griggs95 Posted March 22, 2013 Report Share Posted March 22, 2013 I was going to have a shop replace this but they stopped since there was a service bulletin "The PTU is NOT to be drained unless contamination is suspected. To drain the PTU fluid , the PTU must be removed from the vehicle. The fluid that is drained may appear black and have a pungent odor. DO NOT mistake this for contaminated fluid." Note: A new PTU must be installed any time the PTU has been submerged in water. So with that I didn't have them touch the PTU with only 35k on my clock. I know people were talking on here about changing their's and I was wondering if I'm missing something? Quote Link to comment Share on other sites More sharing options...
bpd1151 Posted March 22, 2013 Report Share Posted March 22, 2013 I am not aware of the existence of such a bulletin. There are plenty of members here who have changed their PTU fluids, including myself. It is kind of a PITA as it has to be sucked out from the top of the housing, where the fill plug is located. Not changing the fluid makes about as much sense as choosing not to change your oil. Especially if you're tracking the car, or intend to track it. I would strongly reconsider and get it changed. Go to a different facility if need be as it sounds to me (w/o knowing more about the shop) that they were blowing smoke up your butt cuz they just simply didn't want to perform the service. Sent from my DROID3 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
griggs95 Posted March 22, 2013 Author Report Share Posted March 22, 2013 Thanks for the input, this whole PTU thing is new to me since this is my first car with it. It sounds like the shop I took it to doesn't know much about it to either. Do you remember what weight/brand of fluid you used to replace yours? I purchased Amsoil 75/140 Quote Link to comment Share on other sites More sharing options...
bpd1151 Posted March 22, 2013 Report Share Posted March 22, 2013 Yep, you got it. 18oz. Of 75/140. I use Royal Purple personally. Sent from my DROID3 using Tapatalk 2 Gjkrisa 1 Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 22, 2013 Report Share Posted March 22, 2013 Yea i took my car to the dealer and they did the service when they removed the fluid with a vacuum pump. Overall it was a quick inexpensive process. I'd say find another shop to go to. Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 22, 2013 Report Share Posted March 22, 2013 Do you remember what weight/brand of fluid you used to replace yours? I purchased Amsoil 75/140 Thats why i used before was Amsoil. I will be using Redline from this point on. Quote Link to comment Share on other sites More sharing options...
griggs95 Posted March 22, 2013 Author Report Share Posted March 22, 2013 Just curious why you'd switch to Redline? Did you find out something about that product that is better? Thanks Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 23, 2013 Report Share Posted March 23, 2013 A few factors. Luckily i have a AMSoil warehouse in town so i can easily get their products. But their hours are limited so it can be a pain sometimes to find the time to go get it. Redline is sold at a couple local speed shops hear and its much easier to get to them. Price is about the since and Redline is made of the high quality base stock that isn't fracked. Doesn't disclose what their base stock is made out of. Quote Link to comment Share on other sites More sharing options...
Blaine109 Posted March 23, 2013 Report Share Posted March 23, 2013 Good read/write-up with pics on changing PTU over at fordflex.net --> http://www.fordflex.net/forums/viewtopic.php?f=7&t=9334 SHOdded 1 Quote Link to comment Share on other sites More sharing options...
SHOdded Posted March 23, 2013 Report Share Posted March 23, 2013 Good read/write-up with pics on changing PTU over at fordflex.net --> http://www.fordflex.net/forums/viewtopic.php?f=7&t=9334 Good find, good reading! Quote Link to comment Share on other sites More sharing options...
griggs95 Posted March 23, 2013 Author Report Share Posted March 23, 2013 Blaine109, what an awesome link you provided. I really had no idea what a PTU did and how important good quality lube was since it holds so little fluid. I really think it should be changed every 35k or sooner depending on each Sho's daily use. I'm surprised Ford isn't recommending a fluid change on these sooner rather than later:noidea: Quote Link to comment Share on other sites More sharing options...
