Wastegate rattling noise between 1500 - 1700 rpm

[Shubacca]

Originally Posted by chrison600

I spoke with an old friend today who is a BMW master tech (still active). He could not find an official TSB in this regard. He wondered if the repair was an attempt to take out slop where the valve shaft had worn the turbo housing. He is aware of fixes where the turbos are removed and bored out for new shaft bushings. I was wondering if you thought or knew if this was a shaft/housing interface issue, or an actuator linkage issue.

I may dig around on the turbos myself to see if I can find or narrow the source of the vibration.

I haven't had a chance to actually get my hands on the turbos to see if it's something external that I can obviously identify. I do have a hard time believing that it's a worn shaft in the turbo housing since my S55 only has 16k mi on it, but I suppose anything is possible. Plan is to start with linkage and go from there.

I won't be able to dig in until the middle of September, so let us know if you make any headway!

Pic below is where I plan to focus first. Ignore the cracked manifold haha. Just a random image I found.

[Padsie]

I have this same issue. Dealer believed the issue to be down to the valves in the exhaust so replaced the rear silencer under warranty. Picked the car up and on the way home the noise seemed worse. Due to the logistics of taking the vehicle back to the selling dealer I would be interested if this does fix the issue as its driving me mad

[chrison600]

Originally Posted by Padsie

I have this same issue. Dealer believed the issue to be down to the valves in the exhaust so replaced the rear silencer under warranty.

If the noise is the same as mine (difficult to compare without audio/video files), it is definitely not in the exhaust flaps. My car is equipped with a full AWE Switchpath exhaust system, which does not use the factory flaps.

I plan on at least getting an e-clip assortment similar to Shubacca and doing some diagnostics. I'll be installing charge pipes soon, so may wait until I have all of that taken down before diagnosing any wastegate actuator vibration. Depends on how easily I can get to those actuators.

Chris

[ogakul]

Any updates?

[Shubacca]

Originally Posted by ogakul

Any updates?

Planning on trying some e-clips out tomorrow afternoon. If I get around to it I'll make sure to report back.

Edit: went for a 4 hour drive instead of messing with the WGs.

[Shubacca]

Update: very unexpected but since installing my AA single mid pipe, the rattle has all but disappeared. It's hard to tell, but I think I get a very quiet very short rattle at 1800 rpm in efficient mode, but I struggled to replicate it. Can't hear it at all in sport, which I used to be able to. I realize the exhaust is louder now, but still.

I might still try to put an e-clip on, but now it's got me thinking the rattle was elsewhere. I also have a mic set-up for my exhaust so I'll drive it normally with that on to see if I can capture it.

Update 2: was installing an OCC so I had the passenger side airbox out and had a clear shot to the forward WG components. The e-clips I got off of amazon will definitely not work for this application. There is about .1mm of space for a shim, and these clips are easily .5mm wide. The arm pictured below has some serious lateral play in it and just shaking it and tapping it with a screwdriver makes a metallic "clink" that would 100% result in a high pitch rattle if at the right RPM - HOWEVER, I am still not experiencing the level of rattle I was before the AA midpipe. My only guess is that the new exhaust has a different harmonic frequency and doesn't shake the wg arms the same as stock.

The top connection has a cotter pin type fastener, and you most certainly could bend it so that it would maintain pressure on the arm. That might work. Otherwise if the rattle bothers you enough, pull the pin and put a very thin shim or even rubber gasket of some sort. I'm personally over it unless it gets worse somehow.

[schlichtm3]

Have and now also hear the rattle. Is there any new info here yet, has anyone been able to elemenate the rattling with the e-clips?

[1000hp]

I had my downpipes off yesterday and took a look at the wastegates.
Mine rattle quite a bit, but they do that when the wastegate flaps are open. Both flaps were open the same amount. Closing the flaps would have taken up the slack, and the actuator arms are adjustable. But, the wastegates are designed to remain open on cold start to help heat the cats. Closing the gates with the adjustable arm could cause serious boost issues.

Also, shimming the actuator arms might not be a good idea, as those parts will heat up a LOT, and could expand quite a bit and take up that small gap. Shimming it might tighten it up enough to prevent it from working. You don't want the wastegate stuck open, and you REALLY don't want the gate stuck closed.

I think the audible rattle may have more to do with the opened-up exhaust than the wastegates themselves.
If any of you have tune software that allows you to disable cold start, try that and see if that changes anything. That should eliminate the opened wastegates at cold startup.

[schlichtm3]

Today I have both arm ends with sealant, like plasticine, provided. So that the arms can no longer rattle and the rattling has not changed in any way, so neither the sound, volume nor duration.Therefore, the rattling definitely does not come from the two loose wastegate rods.

[1000hp]

Originally Posted by schlichtm3

Today I have both arm ends with sealant, like plasticine, provided. So that the arms can no longer rattle and the rattling has not changed in any way, so neither the sound, volume nor duration.Therefore, the rattling definitely does not come from the two loose wastegate rods.

Where did they put the sealant?

[schlichtm3]

See Post and Photo #28 and i put it in the Gap(s) - so wenn you will Rattle with your Hand there is no Rattle anymore. But when you Drive, there is no, no different with or without sealing the Gaps. Somit must something different.

[1000hp]

Originally Posted by schlichtm3

See Post and Photo #28 and i put it in the Gap(s) - so wenn you will Rattle with your Hand there is no Rattle anymore. But when you Drive, there is no, no different with or without sealing the Gaps. Somit must something different.

