It have put together leak down tester similar to this one (- vmaxoutlaw.com/tech/leakdown_tester.htm ) using some spare stuff that I had . I specifically want to check a 603 diesel so I used an old injector housing insted of a spak plug . What is an acceptable rule of thumg leak down at 100 psi for Mercedes gas and diesel engines ( any links to charts would be nice ) ? Any other suggestions on doing the test are appreciated ?