I finally found that coolant leak after 3 days of hunting it down

Was working on a 2015 Freightliner Cascadia last week, the one with the Detroit DD15. Owner said it was losing a gallon every 200 miles but no puddles anywhere. I spent 2 days checking hoses, water pump, head gasket, all the usual spots. Finally on day 3 I got under it with a pressure tester and a flashlight while the engine was hot. Found a tiny hairline crack on the back of the EGR cooler tube, right where it rubs against a bracket. Couldn't see it unless the engine was at operating temp and the metal expanded just right. Slapped a new tube on and it held pressure fine. Anyone else had a leak that only shows up when the engine is hot?

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2 Comments

wood.john5mo ago

Well damn, did you check that bracket for chafing too?

3

calebw505mo ago

A bit of electrical tape on mine sorted that right out.

2