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Discussion Starter · #1 · (Edited)
Looking for help/suggestions please!

The problem I have started the moment I pulled out of Boulder’s dealership after a transmission leak fix and is a scratchy noise that changes with RPM the is best heard from the drivers side echoing out of the side heater/ac vent. The transmission oil pan had just been replaced for a leaky seal & grommet that leaked trans fluid all over the bottom side of the truck/gas tank clear back to the rear bumper. Unknown volume of fluid has leaked out. Passenger rear axle was also replaced under warranty at the same time I found out.

The noise only occurs on startup after the truck has been cold and last for about 7 minutes (which concurs with the repair, since it didn't have any miles past the "check in" mileage at the dealership). The noise 1st started happening at about 2000 RPM and only under load driving it (won't occur just revving the engine in park or neutral). Since then, 2 months later and coming up on a month the Longmont dealership has had it, the noise happens all the way up to redline RPM now, including a little on the RPM delceleration after a shift or redine.

A few facts about the scratching/metallic noise (hopefully someone might recognize the problem):
1) 2015 Dodge Ram 1500 Sport, 5.7 liter, 8 speed 8HP70 transmission
2) Began immediately after having the plastic transmission oil pan replaced under warranty at ~4000 miles
3) Only happens on a cold overnight startup for about the 1st 7 minutes of actual driving when under load accellerating and gradually lessens as the transmission temp approached 150 degrees. Doesn't matter if in 2WD or 4WD.
4) Started happening at around 2000 RPM for about a 200-300 RPM window and is not gear specific, happens in reverse also, but MUST be under load (not in Park or Neutral)
5) Now at over 6000 miles the RPM range of the noise happens closer to 2500 RPM and can continue all the way to RPM Redline.... but the noise can be avoided by driving with less load (accelerate slower up to redline)
6) All components driven by the serpentine belt have been ruled out by driving a short distance with the serpentine belt remove and noise still occurred.
7) Truck was recently anchored to a 3' wide tree stump and the noise occurred at about 2500 RPM (until the ECU started rev limiting it to lower than 2000 RPM). So this test ruled out any noise from differentials/CV shafts/drive shaft/brakes/wind/etc.)
8) Letting the truck warm up 15 minutes in the driveway before driving, still gets about 7 minutes of actual driving noise that can be generated. Again, seems more dependant on transmission temp than coolant and oil temps.
9) Entire instrument cluster was removed by dealership to test the possibility of "stepper motors" in the instrument cluster making the noise. The noise actually got worse.... probably due to the cluster muffling the noise.
10) Truck was warmed up for 45 minutes before driving with trans temp up to 163 degrees, 199 coolant, 192 oil and noise could not be replicated (only 1st drive of the day situation in which the noise didn't occur)
11) Truck has been used 3 times to haul a 4100 lb car on an open U-haul car hauler, for an 80 mile round trip with no problems till the tranny leak was noticed during an oil change. (so a mere 240 miles total of trailering for a truck with 3.92 rear gears and rated at 10,000 max towing per the VIN# lookup on Ram’s website)

Besides suspecting the transmission still, the only other possibilities I can think of is:

A) Possibility the brake booster or brake booster check valve could be making the noise? Might seem RPM related, but actually vacuum related.... which would change with RPM. (might try to clamp off the vacuum line and see what happens)

B) Servo motors inside the dash ventilation system freaking out till warmed up? (but doesn't seem as likely since only happens in 1st 7 minutes or so of actual driving and 15 minute warmup didn't change the outcome)

I've been dealing with this since before Thanksgiving and just started having a more reputable dealership in Longmont, CO start looking at it in early January when the roads were clear (so not to possibly mask the noise). Coming up on a month with no truck, so any suggestions are welcome. Thanks! :4-dontknow:
 

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This is a long shot but check your exhaust system. There is a piece of metal over a clamp that barely rests on the pipe. In certain conditions this could cause noise, vibration similar to what your are talking about. Just bend it back like in the photo.

 

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Discussion Starter · #3 ·
This is a long shot but check your exhaust system. There is a piece of metal over a clamp that barely rests on the pipe. In certain conditions this could cause noise, vibration similar to what your are talking about. Just bend it back like in the photo.

Thanks, I'll check it out. I did some looking around for that kind of stuff, but maybe overlooked that particular clip. Hopefully will be posting a dropbox video link in a bit too.
 

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Discussion Starter · #7 ·
Most dealerships have a device that they attach to a vehicle, it detects hard to locate noises.
They attach it & let you drive the vehicle, then they can review the results, sometimes they have to move it to another location

The device is called CHASSIS EARS

www.youtube.com/watch?v=6mpNRJ7m-c8
www.youtube.com/watch?v=JN7Slcugpl4
Fantastic tool - thanks for the recommendation! I actually ordered a set for myself to use on suspension stuff.

By using your suggestion, the dealer was able to verify the noise was definitely the transmission. Pulled the pan & found metal in the fluid. New transmission is arriving today.
 

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Discussion Starter · #9 ·
So.... the "chassis ears" did locate the problem and the noise was coming from the transmission. Dodge ended up replacing the transmission with a new one. Lots of metal in the fluid. Had it tested by BlackStone labs and iron content was something like what would have been expected at about 60k miles...... yet had about 2k miles on the fluid and new filter
 
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