Emergency heat bypass (1 Viewer)

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Feb 12, 2015
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Plano, TX
I put a new radiator cap and overflow bottle on 2 days ago, because they were original and I was getting a little leak around the overflow nipple and the radiator cap seals were crusty. All OEM from TPD.

I drove about 30 miles today and I got to my friends house and there was a flood of coolant coming from my rear heater.

I’m hot and tired and just want to limp the truck home and deal with this later...

How can I bypass both heater cores, the heater control valve, etc. - ALL of it so I can drive home and assess the damage?

So weird it starts leaking two days after a new cap.
 
Joined
Apr 16, 2006
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HI
If you're trying to bypass the all heaters, it look something like this.
Find some gates heater hose, and connect.

Just be aware that if you don't burp the system, there's a chance you'll overheat, because you can't use the heaters to expel excess heat.


*Second image modified from wits end site

1994SALVAGE80LXENGINE.jpg


Wits-End-1FZ-Rear-Heater-Bypass 3.jpg
 
Joined
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Messages
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Location
Plano, TX
Is the 3FE heater routing the same as a 1FZ?
The OP doesn't say what he's driving, but maybe it doesn't matter?
I was a bit in the weeds when I posted this...1997 1FZ.

Sorry for the vagueness of the post.


If you're trying to bypass the all heaters, it look something like this.
Find some gates heater hose, and connect.

Just be aware that if you don't burp the system, there's a chance you'll overheat, because you can't use the heaters to expel excess heat.


*Second image modified from wits end site

View attachment 2663337

View attachment 2663338

This is super helpful! Another question, and only because I’m curious, which direction does the coolant flow?
 
Joined
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Plano, TX
After I had my buddy run me up to the auto parts store and grab some 5/8 Gates heater hose, various clamps, coolant, etc. - I climbed underneath and noticed that the clamps and connecting the hose to the rear heater matrix weren’t seated properly and the hoses weren’t positioned correctly between the hard pipe and the rear heater.

Not wanting to shatter my heater valve and cause a worse problem, I just re-positioned those clamps, which slowed the waterfall down to a steady, slow drip, I added a zip tie and limped it home.

I guess the questions I have now 1) should I bypass/delete this permanently? 2) if so, how permanently? 3) if not, should I go back with stock rubber, silicone hoses, a bunch of Gates hose and Breeze clamps, or what? What’s the hive mind doing for their rear heater issues?

Thanks for the help. At least we are both home in one piece.

059F9867-57C4-4741-85B7-2A6E5A917A63.jpeg
 
Joined
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I replaced those rear heater hose lines about 5 years ago with Gates 5/8" heater hose and the same type of constant tension clamps you have there. I remember that it seemed like there was barely enough hard pipe sticking out to get a good seat on the hose and have the clamp sit over the hard pipe section. I like things to be stock, and I like the extra fluid volume for keeping things running cool, so if it were me I'd take another crack at getting those hose to seal up there.
Maybe your clamps are a hair too big, or you didn't get the hose seated far enough? I'm glad you got it home, and at least now you know where your problem is and it's not leaking so fast. Good luck, let us know what you end up doing.
 
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I replaced those rear heater hose lines about 5 years ago with Gates 5/8" heater hose and the same type of constant tension clamps you have there. I remember that it seemed like there was barely enough hard pipe sticking out to get a good seat on the hose and have the clamp sit over the hard pipe section. I like things to be stock, and I like the extra fluid volume for keeping things running cool, so if it were me I'd take another crack at getting those hose to seal up there.
Maybe your clamps are a hair too big, or you didn't get the hose seated far enough? I'm glad you got it home, and at least now you know where your problem is and it's not leaking so fast. Good luck, let us know what you end up doing.
Thanks for your perspective - I’m leaning towards refreshing all of the hoses with Gates hose and new clamps, like you suggest here. They look original - yikes.

Great news though - the hard pipes look to be in excellent shape! Still factory black and not crusty.
 
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That's good news about your pipes looking good, all the more reason to keep them in service. I found that if they get a little ovalized during R&R, you can gently work them back to round with something like a socket just smaller than the pipe, just put it on an extension and exert a little force from the inside. They can be massaged a bit so they look perfectly round before you slide the new hose on. Gravity is working in your favor there such that if the socket were to pop off it would just drop out of the pipe and into your hand. Good luck.
 
