Burning Smell?

[hankmack]

2011 don't have this problem? It's miner fix anyway .....

 

My 2011 had the problem at 1500 miles. New seals were installed and still OK at 3500 miles.

[curio]

I cannot believe the '11's are still having this issue ! Why doesn't Ford just ditch the PTU design and use the design of another car manufacturer. This is utterly ridiculous. I am so glad I did not go with the AWD.

 

Ford designed their own AWD system inhouse so they didn't have to license the tech from another company's design. Unfortunately their design is quite a bit less superior than most; for instance Ford's isn't symmetrical and is in FWD most of the time until slip is detected.

[akirby]

Ford designed their own AWD system inhouse so they didn't have to license the tech from another company's design. Unfortunately their design is quite a bit less superior than most; for instance Ford's isn't symmetrical and is in FWD most of the time until slip is detected.

 

Not true. Ford's system is electronically controlled and can split torque front and rear at any time. It transfers torque to the rear when accelerating through a turn e.g. or if you nail the throttle from a standstill - before slip occurs.

 

It's better than a mechanical system that only transfers torque when slip is detected but it's not as sophisticated as others that can also split torque side to side.

[curio]

Not true. Ford's system is electronically controlled and can split torque front and rear at any time. It transfers torque to the rear when accelerating through a turn e.g. or if you nail the throttle from a standstill - before slip occurs.

 

It's better than a mechanical system that only transfers torque when slip is detected but it's not as sophisticated as others that can also split torque side to side.

 

I never suggested that it couldn't electronically detect slip or that it couldn't split torque to the front and back. What I said was that Ford's AWD system is not a symmetrical AWD system - it is a FWD-based AWD system. This is why the Edge has a PTU, where as symmetrical AWD vehicles do not.

 

This type of system in our Edge's will send up to 50% of its driveline torque to the rear wheels when needed. Until that point though, most of the torque goes to the front wheels until needed otherwise. In other words, it is biased towards the front wheels - but at a moment of need the rear wheels can receive anywhere from 25-50% of the available torque.

 

The downside of this type of system is that it is still culpable to potential understeer, because even though the AWD tries to compensate when needed, the system still sends most of the torque to the front wheels most of the time.

 

In contrast, symmetrical AWD systems do not have a front (or rear) bias, they do not keep the torque in either front or the rear for most of the time. It adapts constantly between the front and rear, and does so more often. It also does not have a transfer case or PTU - instead they have what they call a viscous coupling center differential - which is similar in a way, but is clutch based instead of a lock in gear type. This allows for in a nutshell, all wheels powered at all times with no bias.

 

Symmetrical AWD also has the advantage of being able to send up to 75% of the torque to the front or rear wheels (compared to Ford's 50% to the rear). For instance, it can send 75% to the rear for acceleration and 25% to the front for direction changing agility. Ford's AWD system cannot do this since it is always bias towards the front - at best the Edge can make it 50/50; but it cannot give the rear more than the front.

 

Edit: There are vehicles that have RWD-based AWD systems too, like the Nissan GTR.

Edited August 21, 2011 by curio

[akirby]

Ford's isn't symmetrical and is in FWD most of the time until slip is detected.

 

You said it's in FWD until slip is detected. That's the part that isn't true. Ford's programming takes into account steering angle and throttle position and will send power to the rear before slip occurs - to prevent slippage.

That's all I was saying.

 

As for only sending 50% of the power to the rear, Ford has reported in the past that it could send up to 97% of the torque to the rear if necessary, but I can't find any links right now.

[curio]

You said it's in FWD until slip is detected. That's the part that isn't true. Ford's programming takes into account steering angle and throttle position and will send power to the rear before slip occurs - to prevent slippage.

That's all I was saying.

 

When I said 'until slip is detected' I meant the same thing as you just said - 'before slip occurs'.... ie it is proactive.

 

I can see how you can take what I said the wrong way though - 'before slip occurs' is a more proper way of saying it because like you say, it doesn't wait to detect slip since it accounts other factors like vectors and throttle position.

 

As for only sending 50% of the power to the rear, Ford has reported in the past that it could send up to 97% of the torque to the rear if necessary, but I can't find any links right now.

 

For short periods. It still is not symmetrical, and it has a clear front wheel bias. This system was based off of a Land Rover design when Ford used to own them - and about 97% of the torque goes to the front wheels most of the time when there is no need for AWD, but the rear wheels can accept up to 100% of the torque for short periods when needed. And I'm talking milliseconds. On average, the rear gets at best 50%.

Edited August 21, 2011 by curio

[mbct]

Well this is depressing, to say the least. I just returned from a 1,700-mile trip in my 2007 AWD and encountered the infamous burning oil smell at about 1,200 miles. Nothing obvious until I got home and put the beast up on jackstands to get all the way under it. RH halfshaft is leaking oil coming out of the PTU. I have a heatshield there, but the oil collects on the heat shield then dribbles onto the hot exhaust from time to time. Unfortunately, this Edge has 69,000 miles and just had the 2nd wheel bearing replaced (paid out of pocket, as the PT warranty has now expired). Has anyone had success at getting a dealership or Ford to stand up to the problem after the formal warranty expired? The downside to driving fairly gently and doing regular maintenance seems to be that the major problems get deferred until just after all the warranties expire.

[Johnathan Hall]

Well back in the shop here in Germany yet again...4 more months then it will be shipped back to the USA and i can get rid of it!!!

[Johnathan Hall]

So...After all these visits to the Ford dealership here in Germany they have had it for the past week trying to fix it. This time they had a guy from the ford factory come and look at it after the work was completed, and what do you know....it was already leaking again!!! so now finally Ford is paying for a rental car and ordering more parts....so ready to get rid of this thing!!!

 

By the way...they are replacing the seal and the passenger side axle this time....

Edited November 23, 2011 by _12780

[curio]

Ugh; well I think my PTU leak is back - at least it smells like it. This is on the new PTU that was installed last year after the dealer got sick of putting in new seals every month. I'm fed up with taking it in; I'll probably trade it for a different vehicle.

[Johnathan Hall]

well all said i have had multiple seals, a new PTO and a new passenger side axle. as of now the leak has returned since they replaced the axle. I am still not ready to take it on once the warranty ends so as we speak i am in the process of getting it sold so i don't have to deal with it anymore...good luck with whatever way you choose!