I've had a 77 with the external mounted rear heater and that one really cranked out the heat. I now have a 1981 FJ40 with the rear heater inside/under the center console and it doesn't blow for $h!t. I'm wondering if that's normal for these or if I should pull and take it apart to clean up and lubricate?
FJ40 Rear Heater Performance (1 Viewer)
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They get pretty warm and I can feel a little bit of warm air coming out of the bottom of the 2 rear vents but to say it's blowing out would be a lie lol.
I can roast marshmallows on my 74 heater 
The heater tubes going to it will melt residential pipe insulation.
I can’t imagine your newer one is working right.
When was your thermostat replaced in the engine?
The heater tubes going to it will melt residential pipe insulation.I can’t imagine your newer one is working right.
When was your thermostat replaced in the engine?
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Pull the fan out and lube it up. Lightly clean out the commutator grooves with s small flat blade screwdriver then lightly sand the commutator. Should go like the clappers. Im thinking of installing a rear heater that i have in the front of my 64 swb fst as it has no heater
if both of the hoses/pipes are hot and you are saying it is an air flow thing,
you'll need to remove the console and get to the fan, either it is not spinning fast enough or most likely the heater core is plugged on one side or the other from accumulated crap and needs to be cleaned
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1MOA
SILVER Star
Blow the fins out. I had a rear heater that would get hot but would not transfer heat. I washed it out and the fins were caked shut with mud. At some point in its life the truck got wheeled hard in some mud and it got into the cab and clogged the heater core up. It looked OK from the outside but was almost a solid brick when you got down and looked at the fins.
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Ok, yeah that's how my 77 was. From the "looks" it appears the thermostat has been changed, all the housing is clean and new, my front heater blows pretty hot.I can roast marshmallows on my 74 heater
I can’t imagine your newer one is working right.
When was your thermostat replaced in the engine?
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- #9
Ok , makes sense. Thank you !!!
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- #10
Alright wow !! This one spent it's first 30 years in Cali and then Seattle so who knows how much use it got but being in NE Ohio it's a requirement now Lol. I ran it today for about 40 minutes the front heater was blowing hot the pipes/hoses going to the rear were warm not super hot of course the insulation is very good on em though. I'll add rear heater removal to The List
Thanks again !
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My rear heater does not work in my '76 40 either. I'm not sure were to start first. I do know the thermostat is new. I'm assuming I should start with disassembling the rear heater itself first? Will I need to plug the lines going into it? Wondering how much fluid may come out of those lines upon removal of the unit itself
My rear heater does not work in my '76 40 either. I'm not sure were to start first. I do know the thermostat is new. I'm assuming I should start with disassembling the rear heater itself first? Will I need to plug the lines going into it? Wondering how much fluid may come out of those lines upon removal of the unit itself
@Rock Slide it will be about half a 5 gal bucket.. ive done it twice in the last year..
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if the front heater is nice and hot, it is not a thermostat issue.
@TL44 is there a valve and is it open? it has been a while since dealing with the 81+ rear heaters but I thought there is a lever sticking out the rear of the housing that operates a valve.
the rear pipes/hoses should be just as warm as the pipes/hoses going to the front heater.
post 12 in this thread shows the valve lever
forum.ih8mud.com
@TL44 is there a valve and is it open? it has been a while since dealing with the 81+ rear heaters but I thought there is a lever sticking out the rear of the housing that operates a valve.
the rear pipes/hoses should be just as warm as the pipes/hoses going to the front heater.
post 12 in this thread shows the valve lever
For Sale - FJ40 Center Console (late model)
Late model console $150 Haven’t seen one of these for sale in awhile and I’m not gonna use it like I planned.
forum.ih8mud.com
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Cromagnon
SILVER Star
It really helps if the description/symptoms is more concise i.e. "my rear heater is blowing cold air while my front heater is running like a blast furnace." Just saying "my heater doesn't work" is so wide open and involves so many sub-systems you end up with many more questions than answers. Is it a mechanical, electrical or cooling system problem? Give us more information and the answers will amaze you in the thoroughness in identifying and possibly solving the issue. As a start are the coolant lines hooked up to the rear heater? Does the blower move any air? Is the front heater putting out any warm/hot air? Are all of the electrical wires properly connected to the rear heater?
My apologies. It would help if I gave more info. Rear heater does not blow any air. Coolant lines are connected to the rear heater.
I'll check the front heater and report back. I've not tried it in so long, I can't recall if it blows air at all. I'll also check to see if electrical wires are connected to the rear heater.
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- #17
Ok and I agree (even though it takes a while for it to heat up & the temp gauge to come off the C mark)if the front heater is nice and hot, it is not a thermostat issue.
@TL44 is there a valve and is it open? it has been a while since dealing with the 81+ rear heaters but I thought there is a lever sticking out the rear of the housing that operates a valve.
the rear pipes/hoses should be just as warm as the pipes/hoses going to the front heater.
post 12 in this thread shows the valve lever
For Sale - FJ40 Center Console (late model)
Late model console $150 Haven’t seen one of these for sale in awhile and I’m not gonna use it like I planned.
Yes it does and it's open, if I put my hand on the floor by the rear vents I can barely feel warm air, so this appears to be more of a blower fan/air flow issue.
Funny thing is none of the pipes feel really hot, warm yes but not to the point that I can't keep my hand on them.
rkymtnflyfisher
Trout Bum
That tells me that the heater core is also clogged up, not allowing hot coolant to flow through the proper way. Both lines should be hot if it is working correctly.
You should flush both front and rear when you do it.
samatulich
SILVER Star
Just because your thermostat is new, does not mean it was installed correctly. I’d start by getting the truck hot and measuring the thermostat housing.
If your truck is getting up to temp, then I would look at the heat valve on the firewall. Make sure it is working properly.
While you have the valve off to inspect that it opens/closes, you can flush the heater cores out.
Disconnect both the inlet and return coolant lines at the fire wall. Use an air compressor/shop vac to blow air into the inlet hose and watch what comes out of the return line. I have done this on a vehicle before and was amazed at all the crud that was stuck in the heater core(s).
WARNING: this does not require high air pressure. I always start slowly and increase air pressure as needed.
If nothing else, remove heater cores and flush.
If your truck is getting up to temp, then I would look at the heat valve on the firewall. Make sure it is working properly.
While you have the valve off to inspect that it opens/closes, you can flush the heater cores out.
Disconnect both the inlet and return coolant lines at the fire wall. Use an air compressor/shop vac to blow air into the inlet hose and watch what comes out of the return line. I have done this on a vehicle before and was amazed at all the crud that was stuck in the heater core(s).
WARNING: this does not require high air pressure. I always start slowly and increase air pressure as needed.
If nothing else, remove heater cores and flush.
One thing I will never do is add tap water to the unmixed coolant, or use a garden hose to flush the system. Always distilled, even if it means looking like it is Y2K at the grocery store. Make sure that the top gasket is in place in the thermostat housing, or the thermostat won't be effective.
