Hi all,
Sorry for the length of this, but I figure detail is good for helping with diagnosis. Long and short of this is, has anyone experienced anything similar? Did you solve the problem? How? Thanks in advance for taking time to reply.
I've got an 03' Dak SLT club cab, 4.7, 5 speed auto, 2WD 214,000 miles, if that matters.
I'm stumped on this one. I have a high-pitched whistle/ squeal/ squelch noise coming from underneath the truck. It isn't really a whining noise though. It comes and goes randomly. I can hear it when traveling at highway speed, very faintly, and it will sometimes persist at low cruising speed until just before the truck comes to a stop. I can't recreate it for the life of me so I can listen around, even by having someone run it (secured and safe) up on jack stands. I have been trying to record it with my phone for some time now, when I do, ill add it here.
It DOES NOT vary with engine/ driveline speed. It is constant, and wavers slightly at about the same pitch, regardless of ground speed, RPM, or what gear the trans is in, except that it never occurs when the truck is stopped. It started last winter and was so faint you could barely hear it, and it rarely ever happened. It is getting steadily worse and more frequent. So far I've had my best listen to it after pulling off a parkway (50 mph) then driving down a shopping center back alley by the loading docks. I was going about 25 down the alley. The noise was definitely coming from underneath, and sounded like its more toward the rear. It stops right before the truck comes to a complete stop.
I just rebuilt the driveshaft with new MOOG u-joints because I had a squeak that sounded exactly like this all the time.
The joints were definitely bad. That noise has gone away, I carefully marked the yokes and bolts, and there are no vibrations. I don't think the noise is driveshaft related.
My thoughts so far are:
1. Loud fuel pump
- wouldn't a noise like this also be accompanied by fuel pressure issues, occur when the truck is stationary as well, and be easily recreated?
2. Transmission oil pump
- The trans acts fine, no slip or hard shifting. It has chirped a little during gear changes under full-throttle acceleration since it was new, but that could also be accessory belt slip. I changed the ATF, and both filters about 30,000 miles ago, and about every 45,000 miles before that. Fluid on the dipstick is still clean, and smells fine. They were cheaper filters, but they were all I could find. I'm probably going to go ahead and change the fluid and filters next week after payday, because its about due, and I'm curious. If my cheap filter is starving something for fluid, I don't want to prolong it any more.
3. Clogged catalytic converter
- I don't have any power loss, excessive heat, or other issues that are usually accompanied with this.
4. Exhaust leak
- I have had a small manifold leak and a leak before the muffler at the cheap clamp I replaced a broken one with for years (other stuff has gotten in the way of repairing these, and I hate exhaust work. You know how it is.)
5. Vacuum leak/ evap system component
- Could a leak detection pump make noise like this under vacuum only above idle? This truck has always been plagued by evap codes, namely P0440, P0441, and P0456. I currently have P0440, which also comes and goes. I think my leak detection switch, purge solenoid, or pump is bad this time. I have pored over all the vacuum lines and fittings, of which many have been replaced multiple times. I should check the fuel filler neck and vent hose come to think of it. The vac lines seem fine, but they leaked so much over the years, I bet moisture mixed with E10 fuel vapor has done a number on moving parts. The gas cap is also fairly new.
6. Rear axle bearing (9.25 limited slip)
- Wouldn't a pinion, carrier, axle, or other bearing back there change pitch with driveline speed and sound more like a growl or whine? This axle has had the dodge crush sleeve clunk going between P, R, or D for many years, and the limited slip is totally NFG but other wise it's fine. I don't think its worth tearing apart and spending $$$$ just because the clutches don't grab so well any more on this old truck. If I decide to restore it, ill rebuild it with a Detroit True-Trac then.
7. Rear brakes
- No heat issues here. I rebuilt one of the rear calipers after the phenolic piston broke into a million pieces during a brake job. Its been fine since though. It makes a terrible noise when you first hit the brakes in reverse, but that is also something it has done since the first test drive at the dealership.
Again, sorry about the length of this post. Thanks so much for taking time to read it. Any insight or something I may have missed would be appreciated.
