Replacing rear heater hard coolant lines

kbellve

 
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May 30, 2005
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Hubbardston, MA
The front hard coolant lines to the rear heater failed on my 1996 LX450 leaving coolant all over the ground. I replaced the rear section of the hard coolant lines, which was easy enough, but I see no way to replace the front lines that go between the frame rail and the bodypan and then over the transmission and then behind the head.

Either I have to pull the engine forward 4-5 inches, or lift the body off the frame. I can't find a method in the FSM to change this line. I have the replacement line, and I don't just want to patch the current line since it will fail somewhere else.

You would think they would do a better job of corrosion protection on these lines. My 1985 4Runner also had these lines rust through.

Any ideas how to replace the lines?

BTW, this engine blew its HG at 90,000. Lexus would do nothing to help fix it. The truck has 130,000 miles now on the replacement HG. The replacement HG may have failed again due to the rapid loss of coolant.
 

powderpig

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I have often wondered how to remove these line if needed. You are the unlucky one to blaze the trail on this one. I can not remember any one haveing to replace these lines. What part of the country do you live in? I know it may be coming into winter, but have you thought about just bypassing the loop for now while you figure out how to remove these lines? this way you cold drive the truck until you have finished the project. I will look at my cruiser today to see what I can see. It is a 93, maybe it will be close enough. good luck robbie
 

kbellve

 
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May 30, 2005
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Hubbardston, MA
yea..I have it bypassed at the moment...It doesn't look pretty. I have removed the 3 bolts holding the line in...but that is as far as I have gotten....my next step is to see how hard it is to move the engine 3-4 inches forward...

I live in Massachusetts.
 

powderpig

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Figures, east coast snow belt, lots of salt. If you are going to move the engine forward, I would pull the fan, remove the radiator(for protection of the radiator). Un do the fuel line at the filter, loosen all the wire harness, remove the air hose from the air box(may be remove the box for protection and space), remove some of the ground wire to the intake manifold, ground wire at the back of the head, remove the wire between the distributor to coil. I would also just unhook the computer inside the dash and pull the main wires out. You may also have to un hook the wires that go to the O2 senser. Remove the drive lines to the diffs, remove the transmission mount and support the tranny with a jack. Undo the Motor mounts at the frame, I would also remove the hood(give more room for the cherry picker or fork lift). Un hook the exhaust at the manifolds. You may then be able to pull up and forward at the same time to get acess to the pipes. good luck robbie ty
 
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I have a set of those lines hanging on the wall of my garage. They've been there for about 4 years. When Mine started to leak I bought the pipes and then when they arrived I looked at fitting them. My conclusion at the time was "square peg round hole" unless I was willing to do alot of work (moving engine etc.)

I cut the hard lines in the area of the leak and added another section of rubber line. Works fine for me......I recall the frustration I had when I noticed my coolant leak. It wasn't enough to drip on the ground....took me awhile to finally find the source of the leak....Good luck....
 
Joined
Oct 26, 2004
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Michigan
Just cut the metal lines somewhere in the transmission tunnel and route heater hose all the way back to the rear heater core. You can leave the old metal lines right where they are. You would have to remove the cat. heat shield to get them out anyway. The new rubber lines tusk in nicely on top of the frame. If you are worried about chaffing, run the rubber hose through a length of pvc pipe. Most aftermarket, and OEM, rear heaters run rubber all the way back. I double clamped everywhere when I did this. You can carry a piece of the old pipe in your glove box if you are worried about springing a leak.....just splice in the piece of pipe until you can go out and buy $3.00 worth of heater hose to redo the job. I bet this fix will last many years. It is so cheap and easy you could replace the rubber everytime you flush the coolant.
Good luck
 

IdahoDoug

 
 
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Aug 9, 2003
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I just went out to the garage where my headless 80 is sitting at the moment and it looks like those lines could be replaced with the head off. They can be slid forward quite a ways easily once disconnected since they come into the engine bay right at the level of the top of the block, and you can rotate them at the same time since there's nothing in the way.

I'm not suggesting pulling the head as a happy solution, but frankly sliding the engine forward sounds like 50% of the work of pulling the head and you get no additional benefits. Plus, you may still not be able to get those pipes off. With the head, you get a coolant flush, new gaskets, a clean throttle body, great time to change the fuel filter, alternator brushes, new hoses at the firewall and heater valve, etc, etc.

If this appeals, I'll take a closer look and do some measurements on Sunday.

DougM
 
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Mar 27, 2003
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I looked at those lines when the motor was out but didn't replace them. I would do as advised above and just bypass them with heater hose.
 
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IdahoDoug said:
I just went out to the garage where my headless 80 is sitting at the moment and it looks like those lines could be replaced with the head off. They can be slid forward quite a ways easily once disconnected since they come into the engine bay right at the level of the top of the block, and you can rotate them at the same time since there's nothing in the way.

I'm not suggesting pulling the head as a happy solution, but frankly sliding the engine forward sounds like 50% of the work of pulling the head and you get no additional benefits. Plus, you may still not be able to get those pipes off. With the head, you get a coolant flush, new gaskets, a clean throttle body, great time to change the fuel filter, alternator brushes, new hoses at the firewall and heater valve, etc, etc.

If this appeals, I'll take a closer look and do some measurements on Sunday.

DougM
Doug take advantaqge and if you're hard lines are suspect seems like now would be a good times to replace them.
 

kbellve

 
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May 30, 2005
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Hubbardston, MA
mine looked fine too along the firewall.

They fail where the lines go over the frame. Check where the lines are bolted, and see if there is corrosion near those spots.
 
Joined
Apr 13, 2012
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Greensburg PA.
Sorry guys, I'm reviving this thread. I'm planning on removing those rear hard heater lines tomorrow. I wasn't able to finish the job tonight as I wasn't sure how to go about removing these lines.
I'm not interested in replacing the hard lines with new ones, I just want to remove the hard lines. So I can cut these hard lines anywhere I want and rip them out., but it even looks kinda tough doing that.
So anyone have a specific way they have done this? I want them removed because I dont want them in the way when I have future projects where I might need the space to wrench back there. Thanks guys, Tyler.
 
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Oh also I'm thinking that I will cut the pipes as far up under near the transmission as possible and ripping the hard lines up through the hood behind the valve cover. But another part of me says that pulling them down from under the car would work better.
I'm also planning on keeping my rear heater operational when I eventually add back some rubber or silicon lines along side the frame rails.
 
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I just cut mine by lower firewall and ran silicone hose up inside frame rail connecting to the rear heater. I left the old pieces in the truck. No harm in just abandoning them. Has worked great for me for couple yrs.
 
Last edited:
Joined
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I just cut mine by lower firewall and ran silicone hose up inside frame rail. I left the old pieces in the truck. No harm in just abandoning them. Has worked great for me for couple yrs.
Ya I was thinking a lot of people were doing that, but my ocd makes me want the old lines gone.
No ones completely removed them?
 
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I am a weee bit OCD too but sometimes you just have to tell yourself not to stress about it. The lines do no harm still in there. Just looks like you still have bad lines but who cares really.
 
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Hey, so just wanted to let you guys know I did leave the rear heater hard lines in place. I think that it will be much easier to remove them if I ever get around to doing a head gasket pm or something more involved than just a simple coolant flush and rear heater bypass.
 

jfz80

 
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Jun 5, 2005
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Madison NC
If you wan to read up before then to prep for their removal try searching for a post or thread by Landtank and heater lines. He was able to replace them but not easy. I believe he also divorced the two new lines and also may have loosened motor mounts and lowered the tail end of transmission for more room.

Mine sit in place unused as scrowleys do.
 
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