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As mentioned above be gentle if removing old hoses from either heater core. The pipes are thin brass and can be deformed by yanking on the hoses. FWIW
 
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I replaced those rear heater hose lines about 5 years ago with Gates 5/8" heater hose and the same type of constant tension clamps you have there. I remember that it seemed like there was barely enough hard pipe sticking out to get a good seat on the hose and have the clamp sit over the hard pipe section. I like things to be stock, and I like the extra fluid volume for keeping things running cool, so if it were me I'd take another crack at getting those hose to seal up there.
Maybe your clamps are a hair too big, or you didn't get the hose seated far enough? I'm glad you got it home, and at least now you know where your problem is and it's not leaking so fast. Good luck, let us know what you end up doing.
One more question - how much coolant should I anticipate trying to catch when removing the soft hoses connecting the hard pipe to the rear heater core?

I’ll probably not reuse the coolant, I just want to be prepared for how much is going to pour out, and also have enough coolant on hand to replace it.
 
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If I told you I knew, I'd be lying. It *seems to me* that those hard lines are the low point from the heater control valve back, so it's not like you're going to get coolant from the block or radiator draining way back out there. Also, I'd close the heater control valve (put the slide switch in the controls to full cold) all the way to ensure that you aren't going to lose fluid from the heater control valve forward anyway.
 
Joined
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Messages
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I replaced those rear heater hose lines about 5 years ago with Gates 5/8" heater hose and the same type of constant tension clamps you have there. I remember that it seemed like there was barely enough hard pipe sticking out to get a good seat on the hose and have the clamp sit over the hard pipe section. I like things to be stock, and I like the extra fluid volume for keeping things running cool, so if it were me I'd take another crack at getting those hose to seal up there.
Maybe your clamps are a hair too big, or you didn't get the hose seated far enough? I'm glad you got it home, and at least now you know where your problem is and it's not leaking so fast. Good luck, let us know what you end up doing.
I am rather embarrassed to admit that my Cruiser mostly sat for the past 30+ days while I hashed my way through some work stuff and home DIY that was long overdue, but now I am back to this problem because I am itching to drive her.

I parked it last night up on some ramps to give myself a little more room and to make sure I was working on a completely cold system. I went out there to measure the hoses and clamps again and I am a little concerned - the hard pipes measure 14mm exactly in OD, which is far enough off from 5/8" that I am pausing to verify and ask the IH8MUD hive mind - is this worth trying to wait for OE hoses or trying to find some metric hoses, OR, is that little flare at the end of each hard pipe large enough to make the 5/8" hose a nice, snug fit? I am assuming I am being overly cautious because @bicycleagent003 said he used Gates 5/8" some 5+ years ago and they are holding strong.

Based on the conversion chart below, I am concerned enough to stop and ask. Always easier to ask twice than to go back in time. ;)
  • 14mm = almost 9/16 inch
  • 15mm = almost 19/32 inch
  • 16mm = 5/8 inch
Lastly, is there any trick to remove the cotter keyed clamps gently? See the image of what I am referring below:

IMG_2336.jpeg
 
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I am rather embarrassed to admit that my Cruiser mostly sat for the past 30+ days while I hashed my way through some work stuff and home DIY that was long overdue, but now I am back to this problem because I am itching to drive her.

I parked it last night up on some ramps to give myself a little more room and to make sure I was working on a completely cold system. I went out there to measure the hoses and clamps again and I am a little concerned - the hard pipes measure 14mm exactly in OD, which is far enough off from 5/8" that I am pausing to verify and ask the IH8MUD hive mind - is this worth trying to wait for OE hoses or trying to find some metric hoses, OR, is that little flare at the end of each hard pipe large enough to make the 5/8" hose a nice, snug fit? I am assuming I am being overly cautious because @bicycleagent003 said he used Gates 5/8" some 5+ years ago and they are holding strong.

Based on the conversion chart below, I am concerned enough to stop and ask. Always easier to ask twice than to go back in time. ;)
  • 14mm = almost 9/16 inch
  • 15mm = almost 19/32 inch
  • 16mm = 5/8 inch
Lastly, is there any trick to remove the cotter keyed clamps gently? See the image of what I am referring below:

View attachment 2700005
Most people use a pair of dykes to cut the band on the cotter pin clamps.

There is also a "cotter pin puller" tool with a hook on one end and a screwdriver type handle that you can use to hook it from the open end and twist and pull to release. That's been on there for 25+ years and may not be happy about moving.

The dykes would probably be the "most forgiving".

I would also be concerned about sliding a 5/8" hose over a 14mm tube. Get online and check the hose manufacturer specs.

