PTU failure

[Kevin81]

So, I did the tune. Flushed out the ptu one more time, now with a drain plug. And refilled with lightweight shock proof.

And decided to hold the break, and launch from 2,000 rpms.

And then smelled the dreaded gear oil in the cabin symptom. Went away shortly after, under more normal driving.

My question is this...when the PTU fails...what actually happens? And explosion of oil and metal? A grinding crunching of gears followed by no forward motion?

 

[Ecoboost_xsport]

From the way it was explained to me, after the oil has exceeded its life (either by length of time or excessive heat), it begins to form into a crisco-like grease. At that point, it is no longer lubricating properly. I've heard the first thing to go is the bearing for the idler gear inside the PTU. Once that bearing fails, all the tolerances go out of spec and things descend into the depths of **** pretty rapidly after that. If you notice on the newer PTUs with the cooler, its right where the idler gear bearing sits inside the case.

But that smell emanates from the vent and wafts into the cabin if it starts burning. However, you just did a change. How did the old oil look? Were you able to stick something inside there to see if you get a grease-like version of the oil to manifest? Were you able to drain a full 18oz out? I'm wondering if that burning smell right after the change is some that has pushed out the vent.

 

[Kevin81]

From the way it was explained to me, after the oil has exceeded its life (either by length of time or excessive heat), it begins to form into a crisco-like grease. At that point, it is no longer lubricating properly. I've heard the first thing to go is the bearing for the idler gear inside the PTU. Once that bearing fails, all the tolerances go out of spec and things descend into the depths of **** pretty rapidly after that. If you notice on the newer PTUs with the cooler, its right where the idler gear gearing sits inside the case.

But that smell emanates from the vent and wafts into the cabin if it starts burning. However, you just did a change. How did the old oil look? Were you able to stick something inside there to see if you get a grease-like version of the oil to manifest? Were you able to drain a full 18oz out? I'm wondering if that burning smell right after the change is some that has pushed out the vent.

This was my second change in 3,000 miles. Unsure how much came out. Way more than the first time. Put a little over half a bottle in.

How will I know when my PTU has "failed".

 

[SM105K]

This was my second change in 3,000 miles. Unsure how much came out. Way more than the first time. Put a little over half a bottle in.

How will I know when my PTU has "failed".

The case usually cracks and there is PTU fluid everywhere.

 

[SM105K]

If you smell gear oil in the cabin after you swapped fluid then it is residuals burning off.

Did happen to make sure the vent on top was clear as well?

 

[mrhighcaliber]

"And explosion of oil and metal? A grinding crunching of gears followed by no forward motion?"

Couldn't have outlined the catastrophic failure mode of a ptu better myself. This is exactly what is to be expected.

This failure mode is usually only expected if the ptu has never been serviced.

You've got fresh **** in yours, so a failure mode like this is unlikely for you, unless you break a gear tooth and it jams.

Sent from my PH-1 using Tapatalk

 

[Kevin81]

The case usually cracks and there is PTU fluid everywhere.

Ok. Well...



I hope that doesn't happen. At least, not till next year.

 

[Kevin81]

If you smell gear oil in the cabin after you swapped fluid then it is residuals burning off.

Did happen to make sure the vent on top was clear as well?

No. Suppose I should have...

 

[jman1200]

How will I know when my PTU has "failed".

I read a bunch of PTU threads looking for this answer and did not find anything conclusive besides an obvious catastrophic failure leading to a broken case. The smell could be an indicator when you know the fluid has never been touched but otherwise, I'd expect some grinding noise way before the BUM !

 

[FiveLeeter918]

ya'll are making me knock on some hard wood sitting at 86k miles and having never serviced the PTU with a couple hundred hard launches and a couple dozen track outings...

Sad thing is I bought Redline fluid 2 years ago when I first got the car, but the drain plug is stripped and been too lazy to chase it.

 

[SM105K]

Usually you do get gear whine from the PTU before it fails too. If you hear that, you are done.

 

[Kevin81]

No gear wine.

Just a bit of crunching/grinding/knocking sound/feel when the wheels are turned hard either way, and a little gas is applied. But I believe that to be traction control.



SHIT!!!!

