2001 4.7 Heater Hose Slow Leak - JeepForum.com
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post #1 of 18 Old 05-18-2020, 02:14 PM Thread Starter
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2001 4.7 Heater Hose Slow Leak

I haven't posted in a long time, but have a question about which heater hose is the inlet and which is the outlet for the 4.7. I have a 2001 4.7 parts list here and it shows the the lower one on the thermostat housing as the supply, and the upper is the return.

I found another water flow diagram on the internet which looks legit showing the lower one is coming from the heater core and the upper is going to the core which seems opposite of the parts diagram.

On mine the hose that is leaking is the lower one on the thermostat housing and runs outboard and lower than the other heater hose to the rear. The leak is where the rubber connects to the metal tube on the rear side. I can't order the part till I know for sure which is which.

The hose only leaks at very close to the maximum 18lbs of pressure. I thought about running a lower pressure cap, but in the desert heat, I doubt this would be a good idea.

As an aside for the old-timers: Do any of you remember the thread that had a link to a 2001 WJ service manual in it? I downloaded the manual years ago, but can't remember the password that was also posted in the thread. I used to just search and it would come right up, but can't find it now. If I could get into the manual, I could probably answer my own question.


2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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post #2 of 18 Old 05-18-2020, 02:32 PM
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From the documentation I have:

At the thermostat, the lower hose is labeled "supply". It has a Mopar part number of 55115895AB. It appears to enter the firewall as the higher of the two hoses.
At the thermostat, the upper hose is labeled "return". It has a Mopar part number of 55115896AB. It appears to enter the firewall as the lower of the two hoses.

Apparently, the rubber only portions of each assembly are available as aftermarket parts. That strongly implies that you should be able to re-use the pipe portion of the assemblies with a crimp or clamp of your choosing. I believe there was a post here a while ago by someone who did just that. There are also all silicone hoses that look like a superior option but they are pricey (though not much more if anything than the OE hose assemblies).

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post #3 of 18 Old 05-19-2020, 11:46 AM Thread Starter
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Quote:
Originally Posted by 99wjtx View Post
From the documentation I have:

At the thermostat, the lower hose is labeled "supply". It has a Mopar part number of 55115895AB. It appears to enter the firewall as the higher of the two hoses.
At the thermostat, the upper hose is labeled "return". It has a Mopar part number of 55115896AB. It appears to enter the firewall as the lower of the two hoses.

Apparently, the rubber only portions of each assembly are available as aftermarket parts. That strongly implies that you should be able to re-use the pipe portion of the assemblies with a crimp or clamp of your choosing. I believe there was a post here a while ago by someone who did just that. There are also all silicone hoses that look like a superior option but they are pricey (though not much more if anything than the OE hose assemblies).
Your information matches the parts list I have. The one leaking on my Jeep is the supply line which I am going to assume is the inlet. The parts houses only say inlet or outlet on their part descriptions. I don't want to overthink it, but is it inlet/outlet with reference to the thermostat housing or the firewall? If only I hadn't found a 4.7 water flow diagram opposite of the parts list descriptions, I wouldn't be scratching my head.

2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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post #4 of 18 Old 05-19-2020, 12:32 PM Thread Starter
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I went ahead and ordered a Dorman part no. 626-590 heater hose assembly which they refer to as the inlet. I normally get my parts from Napa, but I can get the Dorman today. FYI for anyone reading this thread, Napa has the Zerex G-05 on sale this month. I picked up several gallons of the 50/50 for 11.99 each, the cheapest I've ever seen it. The concentrate is 13.99.

2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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post #5 of 18 Old 05-19-2020, 01:35 PM
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Being a loop I'm not so sure it matters on the WJ (no coolant valve for instance) but I'm guessing that inlet and outlet would be from the perspective of the thermostat. It shouldn't matter, that is, unless maybe one way creates less cavitation than another.

In fact, swapping the hoses around at the firewall every several years may be a beneficial way of keeping the core free-flowing. My heater core is partially clogged and leaking intermittently and ever so slightly in one of my WJs. I may try swapping the hoses around at some point to see if it helps with the clog.

Rage! Rage against the dying of the Jeep.

99 WJ Limited 4.7/NV247
01 WJ Laredo 4.7/NP242
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post #6 of 18 Old 05-19-2020, 05:58 PM
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I think you want the inlet to the heater core connected on the lower barb.
If not, you may get air trapped in the core.

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post #7 of 18 Old 05-25-2020, 01:27 PM Thread Starter
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Well, for the first time in 45 years of repairing my own vehicles, I have reached a brick wall. I am unable with the tools I have to get the clamp loosened on the firewall end. The previous owner of the Jeep had the heater core replaced and they used worm clamps instead of the spring clamps Mopar uses. I have tried everything I have, and can't get a good hold on the nut. I'm out of time due to moving and need to drive this Jeep 1300 miles. So, I have a question for the more experienced. It doesn't leak until the pressure exceeds 16lbs. So What kind of problems might I expect to have, if I run a 15lb or 16lb cap?? I would most likely get a 16lb. and it only has to get me there.

