Can we talk about using a compression tester vs a leakdown tester

I used to think a compression test told you everything you needed to know about an engine's health. Then I had a 2002 F-150 come through my shop in Phoenix last month that showed 150 psi across all cylinders but had a miss at idle. Pulled out the leakdown tester and found 30% leakage on cylinder 3 through the intake valve. Now I'm wondering if I've been missing stuff for years. Anyone else switch their go-to diagnostic tool after getting burned?

2 comments

2 Comments

lisa_grant1mo ago

Yeah "150 psi across all cylinders" is like judging a book by its cover.

faith_thomas1mo ago

Compression tests tell you surface level stuff but not the whole story.