i have taken my 98 sti engine to pieces and still not found why i hear a tapping sound when the car is running.The tapping sound is on the right hand side and the tappets are fine, however a mechanic looked at the tappets while they were in the engine and one by one pushed them in with a metal rod . He then said one tappet was easier to push than the others so its the spring on this tappet but im not so sure?
I have also checked the distance on the tappets and two of them are 1 thou out but this same mechanic seems to think this would not cause the noise ?
Also i am putting the engine back together again and i need to know how to adjust the timeing on the belts as i can see a arrow on the wheel but not sure if it means anything?
also does anyone know which way i would open the crank shaft pulley, clockwise or anti? thank you

 

Could be your boost control solenoid chattering. It is mounted on the r.h inner wing

 

Let the Engine tick over and put your ear near to the driver side strut and give the car a few hundred revs, you’ll soon notice if it is the solenoid.

 

gangstor, its not piston slap is it??

the crank pulley bolt, just usual way to undo, anti-clockwise, just put a bar and socket onto the nut (22mm) and smack hell out of the bar with a lump hammer, it'll come undone.

 

thanks for your suggestions people, however here is a update!!i have put theengine back together however the car will not start!!
The car has spark and there is fuel comeing through but the thing will not start...any ideas????thanks