Heater Delete Properly

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MatthewMcD

MatthewMcD

SILVER Star
Joined
Aug 10, 2023
Threads
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1,211
Location
Austin, TX
Website
gunsdogsandfood.com
I have set aside this wonderful 4 day weekend to finish the overhaul of the coolant system. I restored the rear heater and got the fan working. I removed the front heater today and began thinking about all the wasps nests that we, as FJ40 aficionados, have discovered and removed from the many vehicles we have collectively restored. After washing out the mud and flushing the coil I looked at all the space I gained under the dash and (considering it's 105F in my garage) thought about boxing up the heaters and enjoy the extra space. I don't see the point if I can easily delete them.

My question is can I just run a bypass hose from the lower heater port to the top of the block? From a coolant flow perspective it would be like the heater is always on, but is this in some way "bad" for the engine?

Second question is "should I" am I breaking an unwritten rule by removing the heaters? :)
 
105 in the garage here too. It is a great way to loose weight. I get the temptation to delete the heaters, I really do, but just wondering out loud how many well intentioned PO's started down the same path... ;)
 
a long bypass hose will work but for a permanaet delete a threaded plug in the head and a cap on the lower pipe - or the port-less pipe all together- would be best. The comment above is right- General Market trucks are set up that way from the factory. There are OEM parts to do this as well if you want to go that way.
 
I have seen 105 on my porch many times. Also seen -35 in my house for weeks at a time. When I was a kid in Az my dad would never turn on the heater in the car - I put a killer rear heater in mine, folks beg me to turn it off.

So one time I was cruising the tank trails after the spring thaw and rain. I was pushing greasy mud with the bottom of the hubs. I usually run an apron covering the bottom half of the radiator during winter. Any way it started to heat up, so I found a little down slope section, stopped, climbed out the window, down the hood and lowered the curtain to 1/4 of the bottom covered. Took back off and once again it was starting to run hot, this time I removed the curtain. It was better, but when I opened the back door and put the rear heater on full, then she ran right in the normal spot. This was all done in low range low and second. About 35 miles later when we came back out to the perimeter road I got a standing ovation from the National Guard boys for braving that mud bog.

Long story short, sometimes it pays to have heaters to help cool your engine - beats blowing a head gasket and then walking.
 
Last edited:
charliemeyer007 said:
I have seen 105 on my porch many times. Also seen -35 in my house for weeks at a time. When I was a kid in Az my dad would never turn on the heater in the car - I put a killer rear heater in mine, folks beg me to turn it off.

So one time I was cruising the tank trails after the spring thaw and rain. I was pushing greasy mud with the bottom of the hubs. I usually run an apron covering the bottom half of the radiator during winter. Any way it started to heat up, so I found a little down slope section, stopped, climbed out the window, down the hood and lowered the curtain to 1/4 of the bottom covered. Took back off and once again it was starting to run hot, this time I removed the curtain. It was better, but when I opened the back door and put the rear heater on full, then she ran right in the normal spot. This was all done in low range low and second. About 35 miles later when we came back out to the perimeter road I got a standing ovation from the National Guard boys for braving that mud bog.

Long story short, sometimes it pays to have heaters to help cool your engine - beats blowing a head gasket and the walking.
Click to expand...
So funny you should tell this story. I saved a head gasket, under much less perilous circumstances, when I was much younger. When I talked about removing the heater my wife reminded me of the story I had told her.

OK, I'll put it back in. If anyone asks me why I'll remind them that it got down to 5F in Austin...once...
 
I had a 1980 Corolla and a bitch of a wife. One Houston afternoon she stopped at a pay phone to call and tell me the car was running hot. 🥵 I convinced her to turn off the A/C and run the heater to cool down the motor. I smile now because I hated that woman.
 
hey peeps, new to the forum, not to hacking up vehicles.
I have been reading about the rear heater delete. being in Florida, i want to compeltey bypass all the heating system to avoid both unneeded heat in the cabin and any future leaks that might occur.
I found this thread to bypass the entire heating system.

It seems the prior owner already deleted the rear heater, so i had to watch videos to understand how the setups is originally.
I added a new radiator with electric fans, updated the hoses up front (1-3), thermostat and now the intake is off do to replace the two knock sensors (since i broke one removing the intake) , wiring harnesses for the same sensors and all the hoses that i can get my hands over this weekend.

I'm glad i found this so I dont get scolded for posting with searching!!

Regarding FULL bypass of heaters (front and rear) do i need to put a restrictor on the bypass hose?

