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Q: Rough idle and low power

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I have a 12v vr6 Jetta. The other day, driving to my job, no problems. When I left, the car is louder than normal, rumbly almost like a v8 and is very sluggish. My timing chain has been making noise so I took the valve cover off and set car to TDC. Cams look to be in line, as I was thinking it may have jumped a tooth. Doesn't seem to be the issue. Any other advice? No engine codes. Wires, plugs, coil pack all replaced recently.

My car has 187000 miles.
My car has a manual transmission.

A: Hi, thanks for writing in. It sounds like y...

Hi, thanks for writing in. It sounds like you have timing chain related problems for sure. The central component, your timing chain, which maintains a critical relationship between the crankshaft, and the camshafts on your engine, has likely chewed up the timing chain guides enough to alter the cam timing. The expanded list of possibilities includes: worn-out timing chain guides, failed timing chain tensioner, stretched timing chain, or, as you mention, one of the timing sprockets has jumped a tooth. All of these components wear with extended mileage such as your vehicle has, and must be serviced. When they are severely worn, cam timing can vary enough to cause a "valve-to-piston collision", leading in most cases to destruction of the engine. Your engine needs a timing chain service, which replaces the chain, tensioner and pulley(s), timing chain guides, gaskets and seals. I would recommend having YourMechanic.com diagnose this issue, provide an accurate assessment of damage, and estimate the cost of repairs. YourMechanic.com can dispatch a mobile, professional mechanic to your location for diagnosis and repairs.

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