Compression test question...

[Throwback23]

I recently purchased a 97 tsi awd that ran great but heated up fairly quickly. Turns out the headgasket is the culprit, but in testing I noticed something different about the automatic when compared to testing my manual talon. It seems as though the starter on the auto is just soo much slower when compared to the cranking speed of the manual. Is this normal due to the mass of the converter? The tests were done with a fully charged battery on both cars yet I would guesstimate that the manual was spinning 1.5 times faster and you could see it in the way the gauge responded to the compression strokes. I didn't get a chance to check the amp draw of the auto starter but I will soon...That said, I have read that slower cranking speeds affect compression readings and while both motors in my auto and Manual talons test out fine (160across on auto/175 across on manual) I'm curious if that slower cranking speed could actually drops the final numbers or not. Thanks for any help or Input

 

[GRAVEDIGGER]

Slower cranking speeds will not affect the final numbers as long as you crank it over enough times. Usually that number of cranks is somewhere around 5-10, or whenever the needle stops jumping up and has stabilized. And remember to make sure you have the throttle plate blocked wide open or held wide open with your foot on the pedal, so you can get the maximum amount of air into the cylinder.