12-07-2017, 02:19 PM | #1 |
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Rattle, Smoke at Cold Start
Hi, I'm a new owner of a 2011 E70/N55 with around 81k miles. I have noticed two problems in the two weeks I've owned the car and am wondering if they're related. I've done a bit of Googling and could use some advice on next steps instead of just starting "part swap roulette" (which since we're talking engine-related gets expensive fast). Or it may be that I just need to find myself a good indy and let them handle since it's a more complex issue.
First problem: noticed almost immediately that there was a rattling sound from under the car on cold start which goes away pretty fast, maybe within 15-20 seconds. Sounds like a loose exhaust pipe or shield, but if it were that the sounds wouldn't go away. Some Googling seems to indicate that it might be the turbo wastegate. Second problem: happened this morning for the first time. Cold start (but warm and humid, outside temp around 80) threw a ton (almost comical) of mainly white smoke out the exhaust. At the time I didn't think to see if it had a tint, but it didn't have much of a smell that I could detect and it completely stopped within 30 seconds. Subsequent starts on the same trip were smoke free. Googling shows a bunch of possible causes from valve seals to turbo seals. I'm going to have my camera ready for the next cold start. Anyone have thoughts or areas where more info is needed? BTW, I'm new to BMWs but have done work on all of our previous cars, one of which was a Mercedes C320, and I'd call myself an intermediate shade tree mechanic. I'm not pulling any engines, but I'm willing to try almost anything else. Thanks! Matt |
12-07-2017, 02:49 PM | #2 |
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I didn't have a rattling issue, but I did have a smoking issue.
I did exactly what you're trying not to do (replace a ton of shit to see if it works). It ended up being the turbos that were causing the smoke. When the indy shop removed the old turbos there was a bunch of dried up burnt oil so apparently the turbos were clogged up and had started leaking. Replaced the turbos and the problem was solved. This was after replacing injectors, coils, a tone of hoses, all sorts of shit, almost replaced the valve seals (thank go I didn't). Needless to say it broke the bank, but god damn it its back and running better than ever. Hope this helps.
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12-07-2017, 04:29 PM | #3 |
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Being that the N55 is just a most cost effective (read less complicated) version of the N54, I'd guess the rattling is from the wastegate as well. As for smoking, that could be seals or MAYBE the injectors, but it's my understanding that the N55 went away from the fancier (and more problematic) piezo injectors the N54/N63/S63, etc used and the N55 is back to more traditional injectors. One way I could tell the injectors we're about to fail (knowing better now after the fact) is that I was getting black peppering all over the back of my truck, which turned out to be unburnt fuel...once morning cold start went from being loud to pluming smoke and lumpy idle.
If I were you, I'd post this thread over on N54Tech since that engine is used on thousands and thousands on 1, 3 and 5 series cars...you'll have a FAR broader audience of experience vs here where the only thing you mostly share in common with the rest of us is a body style.
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12-08-2017, 03:59 PM | #4 |
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I remember having a loud rattle at coldstart with my 335i. It was a little actuator in the left-hand side of the exhaust pipes that closed during cold starts. Does the x5 have this or not?
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12-11-2017, 01:38 PM | #5 | |
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