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That fuel leak took 3 whole afternoons, and I still almost missed it
Fellow mechanics, I need to vent about a 2008 Freightliner that came in last Tuesday with a slow diesel weep near the rear axle. Everyone said it was the return line, but I pressure tested that, dry as a bone. I pulled the tank strap and found a hairline crack hiding under the corrosion, right where the sending unit grommet sits. It took me 12 hours across three shifts to see it, and only because I left it running overnight and came back with a flashlight at 6am. My shop foreman kept saying it's always the gasket, and I nearly trusted him instead of my own eyes. Anyone else ever chase a leak that turned out to be a crack you couldn't see until the whole rig was cold? What's your longest diagnostic rabbit hole that made you question your own tools?
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corad842d ago
Got a 2004 Volvo with a coolant loss that only showed up on cold starts. Same deal, everyone swore it was the water pump weep hole. Cap off, pressure pump, nothing. Finally left it in the alignment bay overnight, came back at 5am and saw a tiny drip on the passenger side engine mount bracket. Turned out the lower radiator hose clamp was stripped and it only slipped when the engine shrank after sitting cold. Took me two days and a lot of bad words. A cold engine and a flashlight beats any scan tool for hard leaks. The trick that worked for me was to clean the whole area with brake cleaner, put some baby powder around the suspect spots, then let it sit. The powder turns dark where oil or coolant seeps in, even if you can't see the drip itself. Made a hairline crack in a dry manifold stand out like a sore thumb.
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