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eubie5

PTU'S leaking

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hey guys, just joined, and already my 1st post is a newbie question. 

drove 2.5 hours Saturday to look at a 2012 awd mkz w/60000 miles, at a Lincoln dealership. BEAUTIFUL. They told me the PTU was being replaced under warranty. i didn't know what that was, so i got home, and visited mr. google. 

now, i'm wavering on buying it, because i see some posts, and it seems this is an AWD model problem. is that correct? i've never even heard of a PTU. i know the part they replace is warrantied, but some people say their's continue to leak again. researching this led me down a rabbit hole where i discovered this car has an internal water pump, with a repair bill of 1500-2000. put some more fear in me, but that failure doesn't seem as common.

i'll probably end up buying it, because i love these cars, and they can be bought fairly cheap and in good shape, but just wondering about these maintenance issues.

thanks guys, love the site

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Welcome to the forums eubie5!

 

Time for a little helpful education then: The PTU is known as a Power Transfer Unit in an AWD system, and is important to send power to those rear wheels when its needed. For Ford and Lincoln, up to 50% of engine power and torque can be sent to the rear wheels (new torque vectoring vehicles can do up to 70%) and is done intelligently, as in the vehicle transfers based on wheel traction detection.

 

The problem with a lot of AWD vehicles between Ford and Lincolns is the PTU gear fluid gets neglected on being changed properly. Ford at first even coined this fluid as being "lifetime". There is no such thing as a "lifetime fluid". Lifetime means "till the warranty ends" among vehicle manufacturers.

 

The gear oil in the PTU starts to breaks down and loses its effective protection properties around 25,000 - 30,000 miles, or sooner depending on vehicle use and driving style. But many owners of these AWD vehicle will not have the fluid change and even mechanic shops will not change the fluid because "it's not suggested by the manual". So this 2012 MKZ at 60,000 miles probably did not get a proper PTU fluid change done...hence its fate.

 

Anyways, when the gear oil is worn out, the seals become more vulnerable to heat and friction wear. Eventually, the seal weakens and your leaking begins. The PTU is built "sealed" like the transmission is, and therefore instead of cracking open the case...its more favored to just replace the whole dang thing if the seal leaking gets too bad. Sometimes the outer seals only need replacement, but there are internal ones that pretty much doom the unit if they go.

 

The other thing is most units do not have a drain plug (I have heard some vehicles do have it) and require siphoning the fluid from the fluid fill plug instead, in order to perform a fluid change. It's not too hard to DIY if you know what to look for and have the right tools.

 

You will also have a RDU (Rear Differential Unit) that is a part of the system and helps manage power and torque going to the rear wheels. It too has gear fluid that should be changed around the same interval as the PTU for better lifespan.

 

If you get a brand new PTU unit, simply just keep this in mind to not let the vehicle's gear fluid go bad and you should be fine. The same goes for the water pump and coolant system.

 

Good luck on your MKZ should you choose to buy it!

Edited by Zalvern

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The PTU in my 2014 MKZ began leaking with only 23K on the clock. 

 

The fact that the PTU's been replaced is actually an incentive to buy it, IMO. You shouldn't have to worry about it for a while, especially if it's a whole new unit as opposed to them repairing it with a seal kit.

 

Yes, the 3.5 Duratec in the MKZ has an internal water pump and it's very expensive to replace.  The good news is that failures don't occur all that often and the ones that have failed did so at high mileage.  Is this a CPO vehicle?  You said it has 60K miles, which is Lincoln's limit for a CPO. It's also the limit for the original powertrain warranty. If it does have 60K, how are they repairing it under warranty?   If it is CPO, there's extended warranty coverage. 

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