BONK/CLUNK NOISE VF SV6 automatic 2016

[Jasonjohn]

Understandably, I get the stress. Having gone to multiple mechanics, if no one is giving you an answer, you can either keep going to other mechanics, sell it, or start digging into it.

Im of the view that when you get to that point its time to start diagnosing and going through a process of elimination.

Here's how I would be looking at it before loading the parts cannon or going to another mechanic

The issues are

20-60km, you get a clunking -

Id be thinking something mount/balance related

Are the wheels all balance?
Are all the wheels not buckled?
Is the tail shaft bearing stuffed?
Are the tail shaft couplings stuffed?
Are all the bolts in the drive line tightened?
Are the mounts (Trans mount, tail shaft bearing mount) tightened?
Diff mount bushings, are they buggered?

Gurgling sound

That to me flags something related to fluid, and gurgling means id be looking to the gearbox

Is something going on with the torque converter?
Is something going on with the fluid pump in the trans?
Are all the fluids at the correct level?
Unlikely, but worth checking the diff fluid too?

Clunking noise going to reverse

Right, something is likely loose

There is a Service Bulletin that describes this exact issue (seemingly)
I have attached the bulletin. Read it back to back, start considering it

In addition

There is movement in the diff, and you said you had it replaced.

Was it a brand new replacement?
If it was second hand, what was the condition?
Are the mounts stuffed?
Are the tail shaft couplings stuffed?
Could the drive axles themselves be stuffed?
If I disconnect the tailshaft, and rotate the wheels or rotate the diff back and forth, can I feel a clunk?
If I disconnect the tail shaft, and rotate the wheels or rotate the diff back and forth, does everything rotate smoothly?
If I put the gearbox into neutral and go underneath it, can I rotate the drive shaft by hand and does it feel smooth?

This is a long list, but it's going to give you some things to start considering and beginning your process of elimination. There is many more knowledgeable people on this forum who hopefully will add some things in too.

You've got a transmission, tail shaft, diff, and axles. Bearings and bushings mounting the various bits and bobs. Need to start at one end and work your way back.

An early investment in a 3 tonne Repco MechPro low profile jack and 4 axle stands has payed itself off many times over for me fixing and upgrading my car

There is a complete factory service manual on here. Search for it, download it and start reading. I have learnt so much from when I got my car to now just by literally sitting down and reading/studying that manual

Hopefully this gives you some pointers!

This is the noise I’m getting while driving - note - in the video I’m purposely letting go of the throttle quickly to amplify the noise of this clunk. Video below

 

[VT2Commie]

This noise is a metallic donk noise for sure coming from the transmission output flange spline free play.

"Glueing" the transmission flange with adheasive (Loctite 272) as outlined in the TSB @NJD-1992 and @Skylarking have pointed out in their above posts will confidently fix your issue.

 

[Jasonjohn]

This noise is a metallic donk noise for sure coming from the transmission output flange spline free play.

"Glueing" the transmission flange with adheasive (Loctite 272) as outlined in the TSB @NJD-1992 and @Skylarking have pointed out in their above posts will confidently fix your issue.

What would happen if the issue didn’t get fixed ? ( I want it fixed but am short of money at the moment )

 

[VT2Commie]

What would happen if not fixed?
You would have an irritating noise you don't want.
Worst case senario, the transmission output flange maybe working loose the output flange nut with the back and forth movement in the splines of the transmission output shaft, ( high chance it's not as the nut is staked or peined) and your driveshaft comes loose from the transmission, but I've seen stranger things.

NVH diagnosis is a process of elimination. A good workshop would use an acoustic "ears" tool to pinpoint the exact source of the noise. Wait until you get the funds and put up with noise?

It sounds like you have two issues IMO.

The metallic donk fix requires no extra cost of parts other than transmission pinion flange nut, driveshaft bolts (rear) and torque prevailing front driveshaft coupling nuts, if the mechanic does it properly by the book.

The gurgling noise maybe a transmission/torque converter issue, (couldn't say as have not heard anything in the video sounding like gurgling).

If you wanted a "cheap fix" and no parts replaced( highly not recommended) they wouldn't replace the single use parts.

Personally I'd replace the single use bolts and nuts for the drive shaft as being a high velosity moving part when operating, I wouldn't want it coming loose.

 

[Jasonjohn]

What would happen if not fixed?
You would have an irritating noise you don't want.
Worst case senario, the transmission output flange maybe working loose the output flange nut with the back and forth movement in the splines of the transmission output shaft, ( high chance it's not as the nut is staked or peined) and your driveshaft comes loose from the transmission, but I've seen stranger things.

NVH diagnosis is a process of elimination. A good workshop would use an acoustic "ears" tool to pinpoint the exact source of the noise. Wait until you get the funds and put up with noise?

