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1994 K3500 extended cab dually

There’s a good hydraulics shop near me that I’ve worked with before - they made all the hoses for the skid steer. I know they could make whatever I wanted. It’s tempting to take the braided hoses I made and have them duplicate them in good hydraulic hose with crimped fittings, but I know that won’t be cheap so I’ll probably run some combination of hydraulic and ni-copp to keep costs down.
 
Got the hoses removed. Here’s the one that failed. It’s the outlet hose on the trans.

627F68E1-72F9-4E79-B88A-F04968E13ECB.jpeg

You can see it was a hose failure, however it looked like it had some help - I didn’t take a pic of it before I removed it, but the fitting was pointing almost vertical, which was putting stress on the hose at that point. I found the initial install pic and it wasn’t in that position then.

F230D35B-396B-4BDD-9C7D-43258B302167.jpeg

And the fitting in the trans was a little loose. Did I not have the fitting 100% tight? That doesn’t seem right because it would have tightened more when I attached the hose end to it. Still, it doesn’t make sense it would have rotated further in that direction because that’s clockwise rotation. Odd. So without that I suppose the hose would have normally survived, but I don’t want to risk it. Still working on future plans that will be more durable first and more roadside serviceable than these hoses/fittings second.
 
I just removed the fitting from the trans. The o-ring is misshapen. So I guess the o-ring gave up and allowed the fitting to rotate beyond initial installation? Still doesn’t make a ton of sense, but that’s all I can put together with the evidence. B7265154-FB04-44BC-8225-A92E438D26ED.jpeg
 
MrMarty51 said:
Is that fitting grooved for an o ring ? Usually if they are not, it will squish the o ring out from between the two surfaces.
Click to expand...

You know, that’s a good question, and I can’t answer it at the moment because I just got out of the shower to wash the ATF bath off of me. I think there’s a chamfer in the trans case that the o-ring sits in. And if that’s the case, it looks like the o-ring on this fitting was too large and instead of the metal surfaces contacting each other when fully tightened, it squished the o-ring in between them. So when I torqued the fitting into place, it registered correct when it squished the o-ring hard enough, but then with some heat cycles the o-ring started to give some. I’ll dig out the factory fitting and compare the two, but this is starting to make sense.
 
ak diesel driver said:
That's the rear fitting right? It needs to be exactly the same as the factory fitting as it holds internal parts in place. I'll see if I can find more info as my memory seems to be off anymore.
Click to expand...
Nope, that’s the front fitting. The rear fitting I used does have the extended part that engages the center support. Thanks for thinking of that though.

These are what I used to be able to use AN fittings.

ICT Billet 4L80E Transmission... https://www.amazon.com/dp/B01N16EZSL?ref=ppx_pop_mob_ap_share
 
FellowTraveler said:
I use AN fittings & hose extensively aside the heat range of the components fire sleeves are required in areas prone to excessive heat.
Click to expand...
As I’ve been researching options, I’ve been seeing a lot of people that are running AN fittings and braided hose for trans cooler lines. I think I made a mistake running the hose with the nylon outer layer rather than stainless. I also believe there was an issue with the fitment of o-ring on the adapter fitting that caused it, and the hose end, to rotate which started the problem. It’s tempting to try again with stainless braided hose, but I still have a bitter taste in my mouth at the moment.
 
A little more info. Here’s the stock line fitting next to the ICT adapter fitting. Note the lack of an o-ring on the factory fitting.

53B1DDBC-131C-43F8-8210-B3AC4F714D8B.jpeg

You can see here that there’s thread sealant on the threads of the AC Delco part.


And here are some pics of the port in the trans. There isn’t a smooth chamfer at the edge of the hole, so not only was there not a lot of extra clearance for the o-ring, but there are some threads that chewed up the edges of it as well.

A53226A2-A817-412E-B496-4D729F6AFABC.jpeg0160FF7A-72C1-4F73-A095-72C4548F693E.jpegEC777425-CA28-4338-92C1-70FD1D069342.jpeg
 
n8in8or said:
As I’ve been researching options, I’ve been seeing a lot of people that are running AN fittings and braided hose for trans cooler lines. I think I made a mistake running the hose with the nylon outer layer rather than stainless. I also believe there was an issue with the fitment of o-ring on the adapter fitting that caused it, and the hose end, to rotate which started the problem. It’s tempting to try again with stainless braided hose, but I still have a bitter taste in my mouth at the moment.
Click to expand...
Fittings to test that AN hose and fitting assemblies are holding pressure and not leaking are dirt cheap...
 