tss Posted March 23, 2013 Report Share Posted March 23, 2013 I am convinced. Taking a vacation driving to Washington DC first week in April.Going to try to get the scheduled before then. 54,000 on the clock. Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 23, 2013 Report Share Posted March 23, 2013 Good read/write-up with pics on changing PTU over at fordflex.net --> http://www.fordflex.net/forums/viewtopic.php?f=7&t=9334 Thanks, The inside of that unit looked horrible. That is why i change my drivetrain fluids annually. Blaine109, what an awesome link you provided. I really had no idea what a PTU did and how important good quality lube was since it holds so little fluid. I really think it should be changed every 35k or sooner depending on each Sho's daily use. I'm surprised Ford isn't recommending a fluid change on these sooner rather than later:noidea: Given our drivetrain is designed to be FWD when crusing and it only kick in when accelerating, corning or when slip is detected. Because of that the PTU for most people will not get used most of the time. Those of us who race the car use it a bit more, which is why i change my fluid much more frequently. Quote Link to comment Share on other sites More sharing options...
Carson Lomax Posted March 23, 2013 Report Share Posted March 23, 2013 Thanks, The inside of that unit looked horrible. That is why i change my drivetrain fluids annually. Given our drivetrain is designed to be FWD when crusing and it only kick in when accelerating, corning or when slip is detected. Because of that the PTU for most people will not get used most of the time. Those of us who race the car use it a bit more, which is why i change my fluid much more frequently. I believe this is a false assumption. The PTU is always engaged turning the driveshaft to the rear differential. Engagement of the rear wheels happens on the input side of the rear differential (after the PTU). FWD/RWD bias should have nothing to do with what's going on inside the PTU. Quote Link to comment Share on other sites More sharing options...
mjhpadi Posted March 23, 2013 Report Share Posted March 23, 2013 So can I safely assume that the fluid in the PTU is the same that is used in the differential? I've never really looked into changing but now that I have 22K on the car, I think it's time. I normally do drivetrain fluids at 30K intervals. I just want to make sure I get the right fluid for the change. Quote Link to comment Share on other sites More sharing options...
tss Posted March 23, 2013 Report Share Posted March 23, 2013 I am in no way knowledgeable in this area, but I think of it in the same way. Even thoug I may not have engaged my 4 wheel drive all that much when I had a 4 wheel drive Tahoe, I still replaced the diff fluids at the same intervals. I did not base my maintenance plan on how often I used the 4 wheel drive system. Quote Link to comment Share on other sites More sharing options...
bpd1151 Posted March 23, 2013 Report Share Posted March 23, 2013 So can I safely assume that the fluid in the PTU is the same that is used in the differential? I've never really looked into changing but now that I have 22K on the car, I think it's time. I normally do drivetrain fluids at 30K intervals. I just want to make sure I get the right fluid for the change. No, it's NOT the same Mark. The Rear Differential takes 2.4 pints of 75/90. Sent from my DROID3 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
tss Posted March 23, 2013 Report Share Posted March 23, 2013 Ford dealer is going to get my money on this 1...... Quote Link to comment Share on other sites More sharing options...
EcoBoostSHO Posted March 23, 2013 Report Share Posted March 23, 2013 No' date=' it's [b']NOT[/b] the same Mark. The Rear Differential takes 2.4 pints of 75/90. Sent from my DROID3 using Tapatalk 2 Do you happen to know if the rear diff fluid contains or needs a limited slip additive? Quote Link to comment Share on other sites More sharing options...
bpd1151 Posted March 23, 2013 Report Share Posted March 23, 2013 Do you happen to know if the rear diff fluid contains or needs a limited slip additive? Certainly not required (nor is it spec'd for it), but I suppose anything that would help out the primary fluid wouldn't be hurtful as far as an additive goes..... Quote Link to comment Share on other sites More sharing options...
