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Rob_I

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During an oil change, I saw a very wet PTU and naturally freaked out.

Before:
20200923_133929.jpg


Brake cleaned the area, drove for a bit and saw a few drips of CLEAR fluid right at this bolt or maybe the seam. I could BARELY see it but it was slightly wet and shiny. I'm surprised it was so clear. Mind you I just changed my oil.

20200928_160557.jpg


Has anyone encountered a wet spot right there? I don't see anywhere else that is wet.

So my question is, why is a PTU bolt leaking perfectly clear fresh OIL colored fluid and not nasty PTU fluid? Could something be leaking engine oil higher up and dripping down? I just don't know this vehicle well enough mechanically and the more I dive into it, the more I am wishing serious torturous pain to the engineers who designed it. They obviously weren't mechanics. This has me totally stumped.
 


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Rob_I

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Slight update (deleted previous post):

I got under and took a very good long look. It "might" be coming from further up toward to top and dripping down but there is no absolutely room to see. I tried to smell the tiny amount of fluid and it might have been gear oil but it was very hard to tell as my sample size was tiny.

I'm not certain my PTU is original. There is a hand etched number on it and painted colors across the bolts and pieces almost like it was a reman. Is it possible that someone replaced my' 13 PTU with a newer generation and the vent is leaking? (per the service bulletin that says to hose clamp it)

The fomoco number on mine was Db53-7251-AK which according to one seller on ebay right now shows a vent model, so I went searching. Found the vent cap (completely hidden) and where it attaches to the PTU (another blind process). I could not feel anything wet up top so I'm not certain my vent is leaking.

Tomorrow's project is to do the "PTU filler upgrade" here https://www.explorerforum.com/forums/threads/ptu-oil-change-tons-of-pics-2016-explorer-sport.462691/ and drain my PTU, see if there is anything in it, and go from there. If she is empty, then I have a leak. At least now I know I can actually service it.
 




peterk9

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I think that the fact that there are painted colours on the bolts is a sign that it is the original unit. You will find such markings on other parts as well. I believe they do that so that it can be seen if the bolts and possibly the unit was ever removed/replaced.

Peter
 




Rob_I

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Like a tamper seal. That actually makes me more nervous. Wish it had been replaced seeing as how unreliable they seem to be.
 




DHG2496

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During an oil change, I saw a very wet PTU and naturally freaked out.

Before:
View attachment 321736

Brake cleaned the area, drove for a bit and saw a few drips of CLEAR fluid right at this bolt or maybe the seam. I could BARELY see it but it was slightly wet and shiny. I'm surprised it was so clear. Mind you I just changed my oil.

View attachment 321737

Has anyone encountered a wet spot right there? I don't see anywhere else that is wet.

So my question is, why is a PTU bolt leaking perfectly clear fresh OIL colored fluid and not nasty PTU fluid? Could something be leaking engine oil higher up and dripping down? I just don't know this vehicle well enough mechanically and the more I dive into it, the more I am wishing serious torturous pain to the engineers who designed it. They obviously weren't mechanics. This has me totally stumped.

I have a very similar looking PTU and drip there, I thought it was the axle seal (which might have been part of the problem) and found a crack in it and had it replaced (twice). However shortly after I still noticed a few drops on the ground( 1-2 drops on the ground following a drive vs 3-4 before). Some of it is hitting the exhaust and burning off. I put some paper under the car and it appears to be oil and not the trans or PTU fluid based on the color. I ripped my entire exhaust off to to try and get a better look and a likely candidate appears to to be the turbo return line, which looks rusty and wet. It is possible it's something above that, and if so would be more like a valve cover gasket if that is the case (not much else above the turbo that I can imagine leaking) and if you have a 3.7 you wouldn't have that line either.

I'll see if I can get some pics of my return line and post them back. One other thing that I did was put full synthetic in on the last oil change so I'm not sure if that is adding to the ability of the oil to seep out a little more easily. But the way this is so tightly packed in there its a huge pain to try and figure out where this is coming from. So I'm also eager to see if anyone else has ideas. I've done some searching and came up short.
 




