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FYI, I have entered the what the gently caress phase of diagnosis. I have taken this to a shop and after weeks of off again on again efforts they were like... Uh, dunno. Maybe toss a new transfer case into it? A used low-mileage T case can be acquired for about $200, but I'm sick of throwing money at this thing. I have a 2007 Jeep Liberty Sport (white) with 157k on the clock that hums at interstate speeds. It's not super loud, but it's there and it's obvious. There is absolutely no sound at 70 MPH, but once I cross the 75MPH threshold she starts humming. It sounds like the woofers are stuck on at like a low E or something. This started last winter, maybe November. The weirdest part of this whole problem is that I'd never had this noise, then one day when I got onto the interstate IT WAS LOUD AS gently caress. It was so loud I almost turned around, but since I was heading out to buy a table saw at a good price goddamn it I kept going. After a few miles (and doing exactly nothing other than driving) the hum died down. To be specific at first I was like holy poo poo this thing is going to blow and I'm going to die and I won't be able to hear anything other than this loving hum while that happens, and then it changed to "I don't think I would really notice this unless I had the radio off." One second loud, the next soft. Has stayed soft ever since. 1. The noise is tied to speed (75+ MPH) seems to quiet down over 90 MPH (or when the Jeep thinks its going over 90, the speedo isn't super accurate)but y'know I'm not usually going over 90 in my 10 year old hunk of poo poo. 2. The noise occurs when the vehicle is accelerating, while it is coasting, and while it is decelerating 3. The noise is tied to vehicle speed and not engine speed 4. The noise is accompanied by some vibration that can be felt inside the vehicle on the gas pedal and on the center console, but it's not overwhelming 5. The noise started sometime after some service was done (Not trying to blame the shop, it's just when it started) I think the front diff was serviced (fluid) and the rear pinion seal was replaced (had been leaking). 6. The front prop shaft was replaced, the rubber boot at the front of the new prop shaft went bad, and it was replaced again. Both the front and rear shafts were sent to a driveline shop for balancing. The rear is out slightly but I guess they can't do anything more with it. 7. IIRC the Jeep still makes the noise even when it was driven with the front prop shaft removed. (The shop guy tried this I think). 8. I had the front tires balanced after the noise started, no help 9. I replaced the driver's side half shaft, no help 10. Feels/sounds like it's coming from the center of the vehicle, but because it's a low hum it's really hard to pinpoint. They had it on a lift and even then it was hard af to figure out. So, my guess is either something is bad in the a. transfer case, b. output of the transmission, c. differential pinion bearings. But if I'm honest I have no clue.
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Sep 6, 2017 22:44
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| # ? May 5, 2024 22:43 |
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UPDATE: I took this to another shop and they suspect that I might have a tire issue. They scoped the diff, did a bunch of other stuff, then swapped the tires front to back. They said they think it sounds different, I also think it sounds different but it's not a huge change. Maybe sounds like the hum is coming from the front passenger side now instead of it sounding like it was coming from all over. So - if anyone is still interested in this - do you think it's possible that a bad tire could cause this issue? The shop said they didn't think that there'd be any real problem, so they'd just drive it until it developed further. There's a big part of me that wants a solid diagnosis and cure, but I don't want to risk spending a bunch of money on a full set of tires. Would it make sense to buy a used set with good tread on them? I know nothing about buying secondhand tires... but it looks like I can get an aluminum set of wheels with decent rubber for like $200 all together. This WOULD be an upgrade as I currently have steel wheels... but like I said I have no idea how to shop for rims/used tires. Mostly I deal with old motorcycles.
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Sep 22, 2017 22:17
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Vegetable Dumpling posted:It was so loud I almost turned around, but since I was heading out to buy a table saw at a good price goddamn it I kept going. Priorities. Anyway, my first guess would also be tires. If you have the $200 to spend then yeah get the wheelset otherwise just wait until the problem progresses and you can have an actual diagnoses. If the vehicle isn't pulling it's probably not alignment. Second guess would be suspension components. When you go over bumps try and see if there's a hollow thump from any corner. Without a wobble or pull it'll be really hard to diagnose the problem and you'll spend money on trying to prove whatever mechanic's theories. Tire swap would be the easiest way to check. If you're hard up, I'd even maybe swap a spare on a corner at a time and see when/if the noise goes away. If it's one bad tire or whatever then you could narrow it down. It would be a lot of work and I personally wouldn't goes to those lengths for a hum.
