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993 TT Cylinder Leak Down vs. Compression Test


Vehicle Information: Year: 1996; Body Type: Coupe; Total Mileage: 58,000;

During a tech inspection by a very good and well respected Porsche only service garage, which became a 60,000 mile service, a cylinder leak down test was performed twice- once cold, again warm. The tests were performed using 150 lbs. of air pressure in a fairly new Snap-On device w/shop air. The numbers were somewhat erratic and as the car is in its last stages of a Porsche used car one year warrnaty, I took the car to both Morong's and Herb Chambers Porsche certified dealerships to have the test results checked out. Morong's told me that their computer showed "absolutely nothing wrong and no reason to go any deeper". Bob Fitzgerald, at Herb Chambers, compression tested the car and computer scoped it (finding the upgraded computer with a unique VIN). The compression test yielded perfect numbers. He too declared the car was perfect and to disregard the leak down test numbers. "No reason to go further". The car's drivability was emphatically approved by both certified service guys and the car does not use or burn oil or overheat. In my opion, too, the car goes like a bat out of hell! Which test is the "best"? Which test results should I consider aberrant? What is your opinion on how these numbers could be different? Can these tests show different results? How do I interpret the differences? Thanks!

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