McLaren 720 with rattling exhaust - £5k replacement cost!

[jim.mitch]

Evening all,

I have a 2018 720S with around 4k on the clock and it has a metalic rattling sound coming from the exhaust. It's apparent on idle, but not so much at higher revs. McLaren have told me it needs a new exaust back box at a cost of £5k plus fitting. Apparently the baffles have collapsed. I'm a bit shocked that a modern car's exhaust could fall to bits so quickly, especially when it's low mileage and spends most of its days dry in the garage!

Has anyone else had any similar issues, as after a few Google searches, I can't find anyone who has posted about this.

Does anyone know of anything else it could be? I thought it was just something lose!

Any advice very much apprecaited.

[andrew]

surely someone can cut open the silencers and weld the errant baffles ?
( vested interest as similar ongoing issue on my 911 )

[MrC986]

OP, if your car is out of warranty, I suggest you speak with someone like Thorney or Litchfield and see what replacement alternatives there are and what experiences they have of such an issue? - the high back pressure on the exhaust system may have in some way contributed to the issue and inevitably aftermarket replacement systems are cheaper and can often come in various sections so you can just replace the offending section rather than the whole system. You can guarantee that any warranty policy won’t cover an issue of this nature as well

[speedick]

There's been cases in the past of the cat disintegrating .... usually as a consequence of revving the engine hard whilst static to make a noise / flames (not aimed at the O.P. ..... just saying )

[DRZ]

Are you the first owner?

Early-ish 720Ss had a "party trick" where if you were particularly mechanically unsympathetic you could get them to throw flames out the exhaust. McLaren removed this quietly via a software update at some point as it was toasting cats and exhausts.

[CoolHands]

Second hand one £950. Not ideal but better than £5k

https://www.ebay.co.uk/itm/325186759951?hash=item4...

[Desert Dragon]

Hi Jim your car has only done 4000 miles in 5 years. Call up Mcl customer service and let them know you're not happy and would like a goodwill contribution towards the work. Your exhaust shouldn't fail after 5 years unless you've been leaving the car out to the elements which I somehow doubt. Sounds mollycoddled and should be perfect after only 4k miles especially if you've had car from new so can vouch for its use over last 5 years. If you bought when they were cheap used I can then understand Mcl reluctance but if you've had from new I'd be walking out with a new exhaust FOC from Mcl dealer. DD

[jim.mitch]

Thanks for the replies everyone, very helpful indeed!

I'm certainly going to try contacting McLaren as the fault has actually been present for over a year. I had meant to have it repaired on it's last service, but they'd already loaded it up to come back to me before quoting for the new backbox. Luckily I have corespondence from the dealer to show the fault was already present.

Wish me luck!

Thanks again.

[The Surveyor]

It’s possible that the baffles have corroded due to internal rusting caused by condensation in the exhaust, especially if your 4,000 miles over 5 years has been made up of lots of short trips when the car never gets properly warm.

If something has broken in the baffles it’s a McLaren good-will gesture, if it’s due to corrosion then it’s possibly due to the way it’s been used and it’s time to visit Larini IMHO.

[MDL111]

I once had a replacement back box fail within 18 months of it having been replaced (not a McLaren). I was not happy but the dealer refused to accept that this should not happen (said only 12 months warranty on parts, which I think was circumventing the legal obligation to warranty parts for 24 months - they didn’t care and in the end I just paid for it again).
I feel for you - rather annoying

[dng992]

jim.mitch said:

Evening all,

I have a 2018 720S with around 4k on the clock and it has a metalic rattling sound coming from the exhaust. It's apparent on idle, but not so much at higher revs. McLaren have told me it needs a new exaust back box at a cost of £5k plus fitting. Apparently the baffles have collapsed. I'm a bit shocked that a modern car's exhaust could fall to bits so quickly, especially when it's low mileage and spends most of its days dry in the garage!

Has anyone else had any similar issues, as after a few Google searches, I can't find anyone who has posted about this.

Does anyone know of anything else it could be? I thought it was just something lose!

Any advice very much apprecaited.

did you get a fix for this? was it covered under the official warranty or what?

[jim.mitch]

They wouldn’t cover it under warranty, but I did manage to get a few quid off the cost of the replacement exhaust. Still not great by any means, but better than nothing I guess!

[T70RPM]

Hi
I had this rattling on my new GT, and was asked by my knowledgable tech guy at the dealership, 'have you turned the aircon off?'
He was right. I had. The car has a definite rattle and vibration at idle with the climate control off. It's a proper metallic noise and noticable resonance. Even does it as you increase the RPM. As soon as I turned the aircon back on, it stopped.
Just thought I'd mention it before you got your wallet out......

[jim.mitch]

How bizarre!

Thank you, but it's had its repair carried out now and is heading back to me tomorrow. I will now be switching the A/C on and off out of interest though

[KevF]

I had a annoying rattle/vibration which occured between 2000 - 3000 rpm. turned out to be a loose exhaust mount.

Luckily local garage found it rather than a McLaren dealer.

[jim.mitch]

That's what I was more worried about. It always just sounded like something that was lose, rather than a faulty part. I guess I'll never know now.

[mk1coopers]

Worth asking for the old part back, list it for sale with what you think is wrong with it, might bring a few £££ in to offset the invoice, even if someone only wants it for wall art

[CoolHands]

It’ll be appearing on eBay soon no doubt

[Slow_GT]

T70RPM said:

Hi
I had this rattling on my new GT, and was asked by my knowledgable tech guy at the dealership, 'have you turned the aircon off?'
He was right. I had. The car has a definite rattle and vibration at idle with the climate control off. It's a proper metallic noise and noticable resonance. Even does it as you increase the RPM. As soon as I turned the aircon back on, it stopped.
Just thought I'd mention it before you got your wallet out......

Good Morning,
Just picked up a 2021 GT, and it appears I have the same rattle as you do. I hear it only at idle with the AC off. Once the AC turns on the rattle is gone. Did you ever have this checked or repaired?

[jim.mitch]

McLaren completly replaced the exhaust, as they said it couldn't be repaired. I hope you have more luck with yours. McLaren will always find something to bill you for in my experience.