That one vacuum leak that took me 4 hours to find

Had an '02 F150 come in last month with a rough idle that had me chasing my tail. Checked the MAF, cleaned the IAC, even swapped the plugs. Finally broke out the smoke machine and found a tiny crack on the PCV elbow hidden under the intake plenum. A $3 part and 4 hours of my life I'll never get back. Has anyone else had a simple fix hide like that and make you feel like a fool?

3 comments

3 Comments

christopherwilliams25d ago

...and that's the thing, it's never the expensive stuff that breaks, it's always some stupid little rubber piece that's been baking for 15 years. I had a similar deal on my old Silverado where it was stalling out randomly and I spent two weekends swapping the fuel pump and filter, which was a huge pain. Finally got a can of brake cleaner and started spraying around the intake and found a tiny split in the vacuum line going to the brake booster, the one that goes behind the engine. That $3 line and a pair of pliers and it ran like a champ again, made me wanna kick myself. Smoke machines are great but sometimes the old school way with some brake clean and a prayer is faster.

joseph4481mo ago

Oh yeah, that "4 hours I'll never get back" hits too close to home. I spent a whole Saturday chasing an intermittent misfire on my neighbor's Civic, replaced the coils and everything, only to find out the spark plug wire was just barely touching the exhaust manifold and melting a little. $12 fix after 6 hours of my life gone poof. Makes you wonder if smoke machines are really worth it or if they just give us more excuses to stare at engines.

shah.olivia1mo ago

Oh man, @joseph448 you just reminded me of a similar nightmare I had on my own CRV. Smoke machine actually helped me find a vacuum leak that I'd been chasing for two weeks, but it ALSO made me replace a perfectly good intake gasket because I didn't clean the smoke residue off first and thought it was still leaking. These tools are amazing until they're not, and then you're just standing there with a $200 machine wondering if you're making problems up. The misfire thing though, that's brutal. Spark plugs are always the LAST thing I check because I'm stubborn and think "no way it's that simple.