Pesky Heater Hose information on 1FZ-FE •  by Slee

Two photographs of the location of the small heater hose that is prone to leakage on 1FZ-FE Engines. Changing this hose causes some real headaches. Solutions we have heard from include removing the engine or refusing to do the work. The hose is located under the intake manifold on the rear of the engine. It connects the block to the heater system. The hose is in a high heat location and deteriorates faster that other hoses on the truck. If your truck has more than 60k miles on it, we recommend replacing it.

That is normally where the problem starts. It is very difficult to get to, however it is easier if you do it when you check the valve clearances. Access to the hose is easier with the valve cover removed. Here is an account from Robbie Antonson on fixing the little hose next to the road.

Hello Jeff:
I repaired this hose on the side of the road after it blew out when I was driving. It took me a little over two hour to repair. Not including a 2hour walk and cab ride to get back to the truck. Most of the problem is with the two bolts that hold the pipe to the intake manifold.

The lower of the two is the real bear. I used a 1/4 drive ratchet on the bolt with a big screw driver to pry the handle of the driver. Then my fat fingers were squeezed hard to move the driver back and forth to remove the nut. Another tool of reason that may work is the new end wrench with a ratchet in the box end.

After the pipe is loose then you can cut the hose by putting your hand through the opening between the body and the frame, after removing the tire ( I did it without removing the tire the first time). I then used the 1/4 drive ratchet to remove the hose on the head. The hose on the pipe is attached with the clamp style that has a band and cotter pin holding the band.

After cutting the new 5/8 Inch silicone heater hose (carquest) to the equal length of the two pieces I put a new clap on the pipe end and tightened it and put a new clamp on the how next to the other clamp and then slide the hose on the pipe on the head after putting the pipe back into the place it was before then hooking it back up to the heater valve on the fire wall. Then tighten the top 12mm head bolt into place and then tighten the hose clamps.

Fill with antifreeze and go. If you did not want to put this pipe back into place then run the heater hose (about 2 ft) from the head to the heater valve. Tighten securely and put rubber protection between the hose and any where you may put the hose up against to hold it down. I do hope this helps. Later Robbie in santa fe.

and another account from a reader.

Hi Christo,
I read the article on the heater hose in the tech zone last night and on your suggestion I replaced it today, I have 67,000 mile on my truck. I've read several posting on the web pertaining to this hose with solutions ranging from engine removal to intake removal to a two hour ordeal to get this hose swapped out. Because of the size of my hands removing the lower support bolt for the metal tube was not an option. As it turned out leaving this bolt alone was the best thing I could have done and thought I would share my procedure with you.

1. Drain antifreeze
2. Remove front left tire, and the middle and rear wheel well curtains.

Working from inside the wheel well:

3. Locate hose and either remove or relocate hose clamps up onto metal pipe
4. Cut off hose with a utility knife by cutting the hose length wise.

note: be careful not to damage the metal tube or block nipple.

Working from inside the engine compartment:

5. On the upper part of the tube remove the hose that attaches to the heater valve.
6. Remove the 12mm bolt from the upper bracket on the metal tube.

Working from inside the wheel well:

7. Rotate the metal tube and remove old clamps.
8. With the tube rotated push the new hose completely on the metal tube so the hose end is flush with the end of the metal tube.

note: the last 1/8" is a little tough because the hose is now bending around a curve in the pipe, I applied a liberal amount of spit to help it slide.
9. Place two new clamps over the new hose and up onto the metal tube.

Working from inside the engine compartment:

10. Replace the bolt into the tube's upper bracket and reattach the hose to the heater valve.

note: this should align the metal tube with the block's nipple
provided the hose is completely pushed onto the tube.

Working from inside the wheel well:

11. Using the flat side of a large screwdriver push the hose onto the block nipple.
12. Install clamps, curtains, tire and fill radiator.

Although it took me a few hours to work out this procedure knowing now what I do, I could do it in under an hour easily.

Thanks to the post on your site I know that I was able to avoid a road side repair as the hose was soft and swollen. Thanks again,
Rick Bigelow

and yet another one

My pesky little heater hose has been replaced. My scratches and bruises are still sore, but I think I can type. If you ever expect to have to do this repair yourself (i.e. Robbie Antonson isn't available), let me suggest you save these suggestions. They aren't perfect, but I can now give you a little more information than was available when I did this (my thanks to all of you who unknowingly helped out). FYI - when I refer to DS & PS, I am speaking of a LHD model.

One question before I go on. In doing this work on my truck I was forced to remove the Heater Inlet Pipe because I had bent the lower bracket and was unable to get the bolt back in. I have reassembled everything except that bolt, and am now wondering what consequence I'm going to pay for having it out. If anyone has an idea, please let me know.

I am not terribly proficient working on my truck. Yes, I've done the axle seal replacement, installed the TRD supercharger and measured my valve clearance, but I took longer than people are reporting to do every one of those. This is, to date, the hardest thing I have ever done on my truck. These parts are hard to see, hard to reach and they are in positions that rob you of most leverage. This is not a fun job, but it's easier to do in a good environment (like spring weather in your driveway) than it is a bad one (like on the side of the road, in 90 degree/90% humidity with a hot engine). Since this hose WILL eventually fail, do it before then. Mine lasted 113k miles.

First, the hose. The offending hose is 2.25" long, 5/8" I.D. and mine was 1" O.D. on the clamped ends, but 1 1/8" where it was swollen in the middle. I cannot comment on the best replacement hose. I don't know if heat, vibration or pressure is the biggest issue. Nobody has had a new hose in long enough to be able to say anything about the results.

