F150 transmission cooler lines- CHECK THEM!

[JoeDirt41]

Just a PSA. If you own an F150, particularly 2009-up, check your transmission cooler lines, NOW! It’s a known issue that they break, up under the front bumper where the quick connects are. I was driving around town the other day in my 2015 F150, and when I went to leave a store, the truck was shifting erratically, wouldn’t move, bucked and eventually wouldn’t move at all.

It was in the middle of a rainstorm so I couldn’t see the ground was wet and my truck is oil undercoated, so it wasn’t immediately apparent that there was a leak. But one of my cooler lines popped and drained the transmission completely, I imagine rather rapidly. I don’t know yet whether I caught it in time before any damage occurred to the transmission. I have to fix, or at least rig the line temporarily and test, but I won’t get to do that until at least tomorrow morning.

Anyways, check those cooler lines at the fittings. See if they are seeping or give them a tug and make sure they aren’t about to break. I would’ve replaced mine preemptively had I known this.

 

[92saturnsl2]

A lot like the early Mazda Tribute / Ford Escape brake lines (early 00's) that would spontaneously break at high-ish mileage/age. I'd rather a transmission line go south

 

[Drifter]

I had a line come undone. Drained 4plus qts before it wouldn't move . Fixed the line. Added fluid and the transmission was fine afterwards. Not an F150 though. Hopefully the same for you. And thanks for sharing your tip and experience.

 

[D60]

GM had this problem on the Allys through ~2010, but it was poor crimps. Most just leaked but our '08 blew apart at VERY low mileage with the same result as OP. I replaced with full-length hydraulic hose.

 

[benjamming]

Which transmission? 4R70W?

 

[zzyzzx]

Broken plastic?

 

[tcp71]

Which transmission? 4R70W?

6R80

 

[Hohn]

Broken plastic?

that's not plastic.

 

[Doc8404]

Initially, I was going to replace all those lines with straight up transmission hose and double clamps. It was the middle of winter, and I didn’t want to mess with it so I had the dealer replace those lines with OEM.
They still make me nervous.

 

[Doc8404]

that's not plastic.

Then what special material is it?

 

[zzyzzx]

replace all those lines with straight up transmission hose and double clamps.

That's what I would have done.

 

[Hohn]

Just a PSA. If you own an F150, particularly 2009-up, check your transmission cooler lines, NOW! It’s a known issue that they break, up under the front bumper where the quick connects are. I was driving around town the other day in my 2015 F150, and when I went to leave a store, the truck was shifting erratically, wouldn’t move, bucked and eventually wouldn’t move at all.

It was in the middle of a rainstorm so I couldn’t see the ground was wet and my truck is oil undercoated, so it wasn’t immediately apparent that there was a leak. But one of my cooler lines popped and drained the transmission completely, I imagine rather rapidly. I don’t know yet whether I caught it in time before any damage occurred to the transmission. I have to fix, or at least rig the line temporarily and test, but I won’t get to do that until at least tomorrow morning.
View attachment 284454
Anyways, check those cooler lines at the fittings. See if they are seeping or give them a tug and make sure they aren’t about to break. I would’ve replaced mine preemptively had I known this.

Engine plumbing is part of my profession. I can tell you the reason these lines are failing is twofold: the are under too much stress as-installed (owing to that flex hose bend being at or below the minimum bend radius) and the vibration level is too high.

You can get away with higher dynamic stresses if static stresses are low. And vice versa. But here you have high static stress (i.e. line is being muscled into position) and then vibration. This is causing a fatigue failure of the metal tube in the hose end. The ends are where the stress concentrates because it is the transition point between two different bending stiffnesses. Anytime you have a big change in stiffness, that's a stress concentration.

Your local hose shop can probably custom whip up something that will be better than factory if you know how to correct the design. An upgrade to some thicker wall Swagelok style tubing and then transitioning to hydraulic hose via push-lok is probably the most robust field repair you can do that doesn't replicate the original design flaw.


Do a sharp bend in hardline (this looks like 10mm line) and then transition to flex like this:

That should take some stress off the end and prevent recurrence.

Parker 801 and 836 are both useful push-lok hoses that will work for trans cooler applications. The 836 is preferable because it's rated to 150C vs 125C for the 801, but since those are industrial ratings, I'd consider the 801 to be sufficient even with only the 125C rating.