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Sep 22, 2017 22:24
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Breakfast Feud posted:Priorities. It actually dawned on me after I updated that I have a full spare on the back of this tub of poo poo, and I've been swapping it around. It's not in great shape, but what the hell, it's DIFFERENT. My suspicion (and that of the shop's) is that it was one of the front tires, so I started there. Seemed to get a bit better (but not all the way better) when I put it on the passenger's side. Then I put the tire that had been on the passenger's side onto the driver's side (I left the spare on the passenger's side) and it seemed to mostly back to how it was. If it is the tires I think I've got a couple of baddies, and one of them is more bad than the other. Test not 100% conclusive. I can spare the $200, but it's an hour or so drive through Denver to get there. Between that and not being sure if I'll actually have this thing fixed I'm on the fence about picking them up.
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Sep 22, 2017 23:59
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Okay. Now, I need you to put the back tires on the front and a front + spare on the back.
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Sep 23, 2017 00:16
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Breakfast Feud posted:Okay. Now, I need you to put the back tires on the front and a front + spare on the back. Hold up, my neighbor (who I don't know) has a Jeep. Probably in the middle of the night tonight I could go and steal just one of their wheels and then put the spare plus one of neighbor's wheels on MY jeep (obv. one in back and one in front). I think I can get through it before he notices because I'll take my air compressor, a generator, and the impact wrench.
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Sep 23, 2017 00:23
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my dude, do it, take pics and report back
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Sep 23, 2017 01:36
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You could possibly eliminate the tires being the source by running it in 4wd in the air. Turn off the TCS and run it up to 80 mph and see if the noise is still there. If the noise is still there get a stethoscope and check all four hubs, both diffs, both transfer case outputs, etc.
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Sep 23, 2017 04:09
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I could get all four off the ground here, but I'm not really set up for that kind of thing. I guess I could see if the noise is still there with the tires off the ground, and then see if it's there with the rears spinning or just there with all four turning... but I don't know that I could get her lifted high enough to crawl around under there if I find a scope. I'm trying to avoid going back to the shop because of the money thing, they seemed to think it was tires and kind of shrugged. I'm getting a bit sucked into this thing because I've been hunting for months and want a real answer/solution. TBH I could probably just let it go and run it for another 6-12 mos without incident but I want to be sure it's going to handle the 1500 miles I want to put on it when we drive cross country for xmas. Shop said they scoped the rear diff when I had it in, and I'd assume I'd hear a hub or wheel bearing at lower speeds, right?
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Sep 23, 2017 18:24
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You can lift the car up a corner at a time and check the wheels for play. Basically grab the tire at like 3 and 9 and move it back and forth/side to side. It shouldn't have any play. If it does, it's your bearings.
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Sep 23, 2017 20:10
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Breakfast Feud posted:You can lift the car up a corner at a time and check the wheels for play. Basically grab the tire at like 3 and 9 and move it back and forth/side to side. It shouldn't have any play. If it does, it's your bearings. I could check that. Progress has slowed since this rain came in. We're not used to it here and I'm scared of it and not sure what to do about it. TBH, though, this thing has been in the shop like 4 times in the last six months as mechanics tried to diagnose this. I'm pretty sure they've already looked at this.
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Sep 23, 2017 20:27
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https://youtu.be/v-cXGo77PiE Does it sound like this? Because- I'm amazed too, believe me- the comments on this video seem like a decent head start.
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Sep 24, 2017 08:02
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glyph posted:https://youtu.be/v-cXGo77PiE No, it's actually really different from that. The pitch never changes. I've debated on taking a vid or recording of the sound but I don't think it'd capture well. It's a low hum at a single note. It starts at like 75 and you can hear it up to about 90, but I have never taken the tub any faster than that really. The hum doesn't warble or change, it just gets louder as speed increases until about 85, then it starts to quiet down somewhat. The guy at the shop said he thought it was the tires because of the speeds that it shows up at.
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Sep 24, 2017 18:20
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