Rob_I

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I used Mobil 1 for this last oil change. I don't know what was in it before. It was still the oil from the guy I bought the vehicle from. BUT when I had it looked over at for my state registration inspection, everything was perfect. No leaks. I mean, he could have done a thorough undercarriage wash before he gave it to me and it took a few months to leak meaningfully.

It's impossibly tight to get a good look at everything so I'm not discounting it's engine oil. The engine I can see is bone dry except for some seeping around the two sensors on the top left of the rear valve cover. The name escapes me, but leaking there is a known issue. If that is it, talk about a roundabout route for the oil to run downhill.

Regarding the PTU service, I only have 1/4" fuel hose on hand so I have to get some 5/16" to do the PTU drain and fill. I will report back when I do that. If I get around 0.5qts out and the color isn't clear, then it's not the PTU.
 




ecoboost_xsport

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PTU failures are a known issue with this platform...the fluid leaks out either past that hard plastic cover, which protects 2 seals or it pukes out the vent, which means you have bigger issues with the PTU. Neither are ideal scenarios. If anyone cares to know, I can probably explain it further, but a light Google search will supply you with plenty of evidence and information.

But I've done the PTU maintenance modification to mine and do frequent oil changes. Check the write up here:

Use Amsoil Sever Gear or the equivalent Redline product if at all possible.

I'm also attempting to do some experimental improvements to a PTU I purchased separately to see what can be done internally, but it is an ongoing project:

Lastly, if you're so inclined to go one step further, I do sell a drain plug set that facilities future maintenance, not only on the PTU, but RDU and transmission as well. $30 shipped, DM for more info. It does require some drilling, so it's understandable if that isn't an option. Just throwing it out there:
 




Rob_I

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The plastic cover is dry after a few hundred miles. The leak appears to be either at the bolt or higher up seeping down. I'll know more when I see the PTU fluid.

I've seen the kits however I have both a PTU and Trans drain plug. I do not need to suction on mine.
 




DHG2496

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PTU failures are a known issue with this platform...the fluid leaks out either past that hard plastic cover, which protects 2 seals or it pukes out the vent, which means you have bigger issues with the PTU. Neither are ideal scenarios. If anyone cares to know, I can probably explain it further, but a light Google search will supply you with plenty of evidence and information.

But I've done the PTU maintenance modification to mine and do frequent oil changes. Check the write up here:

Use Amsoil Sever Gear or the equivalent Redline product if at all possible.

I'm also attempting to do some experimental improvements to a PTU I purchased separately to see what can be done internally, but it is an ongoing project:

Lastly, if you're so inclined to go one step further, I do sell a drain plug set that facilities future maintenance, not only on the PTU, but RDU and transmission as well. $30 shipped, DM for more info. It does require some drilling, so it's understandable if that isn't an option. Just throwing it out there:
Thanks, I've been enjoying lurking and reading the PTU thread, amazing work! Any short answer on what causes it to puke fluid out the vent? any easy way to diagnose if that is happening and not some other leak further up the engine?
 




ecoboost_xsport

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Thanks, I've been enjoying lurking and reading the PTU thread, amazing work! Any short answer on what causes it to puke fluid out the vent? any easy way to diagnose if that is happening and not some other leak further up the engine?

Basically, Ford thought this would be lifetime fluid. Turns out it isn't, and even Ford recognized this by pushing out some fluid change intervals for the PIU fleets (I don't know specifics, apologies). Not to mention, there have been a few iterations of the PTU since it's inception. If you're going to get a new one, get the latest version (off a 2019 MY, it will fit fine). It's only 18oz of oil that sees a lot of abuse. Keep in mind, that PTU spins all the time. It is the RDU that engages and disengages for the AWD function. The PTU is essentially just a gearbox and is not "smart" in any way.

Now over time, or if the temperature of the gear oil exceeds a certain point (keep in mind these are right beside the rear catalyst as well), it can start to turn into a grease-like substance. Like black Crisco. This is where the downward spiral begins. That grease can no longer lubricate the bearings properly and specifically the idler gear bearing (notice where the cooler is located on the body of the PTU...right on the side where the idler gear bearing rests) starts to walk and/or losses its capability to do its job properly. This is where it would puke from the vent. Whatever remaining oil in there gets pushed out the vent as the grease is not allowing it to flow properly. Or if the grease is blocking the vent, may cause the case to over-pressurize and leak out one of the seals. Then it's a domino effect...things can be as mild as a bad bearing or as extreme as a cracked PTU housing. It's all different and at different intervals. It just depends on how bad the PTU gets abused...

