Rear Heater Bypass | Report & Questions

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Joined
Apr 6, 2019
Threads
5
Messages
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Location
Portland
Howdy,

I needed to tackle some deferred maintenance before a lengthy fly fishing road trip, and I found this mess under the truck. It's part of the rear heater lines and just one section that was completely deteriorating.
1987481


I’ve only had this truck for a few months after purchasing it from the original owner...an elderly lady that kept up on the normal things. Or things that were broken. But I keep finding some preventative stuff like this.

Anyway, this obviously looked like it was ready to fail any day now. And I don’t have time to hassle with the full rear heater line replacement so I ran the bypass. I picked up the molded bypass hose from a place called Land Cruiser Products - LCP. They sold a simple solution and thats what I was in the market for. :)

Started with this:
1987489


Ended with this:
1987490


Admittedly, it took way longer than I’d planned to get the old hoses out but the new hoses went in really easily.

Questions:
  • Do I need to disconnect the power to the rear heater?
  • If I leave it and run it, will it just circulate cabin air?
  • Should I do anything with the old coolant in the rear heater lines?
  • Regarding my red Napa auto parts hose...is this stuff junk? It was super cheap and also one of the only hoses I could find around town. I googled it but can’t find any info.
Thanks!
 
Last edited:
If you're going to leave the rear heater in the truck, There is a connector on the floor near it that you can disconnect, or disconnect the dash switch so no one could turn it on, or pull its fuse (if it is on its own, and will not kill anything else obviously). I would try and get the coolant out of it (maybe a necked down shop vac)? you could shoot compressed air into the end of a line, but that will get messy.
To get the hardlines out in one piece and install new ones, there is affair bit of stuff that has to get pulled. They are 1 piece molded lines that hug the floor pan and firewall.
No idea on the red napa hose.
 
Even though the rear heater won’t blow warm air while I’ve got the bypass in...and until I find time to do the full rear heater piping replacement, I like the idea of using it as a fan/blower.

Any harm running it while the coolant lines are bypassed?
 
I honestly have no idea. I think it should be fine as a "blower" only, but not sure.
 
You can run the blower. It is just a tiny radiator with a fan on it.

You could flush it with distilled water, then use compressed air to blow it out to dry it, then cap the line if you intend to use it again some day. However, leaving antifreeze in it will inhibit corrosion. It just won't be under pressure or risk you blowing line and overheating your engine.

The more I think about it, flush it with CLEAN antifreeze and cap the lines. That will inhibit corrosion and it will remove debris to make it better while it sits.
 
Howdy,

I needed to tackle some deferred maintenance before a lengthy fly fishing road trip, and I found this mess under the truck. It's part of the rear heater lines and just one section that was completely deteriorating.
View attachment 1987481

I’ve only had this truck for a few months after purchasing it from the original owner...an elderly lady that kept up on the normal things. Or things that were broken. But I keep finding some preventative stuff like this.

Anyway, this obviously looked like it was ready to fail any day now. And I don’t have time to hassle with the full rear heater line replacement so I ran the bypass. I picked up the molded bypass hose from a place called Land Cruiser Products - LCP. They sold a simple solution and thats what I was in the market for. :)

Started with this:
View attachment 1987489

Ended with this:
View attachment 1987490

Admittedly, it took way longer than I’d planned to get the old hoses out but the new hoses went in really easily.

Questions:
  • Do I need to disconnect the power to the rear heater?
  • If I leave it and run it, will it just circulate cabin air?
  • Should I do anything with the old coolant in the rear heater lines?
  • Regarding my red Napa auto parts hose...is this stuff junk? It was super cheap and also one of the only hoses I could find around town. I googled it but can’t find any info.
Thanks!

All hoses should be oem or Gates Green Stripe.
 

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