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post #8 of 18 Old 05-27-2020, 01:03 AM
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If the cap pop off pressure is to low, it will push coolant out of the engine and either overfill the overflow tank, or blow it right past the cap itself. Either way, I think you might have trouble keeping the coolant in there, and we all know what happens when an air bubble gets left in the system......See dropped valve seat sticky....


Can you get into that hose clamp with just a bare hacksaw blade? I know it kinda sucks, but i have cut things off in the past with just a hacksaw blade in my hand. Its better than nothing?

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post #9 of 18 Old 05-27-2020, 05:22 AM
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The coolant enters the heater core on the lower inlet tube - as for the hoses at engine see attachment. Follow the arrows as the to and from are not showing a pointer.
Attached Images
 

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #10 of 18 Old 05-27-2020, 11:05 AM
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It may be too late chalkboard if you've already left on your trip. While you may not have one a Dremel or rotary cutting tool with a small round metal cutting disk would likely make short work of that worm clamp stuck on your hose. Of course you'd have to have a steady hand while not cutting into anything else. Cutting a little into the hose wouldn't matter since you have a new one but sure wouldn't want to cut into the heater core tube.

I know it's a tight fit in there next to the firewall but I've had my Dremel into some pretty tight places. Just a thought if you could borrow one and maybe the part stores have loaner ones. Good luck.
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post #11 of 18 Old 05-30-2020, 10:31 AM Thread Starter
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I appreciate all the comments and suggestions. I have not started my move yet, but am out of time to devote to the leak which I may have made worse by fiddling with it. I would like to mention I received a suggestion to be used as a temporary repair from another source (my dad) I thought was good, and that was to cut the rubber hose in the back right in the middle, and then cut the new one in the same place, and use a brass barbed fitting with clamps to connect the new to the old.

With what little time I have left, I have to get the HVAC working again since the lady of the house will be driving it during the move. My problem is my fresh air/recirc flap broke loose some time back and is sitting on top of my blower motor blocking all of the air flow. I have already tried using an old wire coat hanger with spring tension to hold the flap on the fresh air side, but misjudged how the far fan cage enters that space. So I am going to get in there again, but push it against the recirc side instead. I think I would rather have it locked on fresh air intake only anyway.

2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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post #12 of 18 Old 05-31-2020, 01:02 AM
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I almost posted on here yesterday after looking at my 04 4.7 heater hoses where they attach to the core at the firewall. What a friggin' nightmare to get to those hoses clear back in there on the core especially if you have a stripped band clamp on the bottom hose like you do! Main wire harness in the way, AC lines going to expansion valve real close, valve cover sticking out, etc.. Can sympathize with you.

I know I'll eventually be pulling the whole HVAC box and replace about everything including an evaporator with a minor leak, heater core, doors, actuators, etc.. To even get to those core hoses I might as well replace my leaking valve cover gasket on the passenger side to get a little more room to those core hoses. Fun...

I had to read your thread again because I thought your leak was on a core hose and that way you could for now just create a new hose loop from the 2 tubes on the timing chain cover and leave the heater core idle while plugging the hoses temporarily . But with a leak at the thermostat tube that's a real good idea your dad has to install a new hose where it's leaking and cut/splice it to the existing hose on the core in the middle where it's easy to get to.

Those heater hoses aren't very big ID and believe they're .62". That was off a spec off a replacement hose for my 04 4.7. And when I measured the OD with a micrometer yesterday it was 7/8" OD on the OE heater hoses. Of course you'd need a little bigger clamp with a coupling or fitting tube shoved in the hose.

If you're going to permanently or for now place your recirc door in one position believe I'd have it on recirculate. In other words have it open to the inside cabin and block the outside air. The main reason for saying this is you live in Vegas don't you and your wife is going to be driving your WJ? I don't know if I'd want 100+ degree outside Vegas air mixing with the AC air while trying to cool down the cabin. Fresh air is nice but it's a lot more efficient to have the half-cool cabin air entering the HVAC system rather than real hot air. Just my take before you hear it from "The Hammer". :-)

There's a little bit of good info on the recirc door positions in the below blendorstore tech tips at the end.

http://blendorstore.com/tech_tips

Pinning that door open or shut isn't much different with their kit than you tried with coat hangers. I think I even remember somebody installing a screw in one of the upper door corners to pin it to the housing away from the cabin. Good luck.

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post #13 of 18 Old 06-01-2020, 08:51 AM Thread Starter
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Quote:
Originally Posted by Uniblurb View Post
I almost posted on here yesterday after looking at my 04 4.7 heater hoses where they attach to the core at the firewall. What a friggin' nightmare to get to those hoses clear back in there on the core especially if you have a stripped band clamp on the bottom hose like you do! Main wire harness in the way, AC lines going to expansion valve real close, valve cover sticking out, etc.. Can sympathize with you.

I know I'll eventually be pulling the whole HVAC box and replace about everything including an evaporator with a minor leak, heater core, doors, actuators, etc.. To even get to those core hoses I might as well replace my leaking valve cover gasket on the passenger side to get a little more room to those core hoses. Fun...

