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PTU Problems

Discussion in 'Stock 2011 - 2019 Ford Explorer Discussion' started by GeoMimi89, December 9, 2012.

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  1. VCFP153

    VCFP153 Active Member

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    My experience with bearings has been all over the place. Some barely made it past 60K (granted, on a car that was by then nearly 25 years old), some reached around 125K.
     
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  3. royski

    royski New Member

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    Got my explorer back from the transmission shop. Turned out, the PTU was overheating and spiting out the vent hole. The way it dripped, it looked like it was leaking from the seal. I plan to replace the fluid every 30k miles or so just to be safe from now on.
     
  4. ExPlat

    ExPlat Elite Explorer

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    Glad to hear it was a simple fix, regular fluid changes ought to help too. Your transmission shop sounds like a good one, congrats!
     
  5. Keith N

    Keith N Elite Explorer

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    @royski
    I’m confused. If it was overheating what was the fix? Did the oil turn to sludge so they flushed it? Was it low and they just added oil? Curious how they fixed it. Thanks
     
  6. aypanthony

    aypanthony Member

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    Once the fluid goes bad, it turns to sludge and overheats easily. It tends to start spitting out the vent hole once it starts going bad. A lot of people don't notice this happening before the PTU destroys itself. Luckily, royski might have caught it early enough that the PTU wasn't damaged before he changed out the fluid.
     
  7. ExPlat

    ExPlat Elite Explorer

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    I'd tend to agree with the idea that 'a lot of people don't notice this'. I have wrenched on cars all my long life, not so much now but understand the principles and have known about this PTU issue before I bought my Explorer, I had a Ford Flex years ago. I was aware and notice things like drops of oil/fluid under the car, odd smells and different driving characteristics. None of that was present before my PTU failed. So, yeah, a lot of people are not prepared for their PTU to spew gear oil out the vent hole and destroy the gears, unless they crawl under the car and do hands on inspections. Even then, just a month before my PTU 'vented', I had the Dealer perform an oil change that included a Ford 30,000 mile multi-point inspection, they didn't notice anything unusual either (or didn't look).
     
  8. blwnsmoke

    blwnsmoke Staff Member Moderator Elite Explorer

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    I'm going to go with "didn't look".
     
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  9. aypanthony

    aypanthony Member

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    Just to expand on your thoughts and my experience, we purchased our 2013 with 67k miles on the odo. Pretty early after we owned it, I would smell the telltale propane like smell. I even think I saw a black drip of oil on the garage floor. After researching the issue, I was pumped out the PTU fluid and replaced with Royal Purple. The fluid was black and smelled burnt. It wasn't all slugged, like I have seen on other posts. Ever since that change, I have not smelled anything unusual and there have been no random oil dips. I think if I would have waited any longer, my PTU would have imploded, especially considering that I tow a travel trailer during summer trips. Going forward I am going to change out the PTU fluid every 20-30k.
     
  10. Keith N

    Keith N Elite Explorer

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  11. aypanthony

    aypanthony Member

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    Around 87k now. I'll probably change the PTU fluid again soon.
     
  12. 613GT500

    613GT500 Well-Known Member

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    Considering my PTU failed at less than 30k miles without any leaks or smell, it is a hit or miss to catch it.
     
  13. KayGee

    KayGee Well-Known Member

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    I may have missed it, but for those with PTUs that failed @<30K miles, was there an actual determined cause of failure?

    Was it low fill from factory or something else?

    The most common points of failure in differentials and transfer cases are due to lubrication (lack of causing excessive wear) or too much power applied while tires are stuck (jackrabbit acceleration, uneven traction causing tires to break loose and grab repeatedly, vehicle stuck against an obstacle/off roading, etc...).
     
  14. ExPlat

    ExPlat Elite Explorer

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    My Work Order is shown in Post #501, says 'found fluid burned up'.
     
  15. 613GT500

    613GT500 Well-Known Member

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    Was driving normally in stop and go traffic to work and heard a loud bang, followed by the propane odor and that was it.
    I pulled over into a strip mall parking lot and called a tow truck right away.
    Dealer didn't even bother to take the PTU apart as the oil was already leaking out of the vent and that was enough for them to make the decision to replace it.
     
  16. KayGee

    KayGee Well-Known Member

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    Well, I think we all know that fluid doesn't just burn up in such a short time. I wonder if your ptu was underfilled or maybe had the wrong fluid put in. Assuming you didn't drive it like a crazy person. ;-)

    I didn't think I saw a cause of failure. Very hard to say what the real cause of failure is, but, I have to wonder if a proper pre-delivery check that ensured the ptu was filled to capacity with the proper fluid would have led to different results or if yours was just defective and just gave up the ghost when it did...
     
