How to bypass heater core?

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Apr 14, 2012
Hello All - I have a fully stock '84 FJ60 and I'm pretty sure my heater core is leaking badly as I have a pool of coolant on the passenger side floor. I've ordered a replacement core from rockauto (we shall see if it's the correct one or not...), but this is my daily driver and I'd like to bypass the core until I can get around to pulling the dash and fixing it.

I've searched around and seen the question asked, but not directly answered - so, any recommendations of how best to bypass the heater core? I've got extra hose and fittings if I need to cut or reroute.

My original plan was to just disconnect the hoses that go to the core through the firewall and connect them to each other, but I'm having a hell of a time getting them off the old pipes that pass through the firewall and I really don't want to destroy any of the hard lines as they seem hard to come by these days. Is there an easier/better place to bypass? Any other tips for this job?
I haven't looked at the lines to the core on my 62, but I have a '66 Corvette (the interiors are notoriously hot in the summer) and we just put a simple shutoff valve in each of the 2 hoses running to the core so we can shut it off during the summer to prevent residual heat from coming into the cabin on these. I'm sure this would work on the FJ too, to prevent a core leak...
That could work - thanks. Is there any harm in stopping the circulation?
Not on the older cars...I can't imagine what it would hurt. Hopefully someone else with a better knowledge of this system will chime in tomorrow...
No, no harm in stopping the flow through the heater circuit. That is what the stock heater valve does.

To bypass the front heater in an emergency, cut the rubber hoses to the heater core and put a smooth shank 5/8UNC bolt in each 5/8 hose with a #10 hose clamp. For the hear heater, use 1/2UNC bolt.
Fantastic - Thank you, Jim.
So just to be sure I'm understanding correctly, in the photo below (not my rig) I'm going to detach and plug hoses #2 and 3. My rear heater isn't leaking, so no need to mess with the others?

Also, curiously I can't seem to find a decent diagram of the cooling system that includes the heater circuit in the 1980 2F Engine Manual I have. Does anyone know where I might find one? Thank you.
heater lines would would be in the body and chassis FSM I think, not the engine cooling/engine section

1980 FSM may be too old, you need 8/80+ I think

the early fj40's had 2 valves under the hood that you could shut off the flow to the heater, pretty nice to have, I shut mine off every summer in the 45
Plug end of hose #1 instead of #2.
Plug #3 too.
Fantastic, thanks! - My floorboard thanks you too.

And thanks all for the other suggestions as well. I still haven't found a good diagram of the heater circuit for a 2F in a 60, but I'll update this thread with a pic of the solution I end up with after diving in tonight.
Here's some drawings ('86)

heater core bypass.jpg

And here is the heater core bypass solution in action. I went with the method recommended above by Output Shaft and FJ40Jim and plugged the #1 and #3 hoses from the picture above using bolts in the hose ends. I already had a coolant flush T installed in #1, so that was easy. It is hard to see but #3 is plugged same as #1, I just had to use a new hose as the original is too short to stuff a bolt in. Benefits of this approach is that I can take my time replacing the heater core now that it is no longer leaking all over the place, and the rear heater and everything else will work just fine in the meantime.

Note also that RockAuto has two listings for a FJ60 heater Core. The Spectra 94658 was out of stock, so I ordered the other one:
APDI/PRO 9010348 {#8710790A00}. This is the wrong heater core - it will not fit. I'm sending back and trying the one available from JTOutfitters.
Just to wrap this up - Both the heater core from RockAuto and the one from JTOutfitters was not the correct one. In JTOutfitters defense, I think the one they sent me was for a '40 but was just in the wrong box - though I did have some issue getting my money back from them after I sent it back until PayPal stepped in. Anyhow, the one available on ebay from radsus (1981-1990 Toyota Landcruiser New Heater Core | eBay) is correct, was shipped quick, and only about $130 shipped.
Plug end of hose #1 instead of #2.
Plug #3 too.

Is it possible to simply remove hose 2 and 3 and use another hose to connect from the pipe connection of #3 to the valve connection of #2 ? This would simply be connecting the pipe to the valve and having nothing attached to the heater core.
2 could be connected directly to 3 with an appropriate piece of hose and couplings (if the water valve didn't leak). Keep the valve in the OFF position to keep the water flow through the head flowing normally.
Is it possible to simply remove hose 2 and 3 and use another hose to connect from the pipe connection of #3 to the valve connection of #2 ? This would simply be connecting the pipe to the valve and having nothing attached to the heater core.

Thanks for the reply but after thinking about it for awhile I don't think my idea of pipe connection of 4 to hose connection of 2 is a good idea. If the typical flow when the heater is connected is hot from engine at 1 through valve into heater core via 2 and then cooled liquid out from heater core at 3, then my idea would introduce uncooled liquid where there shouldn't be.

I think I will just do what you guys said at the beginning of this thread.

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