I have done a muriatic acid flush of just the core (removed from an FJ40) and it came out sparking clean inside and the heater was hot after that.

So you are saying that I should try it on the heat setting and if I do not see a significant difference when measuring the temps of the hoses then the core is potentially clogged? Do you suggest measuring the hoses at the valve or the hoses coming directly out of the core? I will take the long way home tonight and give it a shot.

I wonder if, after the flush you could bypass the heater valve to make sure that's not restricting any flow.

I recently gutted my entire dash, and rebuilt all the A/C, heater and fan boxes. It was a lot of work, but since I was in there anyway transferring my HJ60 24V harness into the FJ60 it was a no-brainer. If you need any pictures, let me know - I probably have it.

One word of caution, the heater core is NLA, and even cores for re-coring are hard to come by (at least according to my local shop that did the work). I was quoted $600 CAD to rebuild the unit.

In the end, I gave him both the cores from my HJ and FJ, and used the best of both parts and did it custom. I'm not sure just any shop would want to take that on though.

This is exactly why I jumped on that replacement unit. Figure at less than $100 for the entire box, not just the core itself, even if mine turned out fine at the moment, I could potentially use in the future. One of those ones you really don't pass up and just squirrel away the part.

 

[Randy88FJ62]

@gregnash
Once you're home after the drive pop the hood and put your hand on the hoses going into and out of the heater valve on the firewall. If one hose is hot and the other cool then you can trouble shoot the heater core or the heater valve.

With the engine running it is easy to unhook the heater valve from the wire control and manually move it up and down while still being close to feel the hoses.

Pull heater valve and inspect, then if that is good you have identified your problem as a clogged heater core.

 

[gregnash]

So checked everything after running around town
Top hose into valve 155-160*
Lower hose into valve 135-140*
Lower hose out of heater core 135ish

Temp coming out of the vent in HEAT mode was about 130*
Temp coming out of the vents in DEFROST mode was about 130*

So thinking that the heater is clogged/blocked up?

 

[georgebj60]

I know when I had my truck inspected for safety, the defrost barely worked. I flushed the core, and bypassed heater valve.

I didn't get much junk out of the heater core, and the water flowed just fine. And after all that the defrost still barely worked.

I never looked into it further as I pulled the 2F to make room for the 2H.

All this to say the heater core may be fine, and the problem lies elsewhere.

I would say flush it and see what comes out. But don't pull it out unless you have to. Oh, and be careful handling those copper tubes out of the firewall. DELICATE!

 

[NookShneer]

@gregnash

I went thru the same thing. Mediocre heat at best of of the front and hot out of the rear heater. I tried flushing in reverse with water , then water and then adding compressed air (that was fun), then went with an muriatic soak overnight.

After all that same results across the board.

Bought a SOR replacement years ago and took the whole box to a rad shop to get the tubes soldered together. I figured if I was going to go thru all the effort I might as well “do it right, or do it twice”. While pressure testing the solder job the rad shop told me that they found two leaks in the new core they fixed them and the solder job for $43.

After all that. The front heat is warmer but still not as much as the back.

 

[georgebj60]

This is very strange. What could it be? Some people report blistering heat out of the main (front) heater, and others get lukewarm at best. My truck fell into the lukewarm (or non-existent) category. I hope it changes with the diesel engine.

But for the FJ's, what else could cause this? Restricted heater lines elsewhere causing low flow? Bad heater valve (though in my case it made no difference). Air pockets? I wonder if you could "pressure bleed" the heater core, and then re-connect the lines. Just thinking out loud....

 

[Feistl]

Couple of things... chances are the foam padding used to seal around the core has deteriorated... so air takes the path of least resistance (eg around the core rather than through it).

Or... even though the input/output temp of the core is high and the core flows well enough you might not actually have coolant flowing through. Could be because a previous owner has got the hoses confused and it isn't plumbed up right or there is a blockage somewhere downstream.

