Is This a Vacuum Leak?

[ChandlarA]

Hello All, New Poster Here,

I have a 2004 Ls V6 that is not wanting to run right at the moment. I recently replaced all of the coils in the car and have since been hearing a hissing/sucking sound coming from the engine. My first thought was that I had missed a vacuum line when putting the air plenum back on the car so I checked all of the connections to no avail. I then also attempted to find a leak with the carb cleaner trick as well as the propane trick. Neither of those offered a solution to my problem. As a last thought I took the plenum back off to check all of the gaskets for the plenum and they seemed to be ok to me.

Am I missing something here? Any help is appreciated. Thank you in advance.

 

[Telco]

Sounds like you might have a vacuum leak, and at the age of your engine it can either be a split in a hard plastic line or a dry rotted rubber line. If the carb cleaner/propane trick didn't work, get a cigar. Engine off, pull a port that lets you put a half inch or so hose into the intake plenum. Puff the cigar up, and blow the smoke into that hose as fast as you can (don't inhale the smoke, even if you are a smoker; you need it all in the hose). Eventually smoke should start coming out of your vacuum leak point.

 

[ChandlarA]

Sounds like you might have a vacuum leak, and at the age of your engine it can either be a split in a hard plastic line or a dry rotted rubber line. If the carb cleaner/propane trick didn't work, get a cigar. Engine off, pull a port that lets you put a half inch or so hose into the intake plenum. Puff the cigar up, and blow the smoke into that hose as fast as you can (don't inhale the smoke, even if you are a smoker; you need it all in the hose). Eventually smoke should start coming out of your vacuum leak point.

I followed your instructions and found the leak! It was the rubber connector for the PCV hose on top of the Plenum. The hole was big enough to fit my finger into! My car and I both thank you for your help!

 

[RigsLS]

Nice one Telco!



The ol' Scotty Kilmer the car guy Cigar find a vacuum leak trick.

https://www.youtube.com/watch?v=zMok2y05jNE





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