I plan to connect to large nipple on head on driver side to the metal tube near firewall on the passenger side, and keep the hoses/alum tubing run within the engine compartment, never to enter the cabin. I'll be left with the 2 nipples on the firewall up top and two tubes lower on the firewall. (the rear is already deleted).

i wonder if some resriction is needed here due to the prior info i have read and pondered says there is some restriction of coolant flow to protect the heater core elements in cabin. my concern being that if i dont restrict the flow of this new route, will this change the flow in the head and cause overheating in the back of the engine?
I would imagine the coolant will rush to the path of least resistance and might take away from the head flow since the heater path likely offers resistance of flow.

if anyone has real world experience, i would love to hear it. I am still combing through you tube and i prefer to actually get the work done.
any advice would be appreciated.
 
You dont need any restrictions. Refer to @cruisermatt post #5. If you dont want to run the heaters remove them and just plug the ports as he describes. Put them in storage.
 
pb4ugo said:
You dont need any restrictions.
Click to expand...
thanks, for the reply.
I figure that is the route, will leave everything in place and cap all the nipples to avoid dirt. have installed a digital temp sensor to get an semi accurate ready and using obd2 bluetooth + app to monitor when i get this back on the road.

just heard that cylinder 6 could overheat if coolant didn't flow properly and that caused concern.
also read that coolant without going through heater and dissipating some heat, returns to other side too hot, causing potential overheating. i guess its a matter of overthinking, and need to just do it and monitor.

hot summers here and hauling boat during that time, need to stay as cool as possible.
 
Running the heaters increases coolant capacity which increases cooling if you open the heater control valve or remove it. 2f engines were put in forklifts and they dont have heaters.
 
How much useable space do you get taking out the heater? If you just shut the valve off on the block/firewall no hot coolant enters the cab.
We lost a space shuttle due to cold o-rings in Fl. Doesn't happen everyday. Never had a leak in the heater cores since I got the rig in 1982 - so guess leaks don't happen everyday.
 
pb4ugo said:
Running the heaters increases coolant capacity which increases cooling if you open the heater control valve or remove it.
Click to expand...
true! allows for dissipating heat. but it's hot as heck in the cabin, passenger really feels it. this vehicle does not have the heater control valve. goes from head to firewall nippe and out the other end back to engine.
hoping new radiator and electric fan setup make up for this delete. i am going to test it , i guess. and if an issue, easy to route back to nipple on firewall.
 
charliemeyer007 said:
How much useable space do you get taking out the heater? If you just shut the valve off on the block/firewall no hot coolant enters the cab.
We lost a space shuttle due to cold o-rings in Fl. Doesn't happen everyday. Never had a leak in the heater cores since I got the rig in 1982 - so guess leaks don't happen everyday.
Click to expand...
not interested in removing anything in the cabin except coolant flow and heat. would probably leave it all as is.
i watched videos and notced that i dont have that valve, mine was pumped directly from head to firewall nipple and back to the tubing that leads to the thermostat on the other side. rear heater host cut off and all those T's , etc. were already deleted.
EDIT: thanks for the reply!
 
tattoo80 said:
true! allows for dissipating heat. but it's hot as heck in the cabin, passenger really feels it. this vehicle does not have the heater control valve. goes from head to firewall nippe and out the other end back to engine.
hoping new radiator and electric fan setup make up for this delete. i am going to test it , i guess. and if an issue, easy to route back to nipple on firewall.
Click to expand...

Early 40's in stk form should have a manual shutoff valve at the head to stop coolant flow to the heaters. Later models had the heater control valves mounted on the firewall operated by a knob on the dash.
 
for the record, reason for delete is for wifey comfort (way too much heat on her side) and eliminate potential leaks in future since i am trying to get interior done soon. intake is all disasembled, so while i am there just figuring it all out.
there is no heater valve on this truck for some reason.
also thinking of routing the coolant bypass hose (smaller nipped on head near cylinder 5 and right next to that knock sensor) because it seems near impossible to get the clamp from head to under intake. will try to remove starter today to see, otherwise might route a hose from intake toward brake booster and another from head to booster area and then connect them there. not my first option, but i cant seem to reach way up under there. not sure why it was engineered that way.
*braces for comments bashing such an idea *
 
7AEA7113-209F-43E6-84B4-9C0213AA7F4C.webp
 
LC80sensor.webp


yes, you can see it here partially threaded in below the bypass nipple on left and the coolant nippe on right. 895615-30050

edit, 1997 LC 80
 
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