just replaced the head after head gasket change all back together running and then a loud tap started randomly and then constant, have found that the 4th exhaust tappet has loud tap on closing.

sortted this nis now a sticky valve can anyone help

I had a very bad tappet noise on my DA, I did the water treatment and now the engine is very quiet you would not know it's running.

Do some reading first. I removed the air filter, revved the engine to about 2000RPM and with a squeeze bottle trowed a stream of water into the throttle body. I did it three times, kept the revs up for a little longer and done. The engine got better and better over a couple of days, but the difference was immediate. No more noisy rockers. It's like a new engine an it's done 337,000KM.

Chicho