Inherently, the gears are actually quite strong, and the bearings aren't necessarily weak. The real issue is the oil and the small amount that is in it. Keeping that oil cool with some sort of oil cooler (not just a simple plug-n-play for the PTU) in addition to the coolant housing that is currently has, adding more capacity with a sump setup or putting some cooling fins would be some design improvements I would think would be viable.

Sorry, hope I didn't ramble, LOL...
 




ecoboost_xsport

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The plastic cover is dry after a few hundred miles. The leak appears to be either at the bolt or higher up seeping down. I'll know more when I see the PTU fluid.

I've seen the kits however I have both a PTU and Trans drain plug. I do not need to suction on mine.

Yup, I have those OEM plugs as well, but still added the kits, just make it easier. Removing and re-installing NPT fittings over time can introduce leaks...it was an attempt at mitigating that. Definately not necessary though.
 




DHG2496

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Basically, Ford thought this would be lifetime fluid. Turns out it isn't, and even Ford recognized this by pushing out some fluid change intervals for the PIU fleets (I don't know specifics, apologies). Not to mention, there have been a few iterations of the PTU since it's inception. If you're going to get a new one, get the latest version (off a 2019 MY, it will fit fine). It's only 18oz of oil that sees a lot of abuse. Keep in mind, that PTU spins all the time. It is the RDU that engages and disengages for the AWD function. The PTU is essentially just a gearbox and is not "smart" in any way.

Now over time, or if the temperature of the gear oil exceeds a certain point (keep in mind these are right beside the rear catalyst as well), it can start to turn into a grease-like substance. Like black Crisco. This is where the downward spiral begins. That grease can no longer lubricate the bearings properly and specifically the idler gear bearing (notice where the cooler is located on the body of the PTU...right on the side where the idler gear bearing rests) starts to walk and/or losses its capability to do its job properly. This is where it would puke from the vent. Whatever remaining oil in there gets pushed out the vent as the grease is not allowing it to flow properly. Or if the grease is blocking the vent, may cause the case to over-pressurize and leak out one of the seals. Then it's a domino effect...things can be as mild as a bad bearing or as extreme as a cracked PTU housing. It's all different and at different intervals. It just depends on how bad the PTU gets abused...

Inherently, the gears are actually quite strong, and the bearings aren't necessarily weak. The real issue is the oil and the small amount that is in it. Keeping that oil cool with some sort of oil cooler (not just a simple plug-n-play for the PTU) in addition to the coolant housing that is currently has, adding more capacity with a sump setup or putting some cooling fins would be some design improvements I would think would be viable.

Sorry, hope I didn't ramble, LOL...
Appreciate the potential rambling as it helps me to continue learning on this topic I've been reading your other related threads and can't thank you enough for sharing on this topic..

Assuming it's already thickening, will the existing drain get it out or can I flush it with some new fluid and then do it again? I have no idea if the PTU has been serviced and have 105k miles now so probably a good idea to do it anyways, but with your experience on this I'm hoping I can be prepared to do it right this time and save it before it destroys anything. Thankfully it's seeing very few miles these days as I'm now a remote employee for the foreseeable future so it goes out for 5 miles or less a day.
 




DHG2496

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Last Question for the day (I can't promise that!) :)

@ecoboost_xsport - What Amsoil did you buy for the PTU? I didn't see it listed in your other thread and you;dn't read the bag well enough to see. If I'm doing this I want what the Pros are using! ;) and need to call around and see if anyone has it or can get it by the weekend. Looks like a project I need to tackle soon.
 




ecoboost_xsport

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Last Question for the day (I can't promise that!) :)

@ecoboost_xsport - What Amsoil did you buy for the PTU? I didn't see it listed in your other thread and you;dn't read the bag well enough to see. If I'm doing this I want what the Pros are using! ;) and need to call around and see if anyone has it or can get it by the weekend. Looks like a project I need to tackle soon.

