Stocker

I've only noticed this today, and already I hate it.



My car is making a noise that

• Sounds kinda like an exhaust leak, a quiet repetitive tick/click. Sounds kinda like a diesel truck running alongside the car, but quiet. Turn up the radio and you'd miss it. Drive on a highway that makes the tires sing and it can't be heard
  
• comes during on-throttle operation. Not when coasting/decelerating. My friend made it sound when downshifting some strange way but I wasn't paying attention sorry
  
• Can't hear it when the car isn't moving. idle sounds normal, revving sounds normal.
  
• Is dependent on vehicle speed, not engine speed, but the quality of the noise changes with different gears in use
  
• Doesn't get worse when turning either direction (checked in a parking lot next to a building)
  
• Is hard to localize. From the front, sounded like driver side to me, my friend couldn't really tell which side
  
• Can be heard *better* in the cabin with windows up
  

Notably:

• The car has 212k miles on it
  
• Only one wheel bearing *ever* had to be replaced, front passenger
  
• She runs (as my friend who drove it to listen said) "surprisingly strong for how it looks"
  
• Axles are old-ish, would have to check the maint. log book to see how old. I know there is at least one split boot
  
• Exhaust manifold was replaced once with the newer (with slits between runners) style by Hyundai ages ago
  
• Plugs and wires are pretty recent, oil is due for a change, but it has oil which didn't look too bad on the dipstick
  
• Gear oil was recently changed (Redline, again) and the drained oil looked normal.
  
• The driver/front wheel doesn't rock top/bottom when the car is jacked up - but the one bad wheel bearing didn't either, because it was trying to seize up solid (didn't jack/wiggle check passenger side yet)
  
• With the driver's front wheel jacked up the tire has a noise when rotated by hand that is probably brakes rubbing
  

Suspects:

• wheel bearing
  
• axle
  
• brake pads (doubtful)
  
• final drive gear or output shaft
  

If the car doesn't explode and it doesn't get drastically worse, this will be looked-at this weekend or sooner, time allowing. Please shoot me any suggestions and/or ideas you may have.



updated with slightly better comments from this morning's drive.

Mr. Muffin

Timing belt or lash adjuster maybe? My tiburon just started same thing a couple weeks back...



I'm at 99k got the timing belt, need to put it in before snow hits.. If it still ticks its gonna encourage me to clean the lash adjusters and do the exhaust cam swap lol

187sks

Hmm, I know it's speed dependent but the load on the engine changes in different gears as well.



Very different areas but CV joint and timing belt idler pulley are my two initial thoughts.



If you or a buddy have a GoPro put it in a few locations under the hood and see if you can find a place where it's noticeably louder.

tibbytib

My bets are on CV joint.



Just reread your initial post. You said you have a split boot on an axle. I'd say that should be your number one lead to follow. Doesn't take long for dirt to get in there and Jack up those splines.



So, my bet still stands.

Stocker

I made some cell phone videos but they had potato quality audio so i deleted em. I'll try again to get a decent recording.



I can definitely hear my noise on part throttle, especially uphill. I can also just barely hear it coasting. Full engine load or engine speed over 4KRPM are too loud to hear the noise.



I spent some quality time with the car and I think it's either my standards are too low for axles, or the axles are bad, or it's something surprising and expensive.



No DTCs or long term data stored in the computer, according to my OBD2 handheld scanner



I drained out 800ml of gear oil into a clear beaker and happily it did NOT look like aluminum paint. Transaxle oil is clear and the appropriate funky pink color for Redline. I ran a magnet through it and didn't pick up anything. There were a few ~1mm black flecks in the bottom of the beaker but they could have come from the car, which is dirty underneath, or maybe from not cleaning the beaker first (oops).



With the brake calipers pushed loose enough to let the wheels turn, but still dragging a little, both front wheels rotate smooth and easy as each other, and no roughness can be felt, even through a hand resting on the spring. No rocking/play was felt. Back wheels rorate smoothly also. I'm thinking the wheel bearings are probably good.



There is a circumferential cracking around the passenger side inner axle boot, but all the boots are intact, with no grease spray.



The axles are about as tight as each other. With the wheel removed, there is ever so little play in the joints, maybe a couple of degrees slack in rotation with a small clunk when changing by hand between forward and reverse rotation of the axle (by turning the brake rotor by manually). The drivers axle stays tight into the gearbox, the passenger side has maybe 2-4mm of slip in and out, but clinks against a hard stop, still retained by the c-clip. If there's supposed to be absolutely ZERO play then the axles are F'd. If a little bit of "I'm pretty sure it moved a tiny bit" motion is okay, the axles are okay.



The spark plug wire cover was smashing one wire, and I'll replace that one and see if it makes a difference but though I hope so, I am not holding my breath about it.



The gear ratios are close enough, and my intake loud enough, it's hard to be 100% sure it's road speed related, not engine speed. This would be easier to analyze if I weren't also driving at the same time. A good video would really help

Stocker

A few points to add



I had my son ride along and it seems to him like the noise is definitely road-speed and not engine-speed related. Videos from another phone are only slightly less-potato-quality audio; this is really a faint noise and my car is ... not quiet.

The noise is definitely heard decelerating down hills, sometimes as loud as when on throttle up hills

Noise changes slightly but doesn't go away when brakes are applied and throttle is added to maintain speed

The smooshed spark plug wire change didn't fix anything.

For grins because I had the wheels off checking axles, I swapped front tires from side to side with no change in the noise

The noise isn't getting worse fast. If you see photos of my car on a wrecker with a thrown rod or exploded gearbox, maybe it will announce itself. Until it does, I'll keep driving the car - but less like a stolen car than usual!



Thinking about it, a cracked boot on a CV joint could be as bad as a torn boot - a cracked boot on a hot joint driven through a puddle is going to draw in water and make for a bad time in the joint after a while. I need to get back under there and *really* examine the joints, and see if there is any other sign of badness I didn't note on my quick check the other day. I really want this to be an axle problem because they are sooo much less hassle than a transaxle replacement job - but this transaxle has 240,000-ish miles on it, which is pretty good service no matter how you look at it!

Stocker

The transmission gear oil which was clear and pink this weekend, is now not clear and much closer to gray.



So . . . who wants to come play cars on my driveway? Bring a spare transaxle with you, willya?



I had some difficulty with an axleshaft going in/out of the gearbox tonight. I'm pretty sure I killed the oil seal because I found a little seal tension spring inside the gearbox when I went to plug the axle back in. Or else that was the spring that holds the grinding noise in. Either way, this gearbox is on its way out. Now on to my second-least favorite task: finding and replacing a transaxle.

2000J25SP

Get an 03-08 Tiburon transmission with the 4.05 fd. It made my J2 a bit more fun to drive, especially after 300 lbs of weight reduction + ihe + 240 duration cams.

Stocker

I already "only" get like 27-28MPG, so a shorter gear wouldn't really be something I'd go hunting for. If top hear is long enough, I wouldn't mind a shorter final drive, but i don't really want to LOSE MPG.



That's a question I was going to ask anyway - what else will I need? Up to a 2001 Tiburon obviously is all the same parts as I already have, but at what model year do I need to start getting the shifter and cables from the donor? Do any of the transaxle mounts change enough I need them from the parts car?

i8acobra

Sorry I missed this. I'm pretty sure I know what it is based on your first post. It's one of the support bearings on the differential (most likely the ring gear end) or the output shaft.