Sorry for the length of this, but I figure detail is good for helping with diagnosis. Long and short of this is, has anyone experienced anything similar? Did you solve the problem? How? Thanks in advance for taking time to reply.
I've got an 03' Dak SLT club cab, 4.7, 5 speed auto, 2WD 214,000 miles, if that matters.
I'm stumped on this one. I have a high-pitched whistle/ squeal/ squelch noise coming from underneath the truck. It isn't really a whining noise though. It comes and goes randomly. I can hear it when traveling at highway speed, very faintly, and it will sometimes persist at low cruising speed until just before the truck comes to a stop. I can't recreate it for the life of me so I can listen around, even by having someone run it (secured and safe) up on jack stands. I have been trying to record it with my phone for some time now, when I do, ill add it here.
It DOES NOT vary with engine/ driveline speed. It is constant, and wavers slightly at about the same pitch, regardless of ground speed, RPM, or what gear the trans is in, except that it never occurs when the truck is stopped. It started last winter and was so faint you could barely hear it, and it rarely ever happened. It is getting steadily worse and more frequent. So far I've had my best listen to it after pulling off a parkway (50 mph) then driving down a shopping center back alley by the loading docks. I was going about 25 down the alley. The noise was definitely coming from underneath, and sounded like its more toward the rear. It stops right before the truck comes to a complete stop.
I just rebuilt the driveshaft with new MOOG u-joints because I had a squeak that sounded exactly like this all the time.
The joints were definitely bad. That noise has gone away, I carefully marked the yokes and bolts, and there are no vibrations. I don't think the noise is driveshaft related.
My thoughts so far are:
1. Loud fuel pump
- wouldn't a noise like this also be accompanied by fuel pressure issues, occur when the truck is stationary as well, and be easily recreated?
2. Transmission oil pump
- The trans acts fine, no slip or hard shifting. It has chirped a little during gear changes under full-throttle acceleration since it was new, but that could also be accessory belt slip. I changed the ATF, and both filters about 30,000 miles ago, and about every 45,000 miles before that. Fluid on the dipstick is still clean, and smells fine. They were cheaper filters, but they were all I could find. I'm probably going to go ahead and change the fluid and filters next week after payday, because its about due, and I'm curious. If my cheap filter is starving something for fluid, I don't want to prolong it any more.
3. Clogged catalytic converter
- I don't have any power loss, excessive heat, or other issues that are usually accompanied with this.
4. Exhaust leak
- I have had a small manifold leak and a leak before the muffler at the cheap clamp I replaced a broken one with for years (other stuff has gotten in the way of repairing these, and I hate exhaust work. You know how it is.)
5. Vacuum leak/ evap system component
- Could a leak detection pump make noise like this under vacuum only above idle? This truck has always been plagued by evap codes, namely P0440, P0441, and P0456. I currently have P0440, which also comes and goes. I think my leak detection switch, purge solenoid, or pump is bad this time. I have pored over all the vacuum lines and fittings, of which many have been replaced multiple times. I should check the fuel filler neck and vent hose come to think of it. The vac lines seem fine, but they leaked so much over the years, I bet moisture mixed with E10 fuel vapor has done a number on moving parts. The gas cap is also fairly new.
6. Rear axle bearing (9.25 limited slip)
- Wouldn't a pinion, carrier, axle, or other bearing back there change pitch with driveline speed and sound more like a growl or whine? This axle has had the dodge crush sleeve clunk going between P, R, or D for many years, and the limited slip is totally NFG but other wise it's fine. I don't think its worth tearing apart and spending $$$$ just because the clutches don't grab so well any more on this old truck. If I decide to restore it, ill rebuild it with a Detroit True-Trac then.
7. Rear brakes
- No heat issues here. I rebuilt one of the rear calipers after the phenolic piston broke into a million pieces during a brake job. Its been fine since though. It makes a terrible noise when you first hit the brakes in reverse, but that is also something it has done since the first test drive at the dealership.
Again, sorry about the length of this post. Thanks so much for taking time to read it. Any insight or something I may have missed would be appreciated.