Ideally you want to disconnect the return hose and feed it back into the radiator fill point so you can physically see how much coolant is flowing (you'll need to block the end you disconnected from).

Otherwise pull the heater box and during rebuild make sure the foam is replaced in such a way to ensure correct airflow.

As for the cores being unreplaceable.... I'm about to rebuild mine (in a few weeks) so I'll find a core which can be swapped in from another vehicle with minimal effort/modification.

Cheers

 

[Randy88FJ62]

The pipes that run the coolant into and out of the heaters get corroded. The ends on mine aren't looking good. It's possible those could be clogged and letting very little flow through as well. I pointed red arrows at them in the picture below.

 

[SteveH]

Top hose into valve 155-160*
Lower hose into valve 135-140*
Lower hose out of heater core 135ish

Does your engine head measure (with an IR temp gun) about 200-205F when the engine is fully hot (like on a hot summer day)? To me, the 20 degree difference shows that your heater core is rejecting heat to the cab (as it should). I would also check for air leaks around the core, as Feistl suggested.

I'd like to see hotter water getting to the core inlet, however. Can you find a way to put your finger on the heater core (truck running and heater on) and see if it's quite hot to the touch?

At some point, you might remove and inspect the heater water valve, and be sure it hasn't fallen apart internally, and perhaps is not letting much water flow through it. If it's 30 years old, anything might have happened inside that valve.

 

[gregnash]

Good thoughts everyone. Plan is to do the heater core flush in the next couple weeks here (maybe this weekend if I can get the time between family events).

I was able to find a NOS OEM valve on ebay which will be coming from Japan just in case my valve is causing issues at the firewall.

And as far as I know I have always connected the hoses properly. This all started a number of years ago when I first got the truck and had the radiator run low and boil some of the coolant (maybe 6 months after purchase). Everything was fine for the remainder of that winter but after that was when things started getting lukewarm. I initially thought it was an issue with my t-stat and the top gasket not seating properly (which will allow the coolant to basically bypass the t-stat and not get warm), but that didn't turn out that way.

When I rebuilt the head and replaced the waterpump I figured it was a good idea to do again at that point so took care of it. But again, I have not had HOT air coming out of the system since maybe 2015. I will occasionally get hot air if I have been doing lots of errands and been running around a lot.

Top hose into valve 155-160*
Lower hose into valve 135-140*
Lower hose out of heater core 135ish

Does your engine head measure (with an IR temp gun) about 200-205F when the engine is fully hot (like on a hot summer day)? To me, the 20 degree difference shows that your heater core is rejecting heat to the cab (as it should). I would also check for air leaks around the core, as Feistl suggested.

I'd like to see hotter water getting to the core inlet, however. Can you find a way to put your finger on the heater core (truck running and heater on) and see if it's quite hot to the touch?

At some point, you might remove and inspect the heater water valve, and be sure it hasn't fallen apart internally, and perhaps is not letting much water flow through it. If it's 30 years old, anything might have happened inside that valve.

Yes, head is reading right around the 200* mark. I have not installed my Inclinometer yest so I think I can see the heater core top through that hole in the A/C cluster. I will see about getting a measurement from there after running some errands and having the heat going.

 

[Randy88FJ62]

Link to valve and cost?

 

[gregnash]

Link to valve and cost?

GENUINE TOYOTA LAND CRUISER FJ60 FJ61 FJ62 HEATER WATER CONTROL VALVE HVAC OEM | eBay
Act fast as they only have a few left. Looks like I may have gotten the last one!

 

[Randy88FJ62]

Good price for new OEM.

 

[gregnash]

Good price for new OEM.

Right!! Considering you can get from somewhere like ToyotaPartsDeal for around $60+ I figured I would jump on it when things started getting cold. Had been watching it for a while and decided to just do it yesterday, figured if nothing else it will be another part that goes into the squirrel bin.