986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Please confirm my diagnosis of one bad O2 sensor

JFP in PA · 01-18-2016, 09:59 AM

I'm sorry, but that is complete nonsense. Vacuum leaks occur due to pressure differential, there is lower pressure inside the system (engine vacuum) than outside (atmospheric pressure). So unless you use a machine to pressurize the engine above atmospheric pressure with smoke, there will be no leak. And if you did internally pressurize the engine with smoke, you would have smoke pouring out the air intake and exhaust, and probably would start blowing off every vacuum connection on the engine.

We smoke test cars for vacuum leaks just about every day, and is not done by blowing smoke into the engine, period.

01-18-2016, 09:59 AM	#19
JFP in PA Registered User Join Date: Feb 2005 Location: It's a kind of magic..... Posts: 6,279	I'm sorry, but that is complete nonsense. Vacuum leaks occur due to pressure differential, there is lower pressure inside the system (engine vacuum) than outside (atmospheric pressure). So unless you use a machine to pressurize the engine above atmospheric pressure with smoke, there will be no leak. And if you did internally pressurize the engine with smoke, you would have smoke pouring out the air intake and exhaust, and probably would start blowing off every vacuum connection on the engine. We smoke test cars for vacuum leaks just about every day, and is not done by blowing smoke into the engine, period. __________________ “Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein Last edited by JFP in PA; 01-18-2016 at 10:04 AM.