Whining on Deceleration

[Dehaka]

96 f250 5.8 351w 64xxx miles 2wd e40d

truck was smashed from the back on 2021. insurance fully rebuilt rear end with some used parts. got back with at 573xx miles.....now has 64xxx miles. just got new oversized tires 305 70 r16 toyo at (just ran same tires to 50k, oil changed w pennzoil plat hm 10w 30, tranny 100% fluid change with Mobil D/M and fram filter, rear differential fluid changed w synthetic valvoline.
All work done by licensed shops.

truck makes a steady whining, groaning, almost identical to howling wind. noise most noticeable on deceleration. shifts perfectly fine, trans and oil at exact spot on dip sticks. nothing wrong with drivabulity thus far. want to fix noise before it turns into something bad. sounds like its coming from the rear of the vehicle when i stick my head out the window.
where should i begin looking? ideas as to what these symptoms sound like?

Thanks in advance for any replies.

 

[PontiacHO]

Pinion nut could have backed off. Was the differential overhauled or replaced with LNQ unit? Either way I’d think you are covered under warranty via the insurance company repair clause.

 

[dnewton3]

I suspect the ring/gear setup is not good from the rebuild.
Have the backlash and engagement checked soon.

 

[Dehaka]

Pinion nut could have backed off. Was the differential overhauled or replaced with LNQ unit? Either way I’d think you are covered under warranty via the insurance company repair clause.

according to that shop....they found another truck like mine with low miles and swapped out the whole axle. they painted the differential black....but now paints chipping off revealing some rust on the differential so it could be an old one.

 

[D60]

I would also suspect R&P

The rear driveshaft is worth looking at only because it's so easily done but I think u-joints, carrier bearing or even pinion angle are unlikely to cause your symptoms... if it's happening even at lower speeds.

 

[Lubener]

The pinion preload should be checked. It's an involved and tedious adjustment made with the pinion nut. Don't just retorque the nut without checking.

 

[i6pwr]

When they replaced the rear axle, any idea on how long the replacement sat, or just the overall history?

I would definitely document the noise before you start wrenching on it, even if you wanted to pull the rear cover, let them look at it first.

Could have had old/contaminated fluid, water, rust, who knows...and now it's showing it's face.

 

[D60]

When they replaced the rear axle, any idea on how long the replacement sat, or just the overall history?

I would definitely document the noise before you start wrenching on it, even if you wanted to pull the rear cover, let them look at it first.

Could have had old/contaminated fluid, water, rust, who knows...and now it's showing it's face.

My thoughts as well. They called a junkyard, bought a rear end that looked like a rear end, and installed it.

 

[D60]

Also not that you should have to deal with it, but I've got a 3.55 10.25 out back you could have for a song.....but realistically there's zero reason you should need to cross state lines to find a suitable candidate

 

[Dehaka]

When they replaced the rear axle, any idea on how long the replacement sat, or just the overall history?

I would definitely document the noise before you start wrenching on it, even if you wanted to pull the rear cover, let them look at it first.

Could have had old/contaminated fluid, water, rust, who knows...and now it's showing it's face.

I've owned the truck since 17 k miles. serviced all driveline stuff bi yearly. They kept my truck for 16 months which is why i am dreading taking in back to this shop. It has a notoriously shady reputation around town for keeping vehicles a long time but it is who Geico sent me to.

The fluid was just changed last month.

 

[i6pwr]

The fluid was just changed last month

From what I understand, you have about 7K miles on the replacement rear, and the fluid was changed last month.

When did you start hearing the noise on decel, in relation to when you had the rear replaced, and/or when the fluid was changed?

Just looking for a timeline of this noise.

Would be a good idea to double check the pinion yoke for movement, along with the nut to see if the nut is tight.

 

[Dehaka]

From what I understand, you have about 7K miles on the replacement rear, and the fluid was changed last month.

When did you start hearing the noise on decel, in relation to when you had the rear replaced, and/or when the fluid was changed?

Just looking for a timeline of this noise.

Would be a good idea to double check the pinion yoke for movement, along with the nut to see if the nut is tight.

yes. i had it changed 7/13 tranny, power sterring, diffirential, and oil, coolant a week before that. just did all 4 of my cars in 1 shot.

i used pennzoil platinum hm 10w 30 and thought it was just due to using different brand of oil. ....but figured after a while that oil dont cause whining noises......sounded more like gear noises. i noticed was primarily on deceleration that i detected it. stuck my head out window on freeway last night (no one else on road at 4 am) and i could still hear it still at 60 on cruise control.


im guessing i noticed it about a week or so after fluid service.

i got the truck back november of last year. been running great since then.

 

[i6pwr]

i used pennzoil platinum hm 10w 30

For the rear differential? I sure hope not.

 

[Dehaka]

ok just took it for a road test. the noise is also present upon acceleration and only occurs when the vehicle reaches operating temperature.

 

[Dehaka]

For the rear differential? I sure hope not.

no for the engine.

 

[i6pwr]

Ha, ok...so the rear has 7K on it since replacement and you haven't changed the fluid correct?

If so, I would open the fill hole and see how much fluid is in the diff.

If the fill hole is a recessed, square 3/8" opening, make sure you get a small pick in there and clean it out, so your breaker bar or extension will bottom out.

Check to see how far below the fill hole the oil is. You could roll up a piece of paper towel and dip it in there to gauge the color of the fluid.

 

[DuckRyder]

Does it also make noise on float? (constant speed)

It sounds like a ring and pinion problem,

 

[Dehaka]

Ha, ok...so the rear has 7K on it since replacement and you haven't changed the fluid correct?

If so, I would open the fill hole and see how much fluid is in the diff.

If the fill hole is a recessed, square 3/8" opening, make sure you get a small pick in there and clean it out, so your breaker bar or extension will bottom out.

Check to see how far below the fill hole the oil is. You could roll up a piece of paper towel and dip it in there to gauge the color of the fluid.

the diff fluid was changed when i did the other fluids on 7/13

 

[i6pwr]

the diff fluid was changed when i did the other fluids on 7/13

im guessing i noticed it about a week or so after fluid service

I would verify the fluid level, I don't think it will make a difference at this point if you can hear noise anyway but we need to verify fluid level.

The fact it happened shortly after the fluid service might tell a story.

 

[i6pwr]

Maybe since you have a full-float axle, you could pull the rear wheels and look for any fluid leaks around the hubs. If so, you could have some worn tapered roller bearings, check for any slop in the hubs, up and down.

Either way, you want to check the diff fluid level and condition.