 

[Hohn]

Also, if you guys go inspect your trucks and find that the hoses haven't cracked yet, some prevention you can do is to try a spacer block that you can then zip tie them together and to the block:

This might still not prevent it, blocks like this usually just add static stress while subtracting dynamic, so if the block is radically altering the hose position, it could make it worse.

 

[JoeDirt41]

Engine plumbing is part of my profession. I can tell you the reason these lines are failing is twofold: the are under too much stress as-installed (owing to that flex hose bend being at or below the minimum bend radius) and the vibration level is too high.

You can get away with higher dynamic stresses if static stresses are low. And vice versa. But here you have high static stress (i.e. line is being muscled into position) and then vibration. This is causing a fatigue failure of the metal tube in the hose end. The ends are where the stress concentrates because it is the transition point between two different bending stiffnesses. Anytime you have a big change in stiffness, that's a stress concentration.

Your local hose shop can probably custom whip up something that will be better than factory if you know how to correct the design. An upgrade to some thicker wall Swagelok style tubing and then transitioning to hydraulic hose via push-lok is probably the most robust field repair you can do that doesn't replicate the original design flaw.


Do a sharp bend in hardline (this looks like 10mm line) and then transition to flex like this:
View attachment 284516

That should take some stress off the end and prevent recurrence.

Parker 801 and 836 are both useful push-lok hoses that will work for trans cooler applications. The 836 is preferable because it's rated to 150C vs 125C for the 801, but since those are industrial ratings, I'd consider the 801 to be sufficient even with only the 125C rating.

I assume you are a mechanical engineer? I find this very interesting, being a mechanical engineering student myself. For now I’m cutting the ends off and running high-pressure transmission hose with a clamp on either end. It’s inexpensive and I trust it more than the OEM design.

 

[Hohn]

I assume you are a mechanical engineer? I find this very interesting, being a mechanical engineering student myself. For now I’m cutting the ends off and running high-pressure transmission hose with a clamp on either end. It’s inexpensive and I trust it more than the OEM design.

View attachment 284537

Yes, professional ME. Good job on your repair. Just keep an eye on the clamps. You probably had little to no bead on the hardlines and worm clamps are famous for 1) destroying hose and 2) coming loose.

Replace those with spring clamps when it's convenient for you.

Better yet, you could adapt the hardline to flex hose with this kind of fitting:

McMaster has them in their YorLok line. This will transition from hardline tube to push-lock flex hose. This is MUCH more robust as a long term fix. The hardline end is a double compression fitting like a Swage-lok. Properly installed it will never leak.

Mcmaster has both the fitting and the Parker 801 hose that works so well with the push-lok barbs. Danfoss Socketless works well, also. I'm sure Gates and others have similar barb-compatible hoses, but I try to stay with Parker or Eaton (Danfoss now) for hoses.

 

[JoeDirt41]

Yes, professional ME. Good job on your repair. Just keep an eye on the clamps. You probably had little to no bead on the hardlines and worm clamps are famous for 1) destroying hose and 2) coming loose.

Replace those with spring clamps when it's convenient for you.

Better yet, you could adapt the hardline to flex hose with this kind of fitting:

View attachment 284543

McMaster has them in their YorLok line. This will transition from hardline tube to push-lock flex hose. This is MUCH more robust as a long term fix. The hardline end is a double compression fitting like a Swage-lok. Properly installed it will never leak.

Mcmaster has both the fitting and the Parker 801 hose that works so well with the push-lok barbs. Danfoss Socketless works well, also. I'm sure Gates and others have similar barb-compatible hoses, but I try to stay with Parker or Eaton (Danfoss now) for hoses.

Awesome! Sounds like you’re in the field I’m looking to get into once I graduate.

Honestly I initally just put that hose and the two clamps on as a temporary fix to make sure the transmission was not destroyed, just using stuff I had around. I was initially planning on replacing the whole line set with a new OEM one, but I don’t think I want to reinstall the same failure-prone fittings.

I agree, I’m not a fan of band clamps for the reasons you mentioned, I prefer spring (constant tension) clamps.

I’ve had very good luck with Parker-Hannifin stuff, I used all of their fittings and hoses when I built the snow plow setup on my tractor. I’d definitely use their products again.