PTU, Trans, Or CV Axle noise

[Junkyard_Mad-Scientist]

I've noticed a faint gear-like noise coming from behind the drivers side firewall. I can only hear it with the radio off and hvac on low fan speed or off so it's very faint. It only happens when I have my foot barely on the pedal, it sounds like something engages and then it's like a gear whine only instead of a distinct whine it sounds like a blender.

Best case scenario if it's anything I figured maybe a cv axle, worst case trans or ptu, but since they're all right there I can't pinpoint it and it doesn't seem to do it at low enough speeds to ride on the hood.

It seems to be between 15 and 50mph i can hear it, feathering the throttle I can make it come and go (off the throttle fully no noise, slightly in the throttle it's back, fully in the throttle can't hear it because of other noise) it doesn't seem to get louder with speed or revs, it's a consistent volume and rhythm.

I did a ptu and trans fluid drain and fill about 15k ago with motorcraft lv and redline lwsp and planned on another round at my next oil change. There is no change in the cars performance, no slipping or binding, is this something to worry about/ look into? How, where? Or am I just being over sensitive to noise?

 

[luigisho]

You are over sensitive for good reason. These are known failure items. You are doing what can be done re: fluids. So best advice is hope for the best and plan for the worst (save for future replacement unit) or plan to sell it before anything too expensive goes awry.

 

[kryptto]

I've noticed a faint gear-like noise coming from behind the drivers side firewall. I can only hear it with the radio off and hvac on low fan speed or off so it's very faint. It only happens when I have my foot barely on the pedal, it sounds like something engages and then it's like a gear whine only instead of a distinct whine it sounds like a blender.

Best case scenario if it's anything I figured maybe a cv axle, worst case trans or ptu, but since they're all right there I can't pinpoint it and it doesn't seem to do it at low enough speeds to ride on the hood.

It seems to be between 15 and 50mph i can hear it, feathering the throttle I can make it come and go (off the throttle fully no noise, slightly in the throttle it's back, fully in the throttle can't hear it because of other noise) it doesn't seem to get louder with speed or revs, it's a consistent volume and rhythm.

I did a ptu and trans fluid drain and fill about 15k ago with motorcraft lv and redline lwsp and planned on another round at my next oil change. There is no change in the cars performance, no slipping or binding, is this something to worry about/ look into? How, where? Or am I just being over sensitive to noise?

Check both fluids closely or send the transmission out to Blackstone? The best case and I am hopeful it's the CVs at this mileage, check for split boots, or any black oil stains on the driveway. My hope is the axels on both sides need to be replaced at this point. Any full wheel turns left and right, then the same in reverse make it worse?

 

[Junkyard_Mad-Scientist]

New evidence to present, while backing out of a tight parking spot last night I turned the wheel to lock and it felt awfully crunchy, almost like a cv axle trying to pop out of socket so @kryptto theres sokething to suggest best case scenario.

On the ride home the sound was more noticeable, not really worse but I could hear it with the radio going.

Out of curiosity I used the useless awd gauge and saw something suspicious (I'll post visuals later) with my foot in of the throttle the indicators show front wheels "activating" first and then slowly the rear comes in. With my foot out of the throttle coasting the front wheel bars drop and go away, the rears however drop and stay "engaged". Does this mean anything? Maybe whatever sensor that gauge uses is showing torque or resistance from the ptu.

I'm going to try and find time today to at least snoop around under the car, no driveway so no way to see oil drips, but I swear this car smells money when it hits the bank. I bought brakes and my ac quit working yesterday too (I at least know what caused that)

 

[kryptto]

New evidence to present, while backing out of a tight parking spot last night I turned the wheel to lock and it felt awfully crunchy, almost like a cv axle trying to pop out of socket so @kryptto theres sokething to suggest best case scenario.

On the ride home the sound was more noticeable, not really worse but I could hear it with the radio going.

Out of curiosity I used the useless awd gauge and saw something suspicious (I'll post visuals later) with my foot in of the throttle the indicators show front wheels "activating" first and then slowly the rear comes in. With my foot out of the throttle coasting the front wheel bars drop and go away, the rears however drop and stay "engaged". Does this mean anything? Maybe whatever sensor that gauge uses is showing torque or resistance from the ptu.