Oh, man my bad! Looks like I should go add that to that write-up LOL.

It's Amsoil Severe Gear 75W-140.

I put Amsoil Severe Gear 80W-90 in the RDU

I've heard the Redline Shockproof variant is good as well.
 




Rob_I

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Yup, I have those OEM plugs as well, but still added the kits, just make it easier. Removing and re-installing NPT fittings over time can introduce leaks...it was an attempt at mitigating that. Definately not necessary though.

I do appreciate the kit and was reading through your PTU build thread. Can also appreciate that the fitting wasn't designed as a maintenance plug like an oil pan. I'm more leery of having a fitting extending below my vehicle with the potential of shearing off. I live in the woods of NH so running over ice and snow and debris will happen. If there was a replacement cap to the existing horizontal drain plug, that would be something...
 




ecoboost_xsport

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Appreciate the potential rambling as it helps me to continue learning on this topic I've been reading your other related threads and can't thank you enough for sharing on this topic..

Assuming it's already thickening, will the existing drain get it out or can I flush it with some new fluid and then do it again? I have no idea if the PTU has been serviced and have 105k miles now so probably a good idea to do it anyways, but with your experience on this I'm hoping I can be prepared to do it right this time and save it before it destroys anything. Thankfully it's seeing very few miles these days as I'm now a remote employee for the foreseeable future so it goes out for 5 miles or less a day.

TBH, i've thought about this long and hard myself. Trying to figure out ways to "clean/flush" that grease out. Luckily, mine has never gotten to that point so I hadn't done more than do thought experiments. I was tossing around the idea of flushing diesel through it at first, but not sure how that would react to the seals or how any residual diesel would effect the oil under normal operation, so maybe not a good idea. I then thought about buying a whole bunch of really cheap 75W-140 and heating it via a heat pump and flushing it that way. IDK, tbh...I haven't had to go there yet, LOL.
 




DHG2496

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TBH, i've thought about this long and hard myself. Trying to figure out ways to "clean/flush" that grease out. Luckily, mine has never gotten to that point so I hadn't done more than do thought experiments. I was tossing around the idea of flushing diesel through it at first, but not sure how that would react to the seals or how any residual diesel would effect the oil under normal operation, so maybe not a good idea. I then thought about buying a whole bunch of really cheap 75W-140 and heating it via a heat pump and flushing it that way. IDK, tbh...I haven't had to go there yet, LOL.
I was thinking about heat cycling it and do it a few times with cheap stuff. And do that once or twice then put the good stuff in.
 




Rob_I

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Ecoboost_xsport has been instrumental in helping me via PM. Big thanks to you fine sir!

Update:

I uneventfully drained my PTU fluid. Got 10 OZ out. Not particularly nasty and the drain plug was meh.

Made a curious discovery during my investigations. Apparently the PD who had the vehicle before me already did the vent filling mod but they used a barbed brass 90 on the top of the PTU with a spring clamp. Then the hose was routed up behind the throttle body and the vent cap on top. I added about a foot of 5/16" hose using a barbed fitting so I could fill it. The tight 90 makes putting a new longer hose on tricky so I'm opting just to extend it to fill. I'm on like tablespoon 2 of 18 OZ going in. This is gonna be a long night...
 

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Rob_I

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Still trying to fill. Maybe 1/3 if the way there.

But had an idea. Dual hoses. Try my best to get my spring clamp off the tight 90. Put on a short section of hose ending in a barbed brass Y or T. Then two sections of 2' hose going to the top, zip tied to something. One end is plugged, the other end has the factory vent. When needed, open both tube ends. Filling funnel in one, the other open for a breather.

Or I could shove a really tiny IV hose down the 5/16 vent hose for air. I don't have that on hand though.

Has to be a better way to fill it.
 


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ecoboost_xsport

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Yup, thats what I was saying....its slow because the air you're sdisplacing with the oil is coming out of the same hole your filling with...they are fighting each other. 2 lines would be ideal:

dR31uwglg6s6A?width=1024&height=1024&cropmode=none.jpg


Maybe not this large but you get the picture...
 




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