EcoBoostSHO Posted March 23, 2013 Report Share Posted March 23, 2013 Certainly not required (nor is it spec'd for it)' date=' but I suppose anything that would help out the primary fluid wouldn't be hurtful as far as an additive goes.....[/quote']Thanks! I appreciate it. Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 23, 2013 Report Share Posted March 23, 2013 I believe this is a false assumption. The PTU is always engaged turning the driveshaft to the rear differential. Engagement of the rear wheels happens on the input side of the rear differential (after the PTU). FWD/RWD bias should have nothing to do with what's going on inside the PTU. From Fords site about their drivetrains. On-Demand All-Wheel DriveThe third type is the on-demand system. An on-demand system is always driving one axle and then drives the other axle as conditions demand. In the case of the Ford Fusion or Ford Edge, the front axle is the primary drive axle. For the Ford Explorer and Mercury Mountaineer, the rear axle is the primary drive axle.Simple mechanical systems use a clutch to send torque to the secondary drive axle when the primary axle starts to slip. Today’s electronic systems — like those found on all Ford Motor Company cars as well as Ford Explorer and Expedition, the Lincoln Navigator and the V-8 Mercury Mountaineer — use a computer controller that monitors such things as steering angle, accelerator pedal position and engine speed to provide the precise amount of torque, front to rear, as needed. “What’s really impressive about these systems is that they don’t just react to slip,” says Rodrigues. “They usually prevent that slip from occurring in the first place. By predicting slip and preventing it, the driver doesn’t feel the vehicle slipping and responding. The operation is seamless.” He says on-demand systems create a smooth, confident driving feel in all weather conditions with much better traction. The systems also help balance and improve driving dynamics by sending torque to the secondary axle when it’s most appropriate for handling. “On a normal front-drive vehicle, the front wheels have a limited amount of traction available to them,” says Rodrigues. “That traction has to be used for moving the car forward and for steering. If you use all of the torque to drive forward, you don’t have anything left to steer with, and vise versa. An AWD system off-loads some of that drive torque to the rear wheels. The harder you accelerate, the more of that torque that’s going to be redirected to the rear wheels, restoring the ability of the front wheels to steer the vehicle while providing an even higher level of acceleration.” This is what i was referring to. The rear wheels are only engadged when needed. That way we get FWD fuel economy, and AWD traction. Thats why our cars that are heavier & have more power than Evo and STi's gets much better fuel economy. Quote Link to comment Share on other sites More sharing options...
Carson Lomax Posted March 24, 2013 Report Share Posted March 24, 2013 From Fords site about their drivetrains. This is what i was referring to. The rear wheels are only engadged when needed. That way we get FWD fuel economy, and AWD traction. Thats why our cars that are heavier & have more power than Evo and STi's gets much better fuel economy. I don't disagree that our cars operate like what you've quoted from Ford's website. What I disagree with is the assumption that if the rear axle is not engaged, the PTU is not operating. Operation of the PTU is independent from engagement of the rear axle. The way our AWD system is designed the PTU is always engaged and the rear driveshaft is always turning, even if the rear differential is not engaged. Quote Link to comment Share on other sites More sharing options...
racerx78 Posted March 24, 2013 Report Share Posted March 24, 2013 The PTU is the engagement point for the rear axle, not the rear differential. The point of my comment and what is backed up by the article, is that the PTU does not engage the rear axle until slip is detected or under acceleration. So yes the PTU is always working but it isn't always engaging the rear axle/driveshaft. That way the amount of parasitic is reduced greatly. Quote Link to comment Share on other sites More sharing options...
Carson Lomax Posted March 24, 2013 Report Share Posted March 24, 2013 The PTU is the engagement point for the rear axle' date=' not the rear differential. The point of my comment and what is backed up by the article, is that the PTU does not engage the rear axle until slip is detected or under acceleration. So yes the PTU is always working but it isn't always engaging the rear axle/driveshaft. That way the amount of parasitic is reduced greatly.[/quote'] You need to read this thread: http://www.shoforum.com/showthread.php?p=1383636 Specifically post 34 that shows the rear axle sub-assembly with the differential clutch on the front of it and also post 42. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.