Rebuilt cylinder head... now there is a loud rattle

[HITNRUN]

Hi everyone. I've rebuilt many cylinder heads and this is the first time I have encountered this problem. I rebuilt the cylinder head on a 90 TSi AWD. I started the car and it seemed ok. About 5 minutes later I noticed a taping sound. It was very quick and I couldn't tell if it was going with the valvetrain or the block. Even with a stethiscope I couldn't tell if it was from the bottom or the top of the engine. I removed the oil pan and all the rod and main bearings are ok. The noise is now very loud. removing the valve cover shows nothing. Compression in the cylinders is perfect. Could this be a hydraulic lifter that has failed? Thanks for the help.

 

[playitlouddsm]

This is exactly what is going on with my friends car. Would be nice to figure this out.

 

[BISHILVR]

If you did'nt replace the hydraulic tensioner for the timing belt, I would say the sound is the tensioner arm slapping the tensioner rod because the tensioner is no good and it is leaving slack in the bottom of the belt.

 

[Old Mitsu Tech]

You are going to have to pinpoint the location of the tapping. Like was posted above, anything is possible. I harp everyday on the use of "new" auto tensioners. If you can pinpoint the location, let us know and we can perhaps give you an idea.

Lifters can and do collapse. If bad enough, it can also cause engine miss as they don't open the valves. On these engines the whole rocker will fall off and there you go.

Piston skirts, wrist pins, rods, mains, and counter balancers all can cause knocks.

Tapping noises usually are valve train related though.

Good Luck