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Q: Rattling noise rpm jump

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I bought my truck with 64,900 miles on it. It still has the stock DPF - Diesel Particulate Filter on it. I noticed an engine rattling noise around 2000 rpm when I pressed lightly on the gas pedal. It didn't make the sound when I pressed down and increased my speed while driving. I had it idling for about an hour, started to drive and the turbo waste gate was acting weird and running really bad. It sound like it had a blow off valve that it doesn’t have. It hardly moved then suddenly jumped up 20 PSI and the rpms would jump too but not sure how much. Once running at a steady speed it sounded like a loud race car with rpm fluctuations. I'm not sure if it was still rattling. The more I drove it the better it got. It was finally normal after driving a half an hour, but still had the rattling noise in the engine. I was pulling a 25 foot trailer with a compact car inside. Do you have any idea what is causing these problems?

Hello there. It sounds like there may be a few things going on. The noise could be a number of things, such as the belt idler, engine misfire, injectors, engine mechanical damage, or the turbo. A rattling noise is not normal operation and should be looked at as soon as possible to avoid further damage and dangerous scenarios. Have a qualified technician, such as one from YourMechanic, diagnose the rattling noise and perform any repairs required.

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