  17. Keith N

    Keith N Elite Explorer

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    Kaygee - there are some theories floating around for the early failures. The most likely to me is the gear mesh is on tight side of manf. tolerences. and generates extra heat. The ptu is located next to rear cat, so it gets hot already, regardless of whats happening inside the unit. This added "gear induced" heat puts the ptu over some binary failure mode for the oil. (other forums have mentioned 340 degrees). The oil is damaged and turns to sludge and stops lubricating. It may spill out of vent also, some catch it, some don't. Personally, if this is true, its best to let it fail early (under warranty) and roll dice with a new unit that hopefully has looser gear mesh.

    I work in the auto industry and we lubricate 30,000 parts a day. The equipment that dispenses grease and oil is so accurate, I cannot see many failures due to underfill. Not saying it isn't possible, just does not seem likely to me.

    From very limited data points, it does seem that if you get a good ptu, it can last up to 150k with original oil and you don't have a thermal event (like driving in sand, towing up a mountain where cat is generating a ton of heat). For those that change the oil, it should be more I would think. I know I have 100k on my 11 now. I changed it at 60k and just now, at 100k. Oil was normal at both changes IMHO.
     
  18. ExPlat

    ExPlat Elite Explorer

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    Yep, I played it smart, I let it fail early. My Dealer wouldn't change the fluid so I let them change the PTU. :thumbsup: When I had my 2012 Flex this was a big forum conversation way back then and it's still going on. Trouble is, it's such a nice vehicle in so many ways we put up with it.
    We'll never know the specific reason for the failure of the majority of these PTU's but one thing I can rule out is the 'driving like crazy', not guilty. Wait, you didn't say that, you said 'drive it like a crazy person', hmmm, strictly speaking that may apply. :laugh:
     
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  19. KayGee

    KayGee Well-Known Member

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    I've worked in auto for over 20 years. I've seen and heard a lot of crazy shit. Even with the best laid plans and ISO/TS/audit trails, shit still happens.

    As far as gear mesh, I would consider that a defect if it wasn't correct. If there is a spec and the nominal is fine, but a part at min/max is subject to early and explosive failure, than there is a problem with the spec. Typically, parts of an assembly should be gauged/matched to ensure all component parts combine to a workable and in spec assembly. For example, with a bearing, your major component parts are an outer race, inner race, and balls - all three major components can't be at their min or max spec, so you may have an outer race at max, an inner race at min, and that is combined with balls at nominal to make an in spec assembly. Typically, testing is done on assemblies at nominal, min and max spec to ensure any and all parts coming off the line are good. If the component parts of the ptus aren't being gauged/matched or the specs aren't ideal, that would explain the total randomness of some being okay and others being ticking time bombs. As I said before, something like this, coupled with the known issues and revisions and the low fluid fill, there are a lot of things conspiring against it.

    A far as fluid fill quantity, I can't say why some are underfilled. For all I know, maybe 12 oz was the spec at one point and it was changed, but somehow ptus were still filled with 12 oz after the change was made?

    As far as other heat sources, like overloading from driving in sand (getting stuck), that would seem to indicate the ptu isn't sized for the application, likely due to packaging/cost concerns. As far as the excess heat from the cat, that too, would seem to be an issue with the fluid fill not being adequate to shed all the direct and indirect heat making it's way to the unit - again, a spec issue, likely due to packaging concerns. The only way I can see to combat these issues is to be cautious with situations like these and check/change the fluid even more frequently. Unfortunately, not all ptus have the drain plug and are as easy to service as changing engine oil.
     
  20. Lexingtonian

    Lexingtonian Active Member

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    Just wanted to toss out there for anyone doing this for the first time. Gear oil smells burnt right out of the bottle, it's very strong and much different than motor oil. It's just the way it smells. Worn gear oil will however have a stronger odor but want to share that smell is normal.

    20,000 mile changes may be too aggressive but of course to each his own. See my multiple oil analysis reports here which pleads the case for up to a 45,000 mile interval (I'm doing no towing but do I get on the throttle a lot and I'm tuned up to roughly 450HP):

    Explorer PTU - Oil Analysis

    Looks like the most important thing one could do is drive it 5,000-10,000 miles, drain it to get the metals out, then go to a 30-45K change regimen based on driving/towing habits and your preference.
     
  21. KayGee

    KayGee Well-Known Member

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    Your oil analysis is specific to your PTU. I wouldn't rely on it to determine my change interval and no one else should either - too many variables.

    If we are to believe that ptu specs are all over the map, then a PTU that is at a different spec from yours (nominal vs min vs max) may cause the fluid to degrade at a different rate. An underfilled ptu may suffer from fluid degradation faster than a properly filled unit. Driving style and other factors also play a role. That's why OCIs can vary substantially from one vehicle to another depending on how many start/stop cycles, length of each cycle, and so on.

    I choose to change my vehicle fluids on a schedule that makes sense for me and if that means I change them at a shorter interval when it's convenient rather than waiting to hit a magic time/mileage, so be it. DIY fluid change costs are pretty minimal. If one wants to change fluids earlier or later then a published interval, or rely on an oil analysis where someone else suggests a change interval for their specific vehicle, then more power to them.
     

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