If it's coming from that area, it's probably the wastegate flaps. I should have taken a video when I had the downpipes off. The flap itself will rattle around when it's open and not under any pressure. And the flaps are open at cold start and probably partly open for the first few minutes of driving after cold start, when not in boost.

[schlichtm3]

Thx for your anwser and Infos.

I have it but at low revs at around 1000, if I give little gas you hear it a second or little gas hold, then all the time. As I said reproducible at around and at 1000 - 1200 rpm and also only when driving. Not when stationary in neutral. When driving and accelerating or at over 1200 you never hear the rattle.

[1000hp]

Originally Posted by schlichtm3

Thx for your anwser and Infos.

I have it but at low revs at around 1000, if I give little gas you hear it a second or little gas hold, then all the time. As I said reproducible at around and at 1000 - 1200 rpm and also only when driving. Not when stationary in neutral. When driving and accelerating or at over 1200 you never hear the rattle.

Does it happen when the car is warm, or only at cold start? And do you have the OE downpipes on the car?
I can hear mine rattling at cold startup, but it's gone within a minute or so of running. It was also completely absent when I went back to stock downpipes, and is back after once again installing high-flow cats.
I'm pretty sure that particular noise is the wastegate flaps and not the actuator arm. The flaps themselves rattle around even when the arm is held in place.

If it really bothers you, you could find a solution like the ones offered for rattly N54 wastegates (see pic).

[schlichtm3]

Thanks for your info, that helps me a lot.
My car is completely stock incl. downpipes.
You can hear it on cold start of course, but also when the car is warm (actually at any operating temperature) and then in the 1000 to 1200 rpm range when you give little throttle or hold throttle in that range.
The question is, so at least is discussed here in Germany, that the replacement sleeves also do not last long.

The question I ask myself is, can I continue to drive with it or is possibly even more broken because the flaps wear and no longer seal properly.

[1000hp]

Originally Posted by schlichtm3

Thanks for your info, that helps me a lot.
My car is completely stock incl. downpipes.
You can hear it on cold start of course, but also when the car is warm (actually at any operating temperature) and then in the 1000 to 1200 rpm range when you give little throttle or hold throttle in that range.
The question is, so at least is discussed here in Germany, that the replacement sleeves also do not last long.

The question I ask myself is, can I continue to drive with it or is possibly even more broken because the flaps wear and no longer seal properly.

Well, if they no longer seal properly you will probably not be able to achieve full boost. Or it may take longer to reach boost threshold (increased turbo lag).

The worst case scenario would be the wastegates getting stuck closed, which would cause extremely high boost and probably blow the engine. But the chances of that happening are pretty slim.

If you're concerned about the flaps being loose enough to fail in some way, you can remove the downpipes to check them. With the downpipes removed you'll have free access to see and touch the flaps, and can decide for yourself whether they seem loose enough to cause a serious problem. I haven't heard of anyone having a total wastegate failure. Maybe someone else here has?

[Shubacca]

Interesting that silencing the arm didn't fix the issue - I was really hoping it would. Mine rattles so consistently at 1800 rpm in every condition that's it's uncanny. If it's the actual WG flaps that kinda sucks.

[1000hp]

Originally Posted by Shubacca

Interesting that silencing the arm didn't fix the issue - I was really hoping it would. Mine rattles so consistently at 1800 rpm in every condition that's it's uncanny. If it's the actual WG flaps that kinda sucks.

Time for upgraded turbos!

[f80bm3]

I had this exact same rattle and the dealer told me it was normal after they replaced the entire midpipe... Picked up the car when they were done and the sound was worse. I ended up replacing the crush gaskets in between the downpipe and midpipe, made sure those bolts were tight and it fixed the issue. Idk why the dealer couldn't get that right but for my case at least, it was definitely that connection in the exhaust. Also haven't had the issue after switching to an AA EL mid pipe. Hope that's helpful!

[billypopo]

Exact same thing here with my f87. Appointment at the dealer next week..

[DrewDDS]

Originally Posted by f80bm3

I had this exact same rattle and the dealer told me it was normal after they replaced the entire midpipe... Picked up the car when they were done and the sound was worse. I ended up replacing the crush gaskets in between the downpipe and midpipe, made sure those bolts were tight and it fixed the issue. Idk why the dealer couldn't get that right but for my case at least, it was definitely that connection in the exhaust. Also haven't had the issue after switching to an AA EL mid pipe. Hope that's helpful!

Did you notice any soot buildup around the connection?

[F82///M]

Hope this helps someone.
I had this rattle since last September, waited for the next service since it's still under warranty. Today got new MPE and it's fixed. It seems like it was one of the exhaust valves or internal muffler damage. They have replaced everything from cats back, luckily got even new CF tips as well.

It would happen around 1500rpms as it's seen in video. In lower gears it happens too fast to notice so this is the best way to replicate. Even Bmw tech didn't hear it until I've shown him a video, went for another drive and just said it needs new exhaust.
Also upon cold start, about 20 seconds later with rpms coming down it would rattle for about 3 seconds. It was also noticeable taking off in 2nd gear giving it more load.

Car is stock 2018 ZCP with MPE since new. Rattle was louder with CF tips removed as it was the case in video and the sound was recorded using a microphone placed inside the trunk.