MPE has developed a low buzzing/rattling

[jmg]

I've recently noticed that my MPE has started to develop a low RPM buzzing/rattling in Sport and Sport+ mode. It's only from a dig at low acceleration. If I gas it, there is no buzzing/rattling. The best I can describe the sound is that it is very loud, it has a lot of bass, and it sounds like the whole cat is vibrating against metal. Almost like a tuba. The MPE came installed on the car and I've had it for a little over a year.


It kinda sounds like hitting a Bb on the tuba, with a little more metal on metal sound. No I don't play tuba, I just youtubed it:

If you are on mobile, the sound is at 1:19.

I remember hearing about the welds and seams coming apart on some MPEs, but I can't find the thread. Maybe that is my issue. Maybe it's normal?

[tom @ eas]

Carbon tips? We've seen a few instances in which they rattle at a certain RPM and were replaced under warranty.

[badbimmer]

Originally Posted by jmg

I've recently noticed that my MPE has started to develop a low RPM buzzing/rattling in Sport and Sport+ mode. It's only from a dig at low acceleration. If I gas it, there is no buzzing/rattling. The best I can describe the sound is that it is very loud, it has a lot of bass, and it sounds like the whole cat is vibrating against metal. Almost like a tuba. The MPE came installed on the car and I've had it for a little over a year.


It kinda sounds like hitting a Bb on the tuba, with a little more metal on metal sound. No I don't play tuba, I just youtubed it:

If you are on mobile, the sound is at 1:19.

I remember hearing about the welds and seams coming apart on some MPEs, but I can't find the thread. Maybe that is my issue. Maybe it's normal?

Did you jack it up and take a look? Certainly doesnt sound normal for a high performance luxury vehicle.

[jmg]

Originally Posted by badbimmer

Did you jack it up and take a look? Certainly doesnt sound normal for a high performance luxury vehicle.

No. I don't have a lift. I checked the seals on the sides of the cat, and there doesn't seem to be any cracks as far as I can tell.

Originally Posted by tom @ eas

Carbon tips? We've seen a few instances in which they rattle at a certain RPM and were replaced under warranty.

Yup CF tips. Looks like it's off to the dealer I go!


Additional note: I tried to duplicate it today at work. I couldn't really get it to do it again. It must be only when the car is warm. I'm going to film it next time to show my SA.

[mike@x-ph.com]

Originally Posted by jmg

No. I don't have a lift. I checked the seals on the sides of the cat, and there doesn't seem to be any cracks as far as I can tell.



Yup CF tips. Looks like it's off to the dealer I go!


Additional note: I tried to duplicate it today at work. I couldn't really get it to do it again. It must be only when the car is warm. I'm going to film it next time to show my SA.

Hopefully they will not give you a hard time before replacing them

[jmg]

Originally Posted by mike@x-ph.com

Hopefully they will not give you a hard time before replacing them

I wouldn't be surprised if they "couldn't replicate the problem". Is this a known issue?

[mike@x-ph.com]

Originally Posted by jmg

I wouldn't be surprised if they "couldn't replicate the problem". Is this a known issue?

I have heard about it, not sure how common it is

[horsepower_and_hounds]

Have them check for weld cracks while your in. My carbon tips have been fine, the can was cracked causing my buzzzzzzz'n

[Brasko]

Having a similar issue. Took it in to the service center to have it looked over. Explained the sound/concern and stated to them the muffler may be cracked or there may be a slight exhaust leak. They could not duplicate the issue and did not find any leaks or cracks throughout the exhaust.

I really don't think it's anything critical. More of an annoyance than anything. I think the screws holding the exhaust tips may need to be tightened or replaced. I only mention that because during cold start I've noticed a similar sound. If I touch/hold the exhaust tips the sound goes away.

For the record I have titanium tips on my MPE. Dealer installed the exhaust too.

There is another thread in the forums where a member had similar issues and replaced the hex screws holding the exhaust tips in place. I'll try to dig it up and share.


EDIT: Here is the link to the thread I mentioned.

http://f80.bimmerpost.com/forums/sho....php?t=1322289

[jmg]

I'm starting to suspect it's my license plate. I run with no frame and it now reminds me of when was young and didn't care about my hearing and used to have a huge sub in the back. The plate would rattle and make a similar noise. I'm going to take my plate off and test it out.

[Super Spartan]

Originally Posted by jmg

I'm starting to suspect it's my license plate. I run with no frame and it now reminds me of when was young and didn't care about my hearing and used to have a huge sub in the back. The plate would rattle and make a similar noise. I'm going to take my plate off and test it out.

I've heard that simply tightening the CF Exhaust tips properly would fix the issue. Can you have them try that?

[jmg]

Just got a call from my SA. MPE needs to be completely replaced! Turns out the valve is completely shot. It's currently backordered but should be coming from Germany in a little over a week. I'm glad i'm still under warranty!!!!

[damageprone]

I have a similar rattling sound usually at cold start as well. I couldn't find any cracks on the side as mentioned in various other threads at least. No carbon tips for me either. Hopefully it's not a valve issue. It would be a shame to have to replace the exhaust. It took me 13K miles to break it in and get it to sound like it should.

[Super Spartan]

Originally Posted by damageprone

I have a similar rattling sound usually at cold start as well. I couldn't find any cracks on the side as mentioned in various other threads at least. No carbon tips for me either. Hopefully it's not a valve issue. It would be a shame to have to replace the exhaust. It took me 13K miles to break it in and get it to sound like it should.

The exhaust needs 13K Miles to break it in??

[jmg]

Originally Posted by damageprone

I have a similar rattling sound usually at cold start as well. I couldn't find any cracks on the side as mentioned in various other threads at least. No carbon tips for me either. Hopefully it's not a valve issue. It would be a shame to have to replace the exhaust. It took me 13K miles to break it in and get it to sound like it should.

No visible exterior cracks on mine either. I don't even remember what the car sounded like new... I guess I will find out.

[mhjeep]

I had to have mine replaced under warranty recently for similar issue. Only had about 10k miles on it. Maybe less. No cracks in can. Just a horrible vibration. They tested the valves as these can "stick" apparently but that wasn't it either.

[damageprone]

Originally Posted by jmg

No visible exterior cracks on mine either. I don't even remember what the car sounded like new... I guess I will find out.

I went out to check again and it does appear that there may be cracks at both sides of my exhaust as others have reported. Looks like I'll have to call my SA.

[Pate68]

dont these mpe exhausts often break on the side of the muffler itself ?
would love the get one too.. but you read way too frequent about these cracks happening...
feelin sorry for you

[horsepower_and_hounds]

Yes they crack around the canister exit pipe welds. The sides of the can are thinner than the main body surround. I personally feel it is a flawed design due to the fact they put the rear hanger supports in these exit pipes the heat/cool cycles and vibration especially at cold start results in weld fatigue cracks. That is why i had the fab shop not one weld the cracks but also support the exit pipes. Gone is my extreme cold start vibration....

[damageprone]

Originally Posted by jmg

Just got a call from my SA. MPE needs to be completely replaced! Turns out the valve is completely shot. It's currently backordered but should be coming from Germany in a little over a week. I'm glad i'm still under warranty!!!!

Any update on your replacement? My SA also confirmed the backorder and haven't heard from him in about a week.

[jmg]

Originally Posted by damageprone

Any update on your replacement? My SA also confirmed the backorder and haven't heard from him in about a week.

MPE was on backorder, but not long, my dealer got it in just over a week. Installed soon after, and now the rattle is gone! I did notice that they did not replace the CF tips though, just the exhaust.