Basically, the timing belt (inside the black plastic cover) is too loose and slapping the cover. I reach in (not safe--do not try at home) to pull the cover away and the noise dissipates.
The solution was to take the car in, and using the Porsche 9201 tool (an expensive $5-600 unitless custom tension tool) to tension the belt to a nominal 3.5. This eliminated the noise, but the engine still runs rough (on three cylinders) until warming up. This is apparently the symptom of a bent valve that somehow is alleviated as the valve metal expands and fully closes the combustion chamber for one of the cylinders.
Basically, the timing belt (inside the black plastic cover) is too loose and slapping the cover. I reach in (not safe--do not try at home) to pull the cover away and the noise dissipates.
ReplyDeleteThe solution was to take the car in, and using the Porsche 9201 tool (an expensive $5-600 unitless custom tension tool) to tension the belt to a nominal 3.5. This eliminated the noise, but the engine still runs rough (on three cylinders) until warming up. This is apparently the symptom of a bent valve that somehow is alleviated as the valve metal expands and fully closes the combustion chamber for one of the cylinders.
ReplyDeleteNot a bent valve. Problem was a broken valve spring that thermally grew to alleviate the crack. spring replaced
ReplyDelete