Measuring Crankcase Vacuum

[ramo80]

Hi All.

I'm trying to measure my crankcase vacuum pressure to determine if my AOS needs replacing. Can i do that from the dip stick hole or does it have to be from the oil filler cap.

thanks!

[JFP in PA]

Not all Boxsters have dipsticks, so the common way it to make your own slack tube manometer and attach it to an oil filler cap. Remember that when the system is functioning correctly, you are only looking at a vacuum level of 5 inches of water, which isn't much, hence the homemade manometer............

[ramo80]

awesome thanks!

Mine does have a dip stick. I connected my slack tube to the dip stick hole. i filled the tube with oil rather than water and i got 14 inches!!!!!

using a rough converter i get 11.2 inch of water!!!! can i go with the dip stick test or do i have to make a cap and test it the oil filler way?

[ramo80]

Alright i redid it with water. I get 8 inches of water. That is still higher than 5. I'm guessing my AOS is on its way out. Am i correct?

[JFP in PA]

Eight inches is on the high side, if you hit ten it would be an issue.