I forgot to ask if the traction control could be disabled in the tune...ah well. I'll eventually get a revision. Ill eventually figure out a way to run e30.

 

[High on Ethanol]

traction control can be......adjusted to suit with a tune. I see no purpose in it really though.

 

[krewat]

I've had three PP SHO's, a 2013, a 2016, and now my 2018 which because of COVID is going to be the lowest-mileage 15K/year lease I've ever owned... I was already working from home a lot, and now, it still has like 7200 miles on it, and I got about a year and a half left on the 39 month lease. I guess the 18K buyout at the end will make a lot of sense...

ANYWAY... my 2013 after about 36K miles started to get a whine in it - and I thought it was the fuel pump. It had already been recalled for the FPM, but I still figured that maybe the thing got loud. It sort of went "in and out" as I let off or touched the go-pedal, but to some degree, it sounded like it was coming from the front, not the rear.

Sounded like a bearing whine. Kinda like a front pinion bearing on a rear-wheel-drive differential going south. If I drove around with the radio on, it was almost unoticable.

By the time I got down to the end of the lease, and had to extend it another 2 months as they tried to find me a new 2016 (no Sync 2 for me this time), I was convinced it was the PTU.

Now, I beat the EVER LOVIN' CRAP out of that car. Untuned, but still, scared the bejeezus out of myself quite a few times. Reenacted the famous "slide to the left at high speed" scene from that race car driver in one of the original SHO commercials for the 2013 I think.

My 2016 never made a peep. The 2018 doesn't either. Although, I have the fluid for the PTU to change, just haven't gotten under there yet

 

[krewat]

No gear wine.

Just a bit of crunching/grinding/knocking sound/feel when the wheels are turned hard either way, and a little gas is applied. But I believe that to be traction control.

Sounds like a front CV joint, or possibly a wheel bearing.

 

[Kevin81]

traction control can be......adjusted to suit with a tune. I see no purpose in it really though.

traction control can be......adjusted to suit with a tune. I see no purpose in it really though.

I want to be able to turn off traction control to test if my noise/vibration I get at sharp turns is traction control or something else.

 

[Kevin81]

Sounds like a front CV joint, or possibly a wheel bearing.

It only does it under load. If I already have momentum, I can turn hard all day, even with throttle. At least, until power is pulled by the traction control...

 

[longliveSHO]

Some anecdotal evidence... use at your own discretion

I've been running the same "failed" PTU (as diagnosed by a Ford dealer) for over two years now, and 45k miles. When I first bought the car it took a week until I got a very faint gear whine at low-medium speeds and the classic dying gear oil smell in the cabin. I did some investigating and sure enough there was some delicious black, burnt grease in there with a TON of metal flakes on the magnet. Lovely.

Not able to afford the downtime and not wanting to afford the $2k job to replace it, I filled up the unit with new fluid and ran it for a couple weeks, let it puke out the vent, filled it again, let it puke out the vent, wash rinse repeat every oil change for about a year. The gear whine has lessened, and it's stopped puking out the vent so much since then.

That said - I also get a rumble/grind noticeable at parking lot speeds (heard and felt), especially when turning. I also suspect a CV joint/wheel bearing for that, although the PTU is constantly in the back of my mind. It's on borrowed time, after all.

Curious what your solution ends up being, will be monitoring this thread. Best of luck.

 

[ticoscen]

So, I did the tune. Flushed out the ptu one more time, now with a drain plug. And refilled with lightweight shock proof.

And decided to hold the break, and launch from 2,000 rpms.

And then smelled the dreaded gear oil in the cabin symptom. Went away shortly after, under more normal driving.

My question is this...when the PTU fails...what actually happens? And explosion of oil and metal? A grinding crunching of gears followed by no forward motion?

 

[ticoscen]

Prolly not blown yet. I drained mine at 120K and was very black and nasty. Added a drain plug with magnetic capabilities. Drained it 3 more times. It's working GREAT now. In my case, after the first drain and fill, I had grease/oil belching out of the PTU onto the driveway. That was because of the top PTU vent being totally clogged. You have to check that. Remove it, and put in the upgraded vent system that won't clogg. After I did that, PTU holds in oil, no belching and not smell. Just nice torque transfers to the rear at launch.