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Guest Message by DevFuse

The official Ford authorized Ford Edge Registry is now live. More here!


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PTU discontinued by Ford


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86 replies to this topic

#81 OFFLINE   macbwt

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Posted 10 July 2017 - 04:56 AM

Ahhh, so "that's" how he went 200k and never had a problem. lol

I did my research.  I aim for longevity at low cost.


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#82 OFFLINE   akirby

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Posted 10 July 2017 - 07:33 AM

The last theory I heard was that individual parts tolerances were adding up causing too much friction and heat.   That would certainly explain why it's hit or miss.  Maybe that's causing the initial seal failure.


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#83 OFFLINE   IWRBB

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Posted 10 July 2017 - 08:37 AM

I did my research.  I aim for longevity at low cost.

Same here- I bought FWD specifically due to the PTU issue on AWDs.



#84 OFFLINE   beston38st

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Posted 10 July 2017 - 09:56 AM

Just another data point.  My 08 AWD Limited has 210K on it.  I had to replace a PTU seal at 90K (which I caught right away) but never had any other issues.  Perhaps it is luck of the draw and perhaps I'm one of the "lucky" ones but mine is still going strong.  



#85 OFFLINE   JohnCT

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Posted 10 July 2017 - 11:38 AM

Excellent argument, but how do you explain that the majority of cars over 100k and don't have a PTU problem?

 


 

 

 

We know how  many Ford made, but do we really know how many fail?   When the Jeep dealer asked about our trade, I told him it was an Edge and had a problem.  *He* asked if it was the PTU.  Seems they had a bunch of Explorers and Flex' they took on trade that they had to replace them in.  I laughed, told him yes, and I had the new PTU in a box in the back and he still didn't want it despite it being a loaded Limited pearl white with vista roof and nav.  The word is out.

 

When I brought one of my Escapes in for a trans rebuild a couple of years ago, I asked the owner (independent shop) how the Edge trans were, and he told me the PTUs were far more trouble.  It was then that I suspected the noise and vibration I was hearing was not the rear wheel bearing.

 

I have to believe that if it was just the location next to the cat, this would be common to all AWD & I would think we would be seeing a much larger percentage of failures. I have to believe Ford engineer's did their due diligence and knew full well the area thet were installing it into. Heat shield?

 

 

 

Maybe.  I don't pretend to know for sure, but there's definitely a chicken or the egg thing going on. Somebody here who is reported to be "in the know" said the problem could be a one time overheat of the PTU fluid, so regular maintenance would not prevent this (I had suggested a long term coking of the fluid).

 

It could very well be a seal failure leading to loss of fluid leading to overheating of the remaining fluid due to less of it and more friction with less lubrication.  The other possibility is that the box just gets too damned hot causing the seal to fail from the scorching heat, or failing due to loss of lubrication by the scorched fluid.  Again, chicken or the egg.

 

The other thing that bothers me is that the PTU is mostly free wheeling; the majority of engine torque is transferred to the front wheels through the intermediate shaft, not the PTU.  Also, there are no clutches in the PTU. Is it really possible that this box generates that much heat without handling that much torque just from friction losses?  Perhaps. Again, I'm not a mechanical engineer.

 

Back when I planned to keep the Edge, I was going to mount a thermocouple on the far side off the PTU (away from the cat) and measure the temperature of the PTU during stop and go, highway driving, and pulling long hills (which we live among around here).

 

If the PTU showed steady temperatures well within the capability of the lube, it would make sense that a leak might be the trigger.  But if the PTU showed wildly differing temps, then my plan was to fabricate a heat shield and air deflector to keep the cat's heat off the PTU and redirect airflow under the car over the PTU.

 

I took a far easier path and gave the car to my sister.  Other than the Nav acting up right now, she absolutely loves this car.

 

John



#86 OFFLINE   enigma-2

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Posted 10 July 2017 - 12:52 PM

Shame you didn't get around to monitoring the temp in the PTU. That would have been interesting to see what's really going on. I have the factory tow option and she's pulled a boat and been towed to FL more than once. It would seem that if anything, towing would put a (heat) load on it more than anything else. I wonder.... if the units failing had aftermarket hitches and exceeded to towing limit recommendations? There has to be some variable that affects some PTU but not otheres. Cant believe it's the heat from the cat as Ford would have certainly considered this (and under all circumstances).

If we assume that a single overtemp cab cause the cooking of the lubricant, I would expect to see additional damage as well. Assuming a standard cat is running between 1200° to 1600° and then either through a vacuum leak causing a lean condition or a plug misfiring causing a rich condition, the cat could running as high a 2000°F. At those temperatures, even for a few minutes, I would expect the cat to begin to fail, the aluminum oxide honeycomb could melt causing a partial or complete blockage, or the platinum / palladium coating on the honeycomb may start to melt and reduce its effect its ability to process thw exhaust gas. Either way, a malfunctioning catalytic converter should start throwing codes. Ford should have taken this possibilities into consideration during the design phase.

Anyway, I figure that if it goes out I'll just replace it. It already has over 100k on it, so if I have to throw in $1800 for a new one, still worth it if the rest of the car is still cherry. (And it is). $1800 every 100k is not that big a deal considering what car payments would run for a new one.

Glad your sister has a great car to drive. That was really nice of you to fix it and give it to her. Consider this a pat on the back. :rating:
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#87 OFFLINE   macbwt

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Posted Today, 09:04 AM

One thing not really mentioned is the combination of heat, friction and lastly the small amount of lubrication fluid. 12oz.  I believe the Ford engineers are asking a lot from a small amount of lubrication fluid.  i.e.   32oz of fluid would withstand heat much better than 12 oz.  

 

My local police garage has figured out the PTU issue and stopped failures of the PTU in the Police cars.  They change the fluid every 10K miles and the PTU failures came to a screeching halt.  Mechanic I talked to said Ford even sent a rep to the garage to find out what they were doing to stop the failures.  Simple consistent and frequent fluid changes.   They even refill the PTU through the drain plug by using a syringe.






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