Help diagnose 'clink' sound? video link

Russianblue · #1 08-25-2018, 01:01 PM

This sound happens when I put the car in reverse and also when accelerating normally, then let off gas (clink), the reapply the gas (clink). I can't tell if it is the front diff, transfer case or tranny.

https://youtu.be/CDn1Yk3BOsI

I am able to reproduce it while parked, as in the video, while shifting from park to reverse and back with my foot on the brake. Sounds exactly the same as it does when I'm driving. No slippage of any sort and everything seems to be working perfectly other than the noise.

It is possible my front diff is low on fluid. Could that be causing it? My other "best guess" was slack in the transfer case chain.

OR, it is just the transmission warming up for her death song? I hope not. I'd hoped to bequeath this to my kid this fall when she gets her license.

Thanks!

2003 e53 X5 with 177k. Original (lifetime) tranny fluid...never changed since new.

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andrewwynn · #2 08-25-2018, 01:23 PM

Sounds like fairly normal drive train slack. There is a little more "ping" from some metal resonating. I would look into typical wear parts like the guibo and the CV half axles as well as the rear bushings. My first thought is maybe the front driveshaft is vibrating when the slack comes out. Think of it like water hammer in a pipe: when you switch from forward to reverse the transmission output shaft might turn a quarter turn before all the slack is out of the system so It hammers pretty good.

Russianblue · #3 08-25-2018, 01:40 PM

okay then. that doesn't sound so bad. the problem is that it didn't used to do that, but it IS an old car after all ; )

I'll check the guibo and do a general inspection once I get the Valve cover gasket and OFH gaskets changed and I can see the engine again beneath the ever present oil slick, lol!

andrewwynn · #4 08-25-2018, 01:45 PM

It probably was doing to some degree. I never heard my drive train clink until I had my rear seat off and was doing work on my fuel pump. It's 10x as audible.

I recommend driving near a solid wall occasionally with the windows down and the radio and HVAC off. Go from fwd to reverse and opposite learn the normal sounds to determine when something unusual happens.

Once I discovered rust had fallen between my rock guard and rear rotor made a strange continuous scratchy sound

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wpoll · #5 08-25-2018, 04:04 PM

I was going to suggest the cv joint at the front of the rear diff - they get dry and the ball bearings move a lot when the load changes direction. I've seen that issue on an e39 touring but it sounded much more like marbles in a tin can than your single clink sound.

Some folk have managed to lube the cv without removing it...

Russianblue · #6 08-27-2018, 10:46 AM

one thing that doesn't make much sense to me is that when it is cool outside first thing in this morning, this sound is much less prominent, if not inaudible. once the weather and the car heat up, it gets louder and more pronounced.

andrewwynn · #7 08-27-2018, 12:03 PM

That's logical. Thicker oil in the drive train will slow the progress of the slack chain.

If you look under the car when somebody else changes gears, you can watch how much the output of the transmission moves with the car not moving.

I get a very distinct "clink" changing fwd to reverse etc but don't get the "ping".

I would try to locate the exact source of the ping in case it's more serious. I would guess a "sound short" through a worn bushing or similarly a worn giubo (joo-boh*) (flex disk on the front of the front driveshaft)

*giubo is an abbreviated form of GIUnto BOschi. Giunto meaning "joint" in Italian and Boschi is the inventor.

Back to the issue: if the rear diff is low on oil it could cause a ping (ring from vibrating large gear) so definitely find the source of the sound.

Russianblue · #8 08-27-2018, 12:42 PM

awesome tips. thanks so much!

I put a heavy duty M5 guibo on my old non-M5 e28 turbo. not too terrible a job. Made a world of difference it the drivetrain feel though.

I plan to do my valve cover, vanos seals and OFH gaskets this weekend. I will see if i can find some time to take a look at the diff fluid levels.

i just gotta get this thing road-worthy (not dealing with all the hiccups I don't mind dealing with) by the time by kid gets her license in late October. I can't have her leaking oil all over OTHER people's driveways, lol!

If I fix all that stuff though, I'm not gonna want to give it to her (and pick up a $500+ a month car note to boot).

I really need to review that thread about the permanent tail light fix with the extra ground wires.

andrej1979 · #9 09-13-2018, 12:52 AM

Did you manage to fix it.

Russianblue · #10 09-29-2018, 06:47 PM

just wanted to circle back with you guys after figuring this out. I took it to one of the only indies in town that I trust because I just needed it done and was getting them to change the oil pan gasket anyway. When I went in, I just mentioned it to them to get some feedback. They stopped me halfway through the description and said..."POSITIVE it's the front drive shaft splines starting to go". So they have a source for the front driveshafts with the extended spline. They put it in and that was it. clink gone. totally and completely!

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