Drivetrain clunking, smell, and slight lockup

[Dave JD]

Hi,
New to this forum, but a very experienced mechanic. This is my first Ford (almost all of my vehicles have been German), so I'm not familiar with them, and to date it has required little other than normal wear items.

Last evening my wife and I went out to dinner... and that's when I began to smell something bad. Smelled like a leaking propane tank, and was so strong we had to open the windows. Then I began to hear some drivetrain clunking, and you could feel it in the motion of the car... sort of hiccups. Then a sort of howl started when moving forward from a dead stop. We got home no trouble, but the noises escalated.

Today I took it out to try and learn more... short drive to the gas station and back. The smell has changed to that of burning gear oil, and the noises more frequent. It's most certainly coming from the front, and sounds louder on the driver's side. At the gas station I went to back up... put it in reverse, applied no gas. It rolled back about 2 feet and then locked. I was able to move forward, then back again. Drove home. On my way up my driveway, an alert came on saying AWD is off. Great. FWIW, each time I've changed engine oil, I've also removed the air cleaner housing so I can check the trans fluid, and it has never gone down.

This feels somewhat like a differential ring and pinion that is missing a tooth, or has a damaged spider gear... the noises and hiccups are more pronounced in a no-load situation, or decelerating. My guess is a significant trans or final drive issue (probably the later), which is quite disappointing for a vehicle with only 85k miles on it. I've owned over 60 vehicles in my life, and never had a drivetrain failure with so few miles. Plus, this is my wife's car, and she drives like a granny...

I'm betting this isn't a rare occurrence, and that someone out there has been through this with the Explorer. Any input, guidance, or BTDT appreciated.

Many thanks,
Dave

 

[peterk9]

Welcome to the Forum Dave.
From what you are describing, I'm thinking it is the PTU (Power Transfer Unit) that is going. There are several threads on that issue.

Peter

 

[thefranchise713]

All signs point to a blown PTU.

 

[Elfiero]

I think my opinion would be that the PTU died. Do a search and you will find a lot of info on the subject.

 

[Dave JD]

Thanks to you both. Can you give me any details on this component? Is it part of the trans, or something attached like a center diff? Or if you could point me to a thread. Searching seems clumsy, as I seem to get results from all forums, not just the Gen5 Explorers. Probably searching wrong...

 

[imp]

Thanks to you both. Can you give me any details on this component? Is it part of the trans, or something attached like a center diff? Or if you could point me to a thread. Searching seems clumsy, as I seem to get results from all forums, not just the Gen5 Explorers. Probably searching wrong...

@Dave JD

AFAIK, the >Gen 3 AWD uses a similar Transfer Case (APU) to what I'm familiar with; separate unit bolted onto the transmission rear output. It contains a Viscous Clutch which absorbs driveline speed differences between front and rear axles. If Gen 5 is normally front-wheel drive in the 2WD/4WD versions, I may not know WTH I'm talking about. At any rate, the viscous clutches can of course fail mechanically, thus making noise. imp

 

[Odrapnew]

I agree, PTU.

It is a separate component, but one thing I've learned is that if the PTU locks up, it could take out the transmission splines as well. I don't know if that's happened to any Explorers, but there have been a few instances on Mazda CX9's, which is a similar setup.

I wouldn't say this is common, but it has happened. Usually people experience leaking PTU and get it replaced before it locks up.

 

[peterk9]

Thanks to you both. Can you give me any details on this component? Is it part of the trans, or something attached like a center diff? Or if you could point me to a thread. Searching seems clumsy, as I seem to get results from all forums, not just the Gen5 Explorers. Probably searching wrong...

Perhaps this thread may help to some degree; How to: - PTU Oil Change (Tons of Pics) 2016 Explorer Sport

Peter

 

[613GT500]

Definitely the PTU.
While I was able to get mine towed to the dealership right away when it broke, that propane smell is very apparent.

 

[Dave JD]

Thanks for all the feedback... going to try and dig up a replacement procedure somewhere. Sounds like the various PTU symptoms are an exact match. Perhaps using a high quality synthetic gear oil (motul) might provide a better lifespan.

 

[613GT500]

Thanks for all the feedback... going to try and dig up a replacement procedure somewhere. Sounds like the various PTU symptoms are an exact match. Perhaps using a high quality synthetic gear oil (motul) might provide a better lifespan.

You will likely need to replace the entire PTU.

 

[blwnsmoke]

Thanks for all the feedback... going to try and dig up a replacement procedure somewhere. Sounds like the various PTU symptoms are an exact match. Perhaps using a high quality synthetic gear oil (motul) might provide a better lifespan.

Are you over the 5yr/60k drivetrain warranty?

If so, here is one of the cheapest places to get one.. they sell 10% over cost.

Transfer Case - Ford (DG1Z-7251-F) | Auto Nation Ford White Bear Lake

And here is what it looks like.

NEW OEM 2013+ Ford Power Take Off, PTO Differential - Transfer Case Unit AWD | eBay

 

[Dave JD]

Excellent... thanks. Since the dealer wants a silly price to replace, I'll be doing it on my own. Haven't wrenched on anything other than German for quite a few years, so should be interesting. Yes... I'm out of warranty, I've got about 80k on it. A very disappointing lifespan, however.... especially given that this vehicle only gets what I'd call light use. I'll go to the place "blwnsmoke" suggested for the PTU, but I am wondering if someone produces a better quality rebuild... something that might last forever like most transfer cases!!
Thanks again... all the info greatly appreciated.

 

[blwnsmoke]

The biggest problem is the "lifetime" fluid. Id do fluid changes every 25-30k and be done with it. It only holds about 1 quart of fluid which isnt a lot to last a lifetime.

 

[Tsuga]

For those that smelled the propane odour before the PTU went, how long did the smell last or is it constant?
My wife pointed this out last year, but recently I have been smelling it too. The smell comes and goes.
I wonder if this is related to the shudder I feel when
I am slowly accelerating from a speed of 90kph or 55mph.

 

[KayGee]

The biggest problem is the "lifetime" fluid. Id do fluid changes every 25-30k and be done with it. It only holds about 1 quart of fluid which isnt a lot to last a lifetime.

Just to clarify, it holds ~1 pint, not ~1 quart.

If it held a quart, it might actually have fewer problems.

 

[Dave JD]

The propane smell in ours went on for about a year... getting worse along the way. We'd really notice it when we took camping trips. Usually longer drives to our destination - minimum of 200 miles - then slow driving through the woods etc, to our final spot. You'd really notice it when driving slow on the trails after the longer drive. Several times we inspected our camping gear looking for a leaking propane canister.... ha!

I did end up replacing my own. The smell may have been exaggerated due to the fact that I discovered the vent tube wasn't still attached. Mine is a western car, meaning little underbody corrosion to make the job more difficult. The whole project took about 5 1/2 hours, which I thought was amusing given the estimate from the dealer and that it was my first one. There's really nothing difficult about it for someone with mechanical experience. Not what I would call a well engineered component, and it is surrounded by heat producing engine components, including the rear turbo. Don't ever lose that duct from the front bumper cover that blows air in that area.... I think it's the only thing that gives the PTU a chance.