BG: Noise in motor !
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BG: Noise in motor !
Hello,
I have the following issue with my car. It’s an Audi A8 D3 4.2 FSI. When the engine warms up, a knocking sound starts coming from the top of the engine. Fuel consumption has increased. When I rev the engine, the noise decreases, but as the RPM drops, the knocking resumes. There are no error codes.
The mechanics at the service center suggested it might be the timing chain, but there’s no rattling, scraping, or knocking during a cold start. The noise only appears when the engine warms up. The oil pressure warning light is not on.
About three months ago, the knocking sound started suddenly after I left the service center, where the alternator had been replaced. Back then, they also said it could be the timing chain or something else. They changed the oil and removed the swirl flaps, claiming the car was fixed.
After driving for another three months and approximately 2000-3000 kilometers, the same noise has returned. There’s no loss of power, no vibrations—just this knocking sound. I’ve attached a video for reference. I’d be grateful for any ideas or shared experiences regarding this issue.
Thank you!
I have the following issue with my car. It’s an Audi A8 D3 4.2 FSI. When the engine warms up, a knocking sound starts coming from the top of the engine. Fuel consumption has increased. When I rev the engine, the noise decreases, but as the RPM drops, the knocking resumes. There are no error codes.
The mechanics at the service center suggested it might be the timing chain, but there’s no rattling, scraping, or knocking during a cold start. The noise only appears when the engine warms up. The oil pressure warning light is not on.
About three months ago, the knocking sound started suddenly after I left the service center, where the alternator had been replaced. Back then, they also said it could be the timing chain or something else. They changed the oil and removed the swirl flaps, claiming the car was fixed.
After driving for another three months and approximately 2000-3000 kilometers, the same noise has returned. There’s no loss of power, no vibrations—just this knocking sound. I’ve attached a video for reference. I’d be grateful for any ideas or shared experiences regarding this issue.
Thank you!
AudiWorld Super User
Joined: Feb 2012
Posts: 2,251
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From: Moronville, Tennessee (Middle TN)
Boy, that's weird. I'm not sure if the purge valve could make that sound, but it's one thing that only operates for a few seconds after starting. I hope that's what it is, because the alternatives are far harder to repair!
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In three car service centers, they couldn't tell me the exact problem with the car. They only made some assumptions related to the timing chain. I changed the oil, and now there's no more scraping or knocking sounds. On Monday, I’m going to a fourth service center to see what they say. I'm starting to think it might be the vacuum pump.
Thread Starter
AudiWorld Newcomer
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Ok, i try that. Thank you !
Another thing I noticed is this: I bought the car with an LPG system installed. When the car runs on gasoline alone for a long time, it starts making a grinding noise. However, when it runs on LPG, there are no issues at all.
Another thing I noticed is this: I bought the car with an LPG system installed. When the car runs on gasoline alone for a long time, it starts making a grinding noise. However, when it runs on LPG, there are no issues at all.
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