Most specify the Gates Green Stripe hose, which is a heavy wall hose and may have tighter tolerances (smaller ID)

Otherwise, to change back to OEM, you need the hard lines and where they go over the transmission, you cannot get them out without dropping the trans so everyone says. The OEM stuff comes with the hoses pre-attached.
 

davidp14

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I recently deleted my rear heater completely.
I used the one piece hose from LCP and I replaced my HCV at the same time, as well as the right side hose that goes on the other side of the HCV.

There's more coolant in those hoses under the rear heater than you think. I spent a long time laying under the truck with rags held up against the outlet. If I did it again Id cut the lines and place a pan underneath, then go complete step #6. There is not much coolant in the hoses in the engine bay, less than a quart.

Cut the sardine can clamps off, don't bother trying to save them.
 
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Messages
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I am rather embarrassed to admit that my Cruiser mostly sat for the past 30+ days while I hashed my way through some work stuff and home DIY that was long overdue, but now I am back to this problem because I am itching to drive her.

I parked it last night up on some ramps to give myself a little more room and to make sure I was working on a completely cold system. I went out there to measure the hoses and clamps again and I am a little concerned - the hard pipes measure 14mm exactly in OD, which is far enough off from 5/8" that I am pausing to verify and ask the IH8MUD hive mind - is this worth trying to wait for OE hoses or trying to find some metric hoses, OR, is that little flare at the end of each hard pipe large enough to make the 5/8" hose a nice, snug fit? I am assuming I am being overly cautious because @bicycleagent003 said he used Gates 5/8" some 5+ years ago and they are holding strong.

Based on the conversion chart below, I am concerned enough to stop and ask. Always easier to ask twice than to go back in time. ;)
  • 14mm = almost 9/16 inch
  • 15mm = almost 19/32 inch
  • 16mm = 5/8 inch
Lastly, is there any trick to remove the cotter keyed clamps gently? See the image of what I am referring below:

View attachment 2700005

I found the 5/8" Gates Green Stripe worked fine and was not terrible to get on the hard pipes. As I recall, I used some lube (yes, that lube) to put the hoses on. My thinking was that lube's water soluble, and it's not as drippy as water so it stays on better for installation. So, yes, I'm actually talking about sex lube, specifically the CVS version of AstroGlide Liquid. (Probably the first time that has been mentioned on Mud.)
I just put some on the inside of the hose and some on the pipe, and they went right on, as I recall. Not that it was easy, there is precious little room to work in there and the pipes don't stick out much. But that 5/8" Gates Green Stripe worked fine for me.

I really like these clamps, though sometimes you have to order a couple different sizes to get the one you want. I know I had to.
Amazon product
And I find this tool invaluable, particularly in tight spots like the rear heater lines and the firewall heater hoses. I could not have done either job without these:
Amazon product
It's not a hard job, just a little tedious and your arms get tired. If you have gorilla size hands or wrists it will be harder.
I sure someone would install a work shed with a lift in it at at my house... I'm getting tired of rolling around on my driveway...
 
Joined
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Plano, TX
Welp…the lines are off, the copper tubes going in/out of the rear heater matrix are ovaled, even though I didn’t use a tool on them, which sucks.

BUT, she’s dead where she sits…5/8” is so loose it just slips on and off easily with no resistance and the 1/2” hose I got it too small and I don’t want to force it on there and bend/break anything else.

If I wasn’t worried about shattering my heater valve, I would just bypass it all.
This really was an awful idea.
 
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Jun 25, 2012
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Delburne, Alberta
If you need a right now solution to make truck driveable you can connect rear heater hoses together forming a loop to bypass rear circuit. Use whatever you can find to act in place as a double ended hose barb, and clamp away. Piece of copper pipe, a socket you can get both hoses over, whatever youve got. Alternatively can stick a solid object such as a suitably size bolt in either end and clamp to keep coolant in.
 
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Also nothing to lose trying the 5/8th hose youve got with decent clamps or even try two clamps per joint, doesn't have to be perfect. Lots of give with rubber hose. Try not to overthink it. Remember, its a Landcruiser, not a spaceship.
 
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Also nothing to lose trying the 5/8th hose youve got with decent clamps or even try two clamps per joint, doesn't have to be perfect. Lots of give with rubber hose. Try not to overthink it. Remember, its a Landcruiser, not a spaceship.

Yeah, my panic and frustration was just because everything was about to close for the evening. I grabbed a long piece of pre-formed 9/16” heater hose as a wild shot.

I can cobble it together long enough to move it out of the way, but I was reallllllly hoping this was gonna be a one and done. My perfectionism is driven by a desire to do every job once and only once, but at 10:30 at night, my position has changed to the “whatever works for right now” solution is the best solution.

Also, I hope this thread is helpful to others. Don’t do what I did! ;)
 

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