35% in a low speed tight accelerating turn could be a real problem.

But with a base FWD Ford really had little choice.

 

You are not the only one. My PTU went out yesterday. I was simply driving on a paved road and engaged the brake slightly to make a turn. Then the noises and clattering started. Towed it to a Ford dealer. $2256 to repair. 2005 model with 97,000 miles. I have never taken the vehicle off road, and up until recently I would have told you that this was the best vehicle I ever owned. Now I am not so sure. I have had two major issues, this one - the PTU, and then the left front wheel bearing went out. The dealer replaced it and then had to replace it again about a month later. I liked this Escape so much that my plan was to trade it for the Escape plug-in hybrid when it came out in a couple of years. But again, maybe not now...

 

Mine just went as well. 2007 MMH with ~54,000 miles. The noises started a week and a half ago. I replaced the U-Joints which didn't resolve the issue. While replacing the U-Joints I found some type of lubrication fluid on the side of the housing where the rear driveshaft met the transmission and a loose bolt that I could turn with my fingers (and rather difficult to get a wrench on it) so I tightened it and checked for fluid in the housing and there was some. After test driving I discovered that replacing the U-Joints didn't correct the issue so I took it in to a Service Center a week ago. The Service Tech told me all he could hear was road noise and he couldn't find anything else wrong with it. So I continued driving it and 5 days later the noises turned in to clanging and banging and I took it back in. After a couple of hours I was told my PTU needed to be replaced.

I then researched for PTU issues and found TSB 09-4-4 which described what I had found. The vent bolt on the PTU was lose and that was the fluid that leaked out. With only 12 ounces of oil in the PTU my guess is that this is where the problem origionated from. There was enough oil to lubricate the PTU but my guess is that the oil also acts as a coolant where it would splash up on the moving parts, drip down to the bottom aluminum housing (aluminum is great at moving heat) where the heat would be transfered through the housing to the air moving underneith the vehicle and then the cooled oil would get splashed back up on the moving parts again effectively cooling them. My guess is maybe a half of a cup (4 ounces) of oil leaked out the vent bolt. This would mean that the PTU cooling effecency was reduced by 33% and with the temperture above 90 degrees as it has been for the past 4 weeks (along with construction season's stop-n-go driving), it wasn't long before the PTU went in to thermal meltdown.

I know once my PTU is replaced, I'm going to check and top off the PTU fluid level at the beginning of every summer season and hopefully this will keep the PTU from failing again.

 

The new Ford Taurus X (aka: 2011 Ford Explorer) was at the Seattle auto show this past week. I couldn't get a good look at the undercarriage but from what I did see it appeared that both the PTO and the rear differential case were water cooled.

 

Well, well...a similar experience here. I picked up a flat tire (front right tire with a screw in the tread) on my 72,000 mile 2006 Ford Escape Hybrid July 30 and changed the tire with a spare.

That is when the problems started. As I backed out of the garage to take the flat tire to Les Schwab Tires to be patched/plugged, I noticed a definite "clunk" sound in the transmission and then what sounded like a "bag of gravel" in there. I drove to Les Schwab 30 miles away, fixed the tire, but still heard the "gravelly" sound in the transmission. I drove 30 miles home and the sound lessened. But, on August 1, the "gravelly" sound returned and so I drove to I-5 Ford in Chehalis.

They diagnosed the problem and told me I needed a new PTU. The good news was that I was covered under an extended warranty (otherwise that was a $2500 replacement cost), but the bad news was the unit was "out of stock and back ordered".

After two weeks of asking about the "back order" and the same response that "It was Ford's problem although they put the order on emergency", I called Ford's 800# Customer Care. They could not help me.

Finally, I asked I-5 Ford what the root cause of failure was and they said that if a tire is out of circumfrance with different depth of tread, for instance, that could cause the PTU to fail. But, they measured the tires on my Ford Escape and noted no difference with the tire tread or circumfrance. The Customer Care people confirmed that differences in tire tread could cause a PTU failure. I am still waiting to hear how Ford could release a car that required 4 tires to be replaced when one tire went flat.

Has anyone heard of this failure of a PTU when the tire treads (or circumfrances) differ?

 

Did you change to the compact spare? How far in total did you drive with the spare?

I don't have an answer, but those additional details might help somebody figure it out.

 

Hi Econoline:

Yes, I used the manufacturers compact spare tire and I drove 30 miles on the spare.

1. I heard the "gravelly" sound in the transmission throughout driving on the spare and with the patched/plugged original Continental tire (front left side).

2. The dealer said that he measured the circumfrance of the spare and it matched the front left side. But, I know the tread on the spare was new and the front left side, being original, had a worrn tread. I believe the difference in the tread caused the PTU to fail.

3. I have called Ford Customer Care in Dearborn, MI and their technicians tell me that a difference in the wear of the tires can make the PTU fail.

Story is still unraveling,

Ted

 

The PTU is nothing but a right angle drive. It does no differentiation, has nothing to do with the traction coupling to the rear axle, nor is it involved in the front wheel drives. The PTU takes power from the transaxle, turns it 90º and transmits it to the rear axle. If it was bad, it was bad from something else.

The Automotive world had been making differentials for a hundred years. The idea that a small difference in wheel outside diameter would cause what you experienced is just bogus. Teenagers have been driving around with any tire they could afford and of vastly different sizes for decades. Those differentials survived somehow.

What I am surprised at is that they appear indifferent to the possibility that your transaxle has been damaged. That's where the differentiation between the two front wheels occurred.

In the end, if Ford knew that using the temp spare (of a smaller diameter) would damage the drivetrain, why did they put it on the car to start with. That's bogus also.

 

Postscript: Drain the transaxle oil and see what comes out in the oil. I'd put in new oil on refill.

 

The "key" to this failure incident might have to do with just how long, how far, the Escape was driven with a partially flat front tire. The Escape PTU has bene proven to be less than robust historically and so it would take much driving distance to result in a failure after 70,000 miles of stress.