FJ40 Rear Heater Efficiency

Joined
Nov 15, 2019
Messages
47
Location
Arlington, TX
How efficient are the rear heater unit in the FJ40s?

We are doing a restomod and don't know if it's worth reinstalling it if they do not heat worth a darn?

Is there something you can do to make them more efficient?
 
Joined
Nov 29, 2020
Messages
500
Location
Wausau WI
It's pretty simple, and it's a large heater core as it's the full circle...pumps out quite a bit of heat.

At least as much heat from the rear as the front, as it's a bigger core than what's in the center/front box. The fan is a bit funky, but you don't need to move that much air to get the heat transfer.
 
Joined
Nov 15, 2019
Messages
47
Location
Arlington, TX
It's pretty simple, and it's a large heater core as it's the full circle...pumps out quite a bit of heat.

At least as much heat from the rear as the front, as it's a bigger core than what's in the center/front box. The fan is a bit funky, but you don't need to move that much air to get the heat transfer.
Is all of the plumbing run inside the tub or does it go underneath the tub. The way we got it there was Plumbing inside the tub
 

John Smith

In the garage
Joined
Jun 7, 2004
Messages
4,289
Location
Maryland
Sure, super easy, invert so the inlet and outlet are vertical and fill with water, and see if it leaks. If you want to be extra sure, put a cap on both the inlet and outlet and poke a hole in one, and introduce low PSI shop air. You will know if you have any leaks.
 
Joined
Nov 29, 2020
Messages
500
Location
Wausau WI
Hose routing down the tunnel, for what it's worth...did mine just last week.

It all ends up under the factory floor mat, though.

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Hugh Heifer

Chasing the Beast
Joined
May 10, 2006
Messages
7,496
Location
Rome, GA
My front heater was gangbusters after I rebuilt it. (There is a thread.) I never had a rear until now. I will probably go ahead and plumb it for cold days in North Georgia. It doesn't take up much room.
 

1MOA

SILVER Star
Joined
Nov 7, 2017
Messages
1,696
Location
Warrenton VA
The rear heater rocks. The fan only kicks on at the “high” setting. And to be honest with just the heater valve opened and no fan the warm lines to the rear heater and radiant heat takes the chill off in the cabin pretty good.
 
Joined
Oct 10, 2020
Messages
90
Location
Near Omaha Ne
Just recently replaced mine with a used one from SOR. I think it was actually one for a later year as it has a 2 speed fan motor, instead of just a single speed. I just hooked up the wire to the high speed side. It puts out a considerable amount of heat. I'm thinking of adding another wire and hooking it into the front fan speed switch so that the low/high front fan speed also controls the rear fan speed. Originally the rear fan only came on when the front was selected for high.
 
Joined
Apr 21, 2005
Messages
20,601
The rear heater puts out a decent amount of heat. I don't need it hear in AZ but in Colorado the additional heat was welcome. If you have all the parts and the core is good, why not put it back in.

Where are you in AZ?
Believe you have an 82 which is different rear heater than the pre 8/80 rear heater. Not sure how much heat it puts out compared to the earlier round coil. Regardless moving it under the center console made it less venerable then sitting on the open floor. Sprung a leak in the rear heater coil in my 68 because of camping gear shifted and was resting on top of rear heater.

No need for it in TX, further north in Montana, heck yeah.

Not Texas but been Elk hunting in Northern Arizona when temperatures were below zero. Used the choke and hand throttle to keep the engine running in the morning while staying warm in the trailer. Both heaters running, transmission in gear and transfer in neutral so the gear oil in the transmission warmed up enough to be able to shift it.
 

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