Trying to identify what these underbody pipes/conduits carry – Help!?

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ZackR said:
No doubt the front heaters are impressive..... however the rear heat is great for keeping the kids in the back warm without having to get roasted out up front.

Random side note - I'm surprised someone hasn't ducted the rear heater air output externally and connected the fan to a thermostat so that it can be used as an additional radiator in high engine load/temp situations.
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Agree. Sometimes I actually use it instead of the front, given it seems to spread heat throughout the cab a bit better/more evenly.
 
ZackR said:
No doubt the front heaters are impressive..... however the rear heat is great for keeping the kids in the back warm without having to get roasted out up front.

Random side note - I'm surprised someone hasn't ducted the rear heater air output externally and connected the fan to a thermostat so that it can be used as an additional radiator in high engine load/temp situations.
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If the kids want heat they can do what I did and get a job and buy their own heated chariots. The bums lost! :p

Yeah, I have been meaning to revisit the rear heat lines in my truck this coming summer. Your idea is intriguing though and I would subscribe to your newsletter if you had one regarding the topic. :)
 
jonheld said:
Exactly the same on all US spec 80s.
Not sure if the part numbers match, but if you have a heater under the front passenger seat, the lines are there.
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Thank you, @jonheld. I'll get to that when I'm under there during the replacement.

RE part numbers:
1991 Toyota Land Cruiser 4.0L AT Hose sub-assembly, water, c - 8720960120 - Genuine Toyota Part
1991 Toyota Land Cruiser Heating & Air Conditioning - Water Piping

and potentially 1992 FJ80 3FE Heater Hose OEM Part Codes
 
Last edited:
And lo and behold, PO already took care of the bypass. I went to start the repair and I was like, wait a minute, this looks like the end of the video, not the beginning. Thanks, everyone, for the tips.

bypass 1.webp


IMG_8261.webp
 
The two hoses attached to the heater control valve in your first picture look to be original and should be replaced. Also check the condition of the PHH and replace that as well if is still original. Search "PHH" will provide lots of pictures and information.
 
Red Merle said:
Good deal!

FYI, your wiring harness where it passes the EGR pipe looks a little crispy. I would address that. Did the PO delete the EGR system too?
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I’m actually still throwing CEL 401 code after replacing the evaporator diaphragm. Could that wiring harness be a possible cuplirit?

thanks!
 
snorig said:
I’m actually still throwing CEL 401 code after replacing the evaporator diaphragm. Could that wiring harness be a possible cuplirit?

thanks!
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They probably didn't install the bypass diode in the plug that fools the computer into thinking everything is okay.
 
RFB said:
dude bypass those today, they will not last up here in northeast and youll be bumming. hit up landcruiserphil or witsend tonight
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And don't bypass them down at the rear heater core, bypass them at the firewall!
 
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