I had to read your thread again because I thought your leak was on a core hose and that way you could for now just create a new hose loop from the 2 tubes on the timing chain cover and leave the heater core idle while plugging the hoses temporarily . But with a leak at the thermostat tube that's a real good idea your dad has to install a new hose where it's leaking and cut/splice it to the existing hose on the core in the middle where it's easy to get to.

Those heater hoses aren't very big ID and believe they're .62". That was off a spec off a replacement hose for my 04 4.7. And when I measured the OD with a micrometer yesterday it was 7/8" OD on the OE heater hoses. Of course you'd need a little bigger clamp with a coupling or fitting tube shoved in the hose.

If you're going to permanently or for now place your recirc door in one position believe I'd have it on recirculate. In other words have it open to the inside cabin and block the outside air. The main reason for saying this is you live in Vegas don't you and your wife is going to be driving your WJ? I don't know if I'd want 100+ degree outside Vegas air mixing with the AC air while trying to cool down the cabin. Fresh air is nice but it's a lot more efficient to have the half-cool cabin air entering the HVAC system rather than real hot air. Just my take before you hear it from "The Hammer". :-)

There's a little bit of good info on the recirc door positions in the below blendorstore tech tips at the end.

http://blendorstore.com/tech_tips

Pinning that door open or shut isn't much different with their kit than you tried with coat hangers. I think I even remember somebody installing a screw in one of the upper door corners to pin it to the housing away from the cabin. Good luck.

My leak is actually where the aluminum tube meets the rubber on the aft end of the tube. It is the upper hose with reference to the firewall, and I believe the lower hose (haven't looked at it in a few days) with regards to the thermostat/timing cover housing. I now know I have made the leak worse by fiddling with it, and have no choice but to loop it on the thermostat/timing cover end before our move. Since I took the new hose back, I need to figure out the ID sizes of the hoses where they connect to the front housing. Anyone know off the top of their head? I tried searching this, but nothing yet.

For today's project, I am going to go with your suggestion on leaving the HVAC locked on recirc, as most people I have talked with all agree. This will be my second time in there and I am going to try and make the tension of the coat hanger hold it against the fresh air intake. I admit using a screw would be better, but with my luck I would find a wire, or worse.

2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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post #14 of 18 Old 06-01-2020, 11:31 AM Thread Starter
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I am open to suggestions on the best, and easiest way to bypass the heater core. For me, working up front is easier, but I realize it may not be the best way. I will cut off and replace the oem heater hoses after our move, but for now, I need to loop it.

The HVAC is working! Getting in there a second time, I was able to see I left an ear of the coat hanger in the cage area. At my age, I'm unable to lay on my back under the dash, so I just missed it the first time. I want to say contorting a tensioned coat hanger in the flap area does securely hold the flap against the air intake, and to me easier than using screws or brackets. Also, there is no need to remove the glove box. Of course, not all wire coat hangers are created equal. It just so happens I had one which provided plenty of tension.

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post #15 of 18 Old 06-08-2020, 11:49 AM Thread Starter
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Sometimes we have to relearn a life's lesson. For me, it is don't take an older Jeep to a full service Jeep dealer for any reason no matter how simple the job.

Yes, pressed for time, I took it in to have the hoses replaced. The 252.00 for labor seemed reasonable, given the headache it was causing me. Of course the parts were slightly overpriced vs what you could get them on the street for, but at least they were Mopar.

As it goes, within the first hour of them having it, I received text messages and emails, of things that needed my immediate approval. It included everything from injector cleanings, brake pads, filters, and who knows what all. I thought I told them to just replace the heater hoses, but alright, I put up with it. A couple of hours later I get another call. The service rep tells me in a tone like someone just died, my Jeep won't hold a vacuum and there is an air sound coming from the heater core area (my thought is great, they broke the heater core.) I tell them to leave it alone, but not before he gets in the "it was like that when you brought it in" which further strengthened my belief they ruptured the core. Anyone who has been reading this thread knows I knew what was wrong with it beforehand, and that my heater core was fine. Later in the day, I get the final call to come and get it; the tech has test driven it, and at the moment, it is not overheating. The rep wanted to make sure I was worried about it. When I pick it up, it is running on the drive and I drove it home without any issues.

Next morning, I start it up and there is the waterfall sound which it has never had, and I was now convinced they had fractured the core. So, of course, now I'm pissed and decide to take a cooling off period before confronting them about the heater core. I keep driving it with the waterfall sound until day 3 on which the waterfall sound is surprisingly gone, and so far it hasn't returned.

So, I wonder, is it:

Lie number 1,,,they didn't know whether they had damaged the core, or not, and wanted to do some cya

or

Lie number 2,,,they left some air in the system so I would hear the waterfall sound and return it to them for the core repair

or

Number 3,,,they just suck

Regardless, I have relearned my lesson. There is one strange positive in that my AC is working better than it ever has, so I wonder if they removed the upper AC line for clearance, and then had to recharge it.

2001 WJ 4.7/80k "Old Bones"
1997 ZJ 4.0/154k Sold
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