V6 Tourer cabin noise

FrattonEnder · 6th March 2024, 11:49

Looking for a few pointers on the possible cause of the booming I've started to get in the cabin of my V6 ZT-T.

Bought the car back at the end of last November and I was getting a 'resonant drone' at certain speeds (40-60) and on certain road surfaces. I put this down to the cheap budget tyres the previous owner had fitted. This drone hadn't really got any worse and I was going to swap the wheels from my ZT just to prove or reject my theory it was just rubbish tyres.

However, over the weekend, the drone has got worse and there's a definite vibration coming through the pedal box area. It's starting at around 25mph and on pretty much any surface. This is coupled with a bad judder in slow traffic. It's that loud I struggled to hear the stereo in the drive back up the M5 from Bristol on Monday!

I've taken a look at the lower engine mount and that's been swapped out for a set of Powerflex bushes. I'm not going to totally discount that as one of the issues (I have a brand new DMGRS one ready to fit). Engine doesn't seem to rock excessively on tick over or when I blip the throttle. Based on the info I got from the previous owner, the car's had new wheel bearings all round, top mounts, shocks and springs, so that should all be fine. Gut feel is the top engine and gearbox mounts, together with maybe duff wheel bearings. The car does have a stainless sports exhaust fitted, but driving with the window down, it doesn't sound that bad.

Hoping to have a poke around this weekend or next (weather dependant) so any pointers would be greatfully received.

FrattonEnder · 8th March 2024, 15:36

Current prognosis is wheel bearing failure, but with no ABS or speedo issues. The car had new bearings all round only last year, so I've contacted the seller and they've agreed to get them changes under warranty - fortunately they're a trader so they've only go to worry about the cost of the bearings.
Hopefully I'll have it all sorted in time for the National at Gaydon!

Mike Noc · 9th March 2024, 08:26

Have you checked the driveshafts and the support bearing on the offside?

FrattonEnder · 11th March 2024, 10:55

Quote:

Originally Posted by Mike Noc

Have you checked the driveshafts and the support bearing on the offside?

Thanks Mike. I'm going to have a crawl about underneath next weekend and see what I find. Either way, she's going back to the previous to get fixed, seeing as he chucked aload of new parts at her before selling.

FrattonEnder · 18th March 2024, 09:31

Well, after having a good old crawl about underneath the car this weekend, I've found that there's quite a bit of play in both driveshafts along with a 'grumble' from the hubs, certainly compared with my diesel ZT where there's none. Must be a good 5mm movement in and out - enough to give a clonk when the shaft hits the end of its travel.
Am I safe in assuming there shouldn't be any, or negligable, play in the shafts?
I'm going back to the dealer when they're back of their holidays later this week, so want to be armed with some detail.

6th March 2024, 11:49	#1
FrattonEnder Avid contributor MG ZT Join Date: May 2020 Location: Gloucester Posts: 233 Thanks: 40 Thanked 47 Times in 28 Posts	V6 Tourer cabin noise Looking for a few pointers on the possible cause of the booming I've started to get in the cabin of my V6 ZT-T. Bought the car back at the end of last November and I was getting a 'resonant drone' at certain speeds (40-60) and on certain road surfaces. I put this down to the cheap budget tyres the previous owner had fitted. This drone hadn't really got any worse and I was going to swap the wheels from my ZT just to prove or reject my theory it was just rubbish tyres. However, over the weekend, the drone has got worse and there's a definite vibration coming through the pedal box area. It's starting at around 25mph and on pretty much any surface. This is coupled with a bad judder in slow traffic. It's that loud I struggled to hear the stereo in the drive back up the M5 from Bristol on Monday! I've taken a look at the lower engine mount and that's been swapped out for a set of Powerflex bushes. I'm not going to totally discount that as one of the issues (I have a brand new DMGRS one ready to fit). Engine doesn't seem to rock excessively on tick over or when I blip the throttle. Based on the info I got from the previous owner, the car's had new wheel bearings all round, top mounts, shocks and springs, so that should all be fine. Gut feel is the top engine and gearbox mounts, together with maybe duff wheel bearings. The car does have a stainless sports exhaust fitted, but driving with the window down, it doesn't sound that bad. Hoping to have a poke around this weekend or next (weather dependant) so any pointers would be greatfully received. __________________ Serial Longbridge owner - Rover 213SE, Rover 216GTi, Rover 416 SLi, MG ZS 120+, MG ZT CDTi, MG ZT-T 190. Flies in the ointment - Ford Mondeo Mk4 CDTi Zetec, MINI Cooper 1.6

8th March 2024, 15:36	#2
FrattonEnder Avid contributor MG ZT Join Date: May 2020 Location: Gloucester Posts: 233 Thanks: 40 Thanked 47 Times in 28 Posts	Current prognosis is wheel bearing failure, but with no ABS or speedo issues. The car had new bearings all round only last year, so I've contacted the seller and they've agreed to get them changes under warranty - fortunately they're a trader so they've only go to worry about the cost of the bearings. Hopefully I'll have it all sorted in time for the National at Gaydon! __________________ Serial Longbridge owner - Rover 213SE, Rover 216GTi, Rover 416 SLi, MG ZS 120+, MG ZT CDTi, MG ZT-T 190. Flies in the ointment - Ford Mondeo Mk4 CDTi Zetec, MINI Cooper 1.6

18th March 2024, 09:31	#5
FrattonEnder Avid contributor MG ZT Join Date: May 2020 Location: Gloucester Posts: 233 Thanks: 40 Thanked 47 Times in 28 Posts	Well, after having a good old crawl about underneath the car this weekend, I've found that there's quite a bit of play in both driveshafts along with a 'grumble' from the hubs, certainly compared with my diesel ZT where there's none. Must be a good 5mm movement in and out - enough to give a clonk when the shaft hits the end of its travel. Am I safe in assuming there shouldn't be any, or negligable, play in the shafts? I'm going back to the dealer when they're back of their holidays later this week, so want to be armed with some detail. __________________ Serial Longbridge owner - Rover 213SE, Rover 216GTi, Rover 416 SLi, MG ZS 120+, MG ZT CDTi, MG ZT-T 190. Flies in the ointment - Ford Mondeo Mk4 CDTi Zetec, MINI Cooper 1.6

9th March 2024, 08:26	#3
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Have you checked the driveshafts and the support bearing on the offside?