I have my repair planned and materials ordered. I am going to run the new lines 100% with nickel-copper 3/8" tubing. I am replacing all existing fittings with steel hydraulic fittings in a 37 degree JIC configuration (same angle as AN) with 2 exceptions. These exceptions are: 1) the adapter fitting in the transmission. I found a fitting made by Earl's that adapts from the trans outlet to 6AN like the ICT fitting did. However, this fitting is steel and has a washer for sealing against the case and not an o-ring. 2) I'm not going to replace the fittings between the transmission inlet and the fluid thermostat because that's all rigid and supported by a bracket. I should be able to get started on the repair on Friday. It hurt reordering the Schaeffer's All Trans Supreme......there's an expensive puddle in southern Michigan right now......just one more expense to add to the list for this debacle.
 
n8in8or said:
Got the hoses removed. Here’s the one that failed. It’s the outlet hose on the trans.

View attachment 65630

You can see it was a hose failure, however it looked like it had some help - I didn’t take a pic of it before I removed it, but the fitting was pointing almost vertical, which was putting stress on the hose at that point. I found the initial install pic and it wasn’t in that position then.

View attachment 65631

And the fitting in the trans was a little loose. Did I not have the fitting 100% tight? That doesn’t seem right because it would have tightened more when I attached the hose end to it. Still, it doesn’t make sense it would have rotated further in that direction because that’s clockwise rotation. Odd. So without that I suppose the hose would have normally survived, but I don’t want to risk it. Still working on future plans that will be more durable first and more roadside serviceable than these hoses/fittings second.
Click to expand...
One of two (2) things caused that failure 1st improper fitting to hose 2nd a defective hose core...a defective hose core would be soft as a pile of s__t.
What core did the hose have that you used teflon or rubber?
 
FellowTraveler said:
One of two (2) things caused that failure 1st improper fitting to hose 2nd a defective hose core...a defective hose core would be soft as a pile of s__t.
What core did the hose have that you used teflon or rubber?
Click to expand...
I think there was a 2-part failure mode: 1. the adapter fitting in the trans case wasn't proper with the o-ring sealing design and that allowed the fitting to rotate, which created stress on the hose below where the hose entered the 90 degree fitting. 2. the braided nylon exterior hose wasn't strong enough to deal with that stress so the interior metal fibers of the hose failed because there wasn't enough exterior strength in the body of the hose. I think a stainless steel braided hose probably would have survived......or at least survived a lot longer, but the braided nylon just didn't have much to offer in that condition. Now to your point, it did feel really soft when I reached under there to try to find where the source of the ATF leak was, but I don't know what to compare it to either.

This is the hose I used. It's synthetic rubber.

Vibrant Performance 11976 Vibrant Performance Braided Flexible Race Hoses | Summit Racing

What hose and fittings have you used in an auto trans application?
 
Great job! The transition from wrinkled sheet to this grey overhead console is amazing. You have motivated me to bring these changes to my camper as well.
 
n8in8or said:
I think there was a 2-part failure mode: 1. the adapter fitting in the trans case wasn't proper with the o-ring sealing design and that allowed the fitting to rotate, which created stress on the hose below where the hose entered the 90 degree fitting. 2. the braided nylon exterior hose wasn't strong enough to deal with that stress so the interior metal fibers of the hose failed because there wasn't enough exterior strength in the body of the hose. I think a stainless steel braided hose probably would have survived......or at least survived a lot longer, but the braided nylon just didn't have much to offer in that condition. Now to your point, it did feel really soft when I reached under there to try to find where the source of the ATF leak was, but I don't know what to compare it to either.

This is the hose I used. It's synthetic rubber.

Vibrant Performance 11976 Vibrant Performance Braided Flexible Race Hoses | Summit Racing

What hose and fittings have you used in an auto trans application?
Click to expand...
HIGH TEMP PTFE AKA:TEFLON core hose and the core should be rigid, not soft, the soft crap is CHICOM. Each hose has a max radius built into it and the sellers should have "all" the specs and know if the hose is conductive or not.
The hose is generally external SS braid w/PTFE core and optioned for external braid in various materials...
Fittings are for PTFE ONLY swivel, reusable, forged and hydro formed in radius, once fitting is installed to hose a pressure test will verify if it will hold...takes all the guess work out of using them.
 
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