Grumbling Noise - What's Causing It?? TRANSMISSION

[StudioWizard]

Aha!! No, that's not the grumbling noise I was referring to, but it is another noise I've been asking my mechanic about. He said THAT sound might be belts or a tensioner, etc.

The grumbling noise is a low-frequency sound and vibration - almost like the muffler is loose or something. The car shakes slightly - usually between 4th and 5th gears when I'm driving slowly and worse uphill.

Have you had to fix a torque converter before? Do you think a bad TQ can cause both that clicking sound and the low frequency rumble/grumble sound/vibration, too?

 

[Matty_Z4]

Aha!! No, that's not the grumbling noise I was referring to, but it is another noise I've been asking my mechanic about. He said THAT sound might be belts or a tensioner, etc.

The grumbling noise is a low-frequency sound and vibration - almost like the muffler is loose or something. The car shakes slightly - usually between 4th and 5th gears when I'm driving slowly and worse uphill.

Have you had to fix a torque converter before? Do you think a bad TQ can cause both that clicking sound and the low frequency rumble/grumble sound/vibration, too?

Not 100% sure but in the videos above that is my car and it was fixed by installing a remanufactured TQ. It presented itself as that rattling sound and the car needed quite a few revs for it to start to take off, you had to drive the car like you mean it.

If you have the above noise and its not the cats, broken honeycomb can sound similar and they are in the downpipes of the engines. Or a belt/pulley then it could be the torque converter.

The noise at 42 - 50 mph does it go away if you put the transmission in nurtural and coast for a bit? When safe to do so.

 

[StudioWizard]

The noise at 42 - 50 mph does it go away if you put the transmission in nurtural and coast for a bit? When safe to do so.

Yes, it goes away in all cases in neutral. Also, it's less likely to have that low vibration if I'm pushing the car and revving higher. It worst when I'm driving slowly and barely accelerating. As the car gets to around 38-42 mph and switches to 5th, it grumbles/vibrates. If accelerate quickly, there's little or no issue switching from 4th-5th. Also, if I use steptronic, there's almost no issue that I can tell.

It'd be great to knock out both the clicking sound AND the low grumbling sound with one fix.

Should I go to a transmission specialist? I mean... are "regular" mechanics generally not totally qualified to diagnose/fix this? A buddy of mine told me this (he has a 1980 Mercedes).

 

[StudioWizard]

The noise at 42 - 50 mph does it go away if you put the transmission in nurtural and coast for a bit? When safe to do so.

Yes, both the clicking sound and low vibration go away in all cases in neutral. Also, it's less likely to have that low vibration if I'm pushing the car and revving higher. It worst when I'm driving slowly and barely accelerating. As the car gets to around 38-42 mph and switches to 5th, it grumbles/vibrates. If accelerate quickly, there's little or no issue switching from 4th-5th. Also, if I use steptronic, there's almost no issue that I can tell.

It'd be great to knock out both the clicking sound AND the low grumbling sound with one fix.

Should I go to a transmission specialist? I mean... are "regular" mechanics generally not totally qualified to diagnose/fix this? A buddy of mine told me this (he has a 1980 Mercedes).

 

[deltasierra]

You do need to go to a ZF specialist he will connect his scanner and tell you what’s wrong, 160k is a lot of miles. When you changed the oil in the trans did you change the sump which has the filter built in, it may not have been done since new.
If you do get into stripping the auto box expect a bill for £2k.

 

[Matty_Z4]

Should I go to a transmission specialist? I mean... are "regular" mechanics generally not totally qualified to diagnose/fix this? A buddy of mine told me this (he has a 1980 Mercedes).

If you have the option to take it to a BMW specialist that knows the cars then that would be better than just a regular generalist mechanic. Not sure how things are in the states so you may need to find a Euro car specialist rather than a specific BMW guy.

The BMW Specialist I take mine to (He does all the big work and I do the tinkering) has been working on these cars for 30+ years so knows most of the annoying gotchas so can pretty much diagnose things by intuition. He also happens to be ZF trained for transmission servicing although he does not get involved in rebuilds.

If it does turn out to be the torque converter it can be quite expensive I have just looked up the bill from when I had mine sorted and it worked out like this.

£42.09 Flex Plate
£426.14 Torque Converter
£40 Transmission fluid
+ 5 Hours Labour
+ 20% VAT

This was in 2019 so a couple of years ago and in UK £££ so prices may vary but at least you know a ball park if it does turn out to be the TC.

It was suggested that my problem was caused by a previous owner doing two foot launches, Holding the brake and the gas until the limiter kicks in then letting off the brake.