It sounds like you have two issues IMO.

The metallic donk fix requires no extra cost of parts other than transmission pinion flange nut, driveshaft bolts (rear) and torque prevailing front driveshaft coupling nuts, if the mechanic does it properly by the book.

The gurgling noise maybe a transmission/torque converter issue, (couldn't say as have not heard anything in the video sounding like gurgling).

If you wanted a "cheap fix" and no parts replaced( highly not recommended) they wouldn't replace the single use parts.

Personally I'd replace the single use bolts and nuts for the drive shaft as being a high velosity moving part when operating, I wouldn't want it coming loose.

Best response I have had

What would happen if not fixed?
You would have an irritating noise you don't want.
Worst case senario, the transmission output flange maybe working loose the output flange nut with the back and forth movement in the splines of the transmission output shaft, ( high chance it's not as the nut is staked or peined) and your driveshaft comes loose from the transmission, but I've seen stranger things.

NVH diagnosis is a process of elimination. A good workshop would use an acoustic "ears" tool to pinpoint the exact source of the noise. Wait until you get the funds and put up with noise?

It sounds like you have two issues IMO.

The metallic donk fix requires no extra cost of parts other than transmission pinion flange nut, driveshaft bolts (rear) and torque prevailing front driveshaft coupling nuts, if the mechanic does it properly by the book.

The gurgling noise maybe a transmission/torque converter issue, (couldn't say as have not heard anything in the video sounding like gurgling).

If you wanted a "cheap fix" and no parts replaced( highly not recommended) they wouldn't replace the single use parts.

Personally I'd replace the single use bolts and nuts for the drive shaft as being a high velosity moving part when operating, I wouldn't want it coming loose.

Best reply I’ve had. Appreciate it. I have a video of going from reverse to drive you’ll hear the clunk, but when going from drive to reverse you’ll hear that gurgle sound. That’s what I’m hearing while driving at low speeds and it gets harder to listen at high speeds

 

[Jasonjohn]

What would happen if not fixed?
You would have an irritating noise you don't want.
Worst case senario, the transmission output flange maybe working loose the output flange nut with the back and forth movement in the splines of the transmission output shaft, ( high chance it's not as the nut is staked or peined) and your driveshaft comes loose from the transmission, but I've seen stranger things.

NVH diagnosis is a process of elimination. A good workshop would use an acoustic "ears" tool to pinpoint the exact source of the noise. Wait until you get the funds and put up with noise?

It sounds like you have two issues IMO.

The metallic donk fix requires no extra cost of parts other than transmission pinion flange nut, driveshaft bolts (rear) and torque prevailing front driveshaft coupling nuts, if the mechanic does it properly by the book.

The gurgling noise maybe a transmission/torque converter issue, (couldn't say as have not heard anything in the video sounding like gurgling).

If you wanted a "cheap fix" and no parts replaced( highly not recommended) they wouldn't replace the single use parts.

Personally I'd replace the single use bolts and nuts for the drive shaft as being a high velosity moving part when operating, I wouldn't want it coming loose.

So the transmission doesn’t need to come out for this type of work to be done?

 

[VT2Commie]

So the transmission doesn’t need to come out for this type of work to be done?

For the metallic donk noise, No.

If this gurgling noise is diagnosed by a good mechanic they would check the transmission fluid level and if low top it up with Dexron6 or equivalent compatible fluid. If just low fluid, No.

Then if this "gurgling" noise is still there after a fluid level check and correction then possibly, Yes.

 

[Jasonjohn]

For the metallic donk noise, No.

If this gurgling noise is diagnosed by a good mechanic they would check the transmission fluid level and if low top it up with Dexron6 or equivalent compatible fluid. If just low fluid, No.

Then if this "gurgling" noise is still there after a fluid level check and correction then possibly, Yes.

Fluid is apparently ok but I’ve never changed the trans fluid at 162000 right now..

 

[Skylarking]

Fluid is apparently ok but I’ve never changed the trans fluid at 162000 right now..

The factory normal scheduled trans fluid change is @ 150,000km unless it’s under the severe service schedule (= city stop start city driving in summer, towing, etc) in which case fluid is changed @ 75,000km
Many forum members feel that trans fluid should be changed every 50,000kms

So your trans fluid change is late by either 12,000km if normal driving or by 87,000km if stop/start city driving/towing but some forum members would say the car should have had 3 trans fluid changes by now. Fluid level may be ok but the fluid will be shite

Maybe just get the trans fluid flushed and the filter changed sooner rather than later while having the condition of the old fluid, old filter and the bottom of the pan checked

 

[losh1971]

As above get that trans serviced in the next couple of weeks. That's way too long to not have been serviced. The factory 150k is a joke. Holden didn't care if the trans died as it would be out of warranty when it did. So they put 150k oil change because they can get away with it.