I'm going to try and find time today to at least snoop around under the car, no driveway so no way to see oil drips, but I swear this car smells money when it hits the bank. I bought brakes and my ac quit working yesterday too (I at least know what caused that)

Well no experience with the AWD indicator, I wouldn't put much into that. Well if the boots split there will be splatter on surrounding chassis, etc. Try that all wheel left then right forward and reverse. Listen for the clicking and any binding. We are front wheels first, and passenger axle take off. That one goes first, good luck, and hopefully it's a double axle replacement.

 

[Junkyard_Mad-Scientist]

Checked it all out today, no fluids gushing out of anything, cv axles seems okay, slight movement but there is grease seeping out of the boots so I guess they're due anyway.

After poking around and wiggling the axles I took it for a drive did some figure 8s....no noise, warmed it up, pulled her hair a little, still no noise.

I'm betting on cv axle. Going to go with the TRQs on amazon (unless someone can telle why not) and do a ptu and trans fluid change early just for good measure.

 

[CraxyMitch]

New evidence to present, while backing out of a tight parking spot last night I turned the wheel to lock and it felt awfully crunchy, almost like a cv axle trying to pop out of socket so @kryptto theres sokething to suggest best case scenario.

On the ride home the sound was more noticeable, not really worse but I could hear it with the radio going.

Out of curiosity I used the useless awd gauge and saw something suspicious (I'll post visuals later) with my foot in of the throttle the indicators show front wheels "activating" first and then slowly the rear comes in. With my foot out of the throttle coasting the front wheel bars drop and go away, the rears however drop and stay "engaged". Does this mean anything? Maybe whatever sensor that gauge uses is showing torque or resistance from the ptu.

I'm going to try and find time today to at least snoop around under the car, no driveway so no way to see oil drips, but I swear this car smells money when it hits the bank. I bought brakes and my ac quit working yesterday too (I at least know what caused that)

This is exactly the operation you should expect. Front wheel bias AWD means your front wheels start, then the rear fill in and essentially just act like a backup. Deceleration: front wheels less, more drag on back wheels.
I think you're seeing what you should.

There's an off-chance you're hearing turbo whine for your sound.

 

[Junkyard_Mad-Scientist]

This is exactly the operation you should expect. Front wheel bias AWD means your front wheels start, then the rear fill in and essentially just act like a backup. Deceleration: front wheels less, more drag on back wheels.
I think you're seeing what you should.

There's an off-chance you're hearing turbo whine for your sound.

That's a good point, I probably just never noticed it since I rarely use the gauge

I had considered the noise to be coming from the turbo or even the BOV, maybe a bearing in the rear turbo is going out? But I have determined the sound only starts after about 20 minutes of driving regardless of warm up time. I let my car idle for about 10 minutes in the morning and there is still no sound until the drivetrain has been moving for about 20 minutes.

Its so faint (I would record it if I could but with road noise its difficult to hear it) its very hard to pinpoint and the fact that it goes away unless my foot is in the right spot on the throttle has me hoping its an axle but not ruling out the PTU. I would say maybe even a torque converter but I have never been able to hear one failing.

The best I can describe it is if you put ice in a blender, it has a inconsistent gravel noise and if I pump the throttle I can hear a coupling sound like a worn u-joint slapping back and forth. I have the axles and the fluids so I am going to take care of it this weekend and hope for the best. If the PTU or anything transmission related happens she's getting shelved for a few months, just spent a bunch of money getting my truck road worthy for a trip in April. the "Mistress" as my wife calls it, gets jealous when I work on other cars.

 

[Junkyard_Mad-Scientist]

So I didnt get around to working on the car this weekend, but friday coming home the noise got worse, it does it with my foot out of the throttle now. one thing I never considered was wheel bearing, Ill know more when I finally get it apart, for now im driving my truck. too paranoid that its my PTU getting ready to nuke

 

[Junkyard_Mad-Scientist]

Happy to announce that the strange noise appears to have been the cv axles. Both were replaced along with some seriously dirty ptu fluid and strangely clean transmission fluid.

 

[Junkyard_Mad-Scientist]

Spoke too soon, noise came back on the drive home. Saving for a ptu

 

[CraxyMitch]

Ooooh I wasted a like on your post.
Sorry to hear it. Unless you had the ptu from manufacturing in order to baby it, I think this one is coming for us all eventually.

 

[Junkyard_Mad-Scientist]

I think this one is coming for us all eventually.

Yeah ptu and water pump, my pump was done right before I bought it and now at 130k I guess the PTU wants its turn. Need to dig around and see what my options are as far as using a PP PTU, I'd like a drain and a cooler. But I'm going to check the intermediate shift and rear driveshaft too, the fact that it has to be warm to make noise has me convinced it's the PTU