To see the hose, remove the DS tire and remove the middle and rear skirts shielding the engine bay. Look up at the back of the intake header and you will see the pipe (it's black) coming down behind the header, making a couple of convoluted bends and going into the block right under the rearmost intake. You can just barely tell there is a coolant hose at this point. You can reach through this hole and touch it, but the larger your forearms are, the harder it's going to be. (I have a large bruise on my left forearm, roughly a foot from the tip of my finders, and multiple scratches further up).

You will be far better prepared for this job if you can visualize it. I have found the diagram in the factory manual that shows this part (you DO have a factory manual, don't you?). In my '96 LX450 manual it is on page EG-27, titled "Components for Disassembly and Assembly" (referring to the cylinder head). The problem part is called "Heater Inlet Pipe", and this metal pipe has the little coolant hose on the bottom where it connects to the engine block. Also notice the "EGR Pipe", you will find that pipe runs slightly behind and to the PS of the Heater Inlet Pipe, causing you great frustration trying to reach the lower of the two brackets.

Those two brackets will prove to be important. The higher bracket is very easily located. It is on the very top of the back of the engine and can easily be unbolted from the PS of the truck. The bolt goes in from the side, so removing it allows you to pivot the top end of the pipe side-to-side. The lower bracket is the hard one. It is on the back of the block, halfway between the first bracket and the bottom of the pipe. The bolt on this one goes in from the back, so you are very restricted in space. I suggest you use a tool I found at Sears (after I was done %$#@%$!!!) called the GearWrench ( and search for 00942001000) It looks like a regular combination wrench, but the box end is a ratchet. It will allow movements as small as 5 degrees, and you don't have considerably more than that to work with. The only way I was able to reach this bolt was to remove the valve cover, but Robbie can somehow manage with it still on (note he prefers it be off as well).

I strongly suggest you replace this little hose at the same time you have the valve cover removed. The GearWrench _might_ allow you to access the bolt without removing the valve cover. It's worth a try, so someone please report back when you do try.

The top of the Heater Inlet Pipe connects to a part called the "Heater Valve" by way of a short "Heater Hose". These are pictured in my manual on page EG-16, titled "Cylinder Head Components for Removal and Installation".

Now, the easiest way to replace this hose (but I consider it an emergency repair) would be to run a 5/8" hose from the block nipple to the heater valve. You could do this by:

1) Removing the top bracket bolt from the Heater Inlet Pipe and removing the hose elbow between the Heater Inlet Pipe and the Heater Valve.

2) Cut the problem hose in half, wiggle the Heater Inlet Pipe out of the way and remove the clamp and hose section from the engine nipple.

3) Clamp the new hose to the Heater Valve on top and the engine nipple on bottom. (Both of those clamps could be used from the existing hoses and this shouldn't take very long at all)

But this leaves a couple feet or so of coolant hose in a very hot, vibration-prone position. You would still need to make a permanent fix. To do that I am going to assume you have removed the valve cover.

1) Remove the top bracket bolt from the Heater Inlet Pipe and disconnect the hose connecting it to the Heater Valve as previously discussed.

2) Reach down behind the engine with the tool of your choice and loosen the bolt holding the lower bracket but DO NOT LET THIS BOLT COME OUT UNLESS YOU DON'T PLAN ON REPLACING IT.

3) Access the lower end of the Heater Inlet Pipe from the wheel well. Using pliers of some sort, loosen the cotter pin clamp holding the coolant hose to the pipe. After it is loose, cut through the clamp with side cut pliers.

4) Now use pliers to move the traditional clamp up onto the Heater Inlet Pipe and cut the problem hose lengthwise with a knife and remove it.

5) Put the two clamps (one will be new) for the coolant hose on the Heater Inlet Pipe. Lube the inside of the new coolant hose and slide it onto the Heater Inlet Pipe (BE VERY SURE YOU DON'T BEND THE PIPE BRACKETS. Use something behind the pipe to restrict its movement or you will be forced to remove it for straightening.)

6) Tighten the Heater Inlet Pipe brackets and then slide the coolant hose over onto the engine block nipple.

7) Move the clamps into position and tighten down the new hose.

8) Replace the heater hose between the Heater Inlet Pipe and Heater Valve.

9) Replace everything you removed to do the work (wheel well skirts, valve cover, etc.), fill with coolant and you're ready to roll.

I know this sounds simple. It even looks pretty simple when you first look at it. Take your time and it can be done. You will be able to do it much faster the second time - there's a lot of benefit to experience with this one.

Standard Disclaimer - I've never met Robbie Antonson, and I don't know what he charges to do this job on a truck, but it is worth every penny of your money to let him do it. It really is a pain in the butt.

Good luck,

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I say that it would be very unlikely anything would be different between model Sears when it comes to something of this nature. It would have to be a different casting on the cylinder head. One of the things that I did to make life easier was when I removed the tire I also lowered the vehicle on the jack so that I didn't have to strain as much reaching up under there. I just sat my butt on the ground with my legs scooted under the truck. Make sure it is still supported by more than the jack before doing something stupid like that.

First I was only using my right hand. I had also loosened up the transmission dipstick and brake line mountings to allow more room under there. Just start out at the hose and traverse by touch until you find the mounting point. Once I was comfortable with where it was located I then put the bolt between my middle and index fingers got it in place then just tightened it with my index finger. Takes a bit of control with the digits (YHSMV - your hand size my vary).

Phil Postmus
Supercharged 94 FZJ80
Franklin, TN. USA

Heater hose location. This photo was taken with the motor out of the engine bay. The rear of the motor is to the right

Access through driver side wheel well. Highlighted area shows approximate location of detail photo.

Detailed photo showing hose removed from connector on head.

Heater Hose outlet on block

Heater Hose shown from the rear of the motor

Heater Hose Detail

Heater Hose showing signs of leakage and bulging

Sludge build-up in radiator