formula223

I have a 94 968. When the engine is started cold it sounds fine, just like a big sewing machine. After a 10 mile drive, at idle, I can hear a repeative knocking at the front, right side, of the engine just about where the front cylinder exhaust valve lifter is. It sounds like it might be a bit lower than the cam but not down into the cylinder. Its as if a mechanical lifter is way out of adjustment but a bit harder and louder. It is continious and is in time with engine rpm. This is only heard after warm up and is not loud enough to hear from inside the car. Otherwise, it runs and preforms as it should.

I removed the cam cover and everything looks new. The cam chain is tight. All the lifters are free and I can rotate them with my finger. Cam lobes "look" fine. Both cam and balance belts look fine. Cam belt is tight and the balance belt semi tight with no slack.

Is it a leaking lifter making noise after the oil thins? Could it be the balance shaft belt loosening up after it gets warm? (The engine doesn't vibrate warm or cold).

Please, if you have any suggestions let me know.

Thanks!!
Mike

SoCal Driver

Is the cam gear tight on the cam?

formula223

Yes, everything behind the belt cover seems to be right. I am worried it may be a rod but I would have thought rod noise would be lower in the motor.