The injector cup leak that showed up overnight after 4 years of nothing

I've got a fleet of International trucks I maintain for a logging outfit outside Eugene. One of the 2018 DT12 engines had zero issues for 4 years, then last month I pulled into the shop after a long haul and saw a puddle of fuel under the valve cover. Pulled the cover and found two injector cups had developed hairline cracks right at the seating surface. The weird part is they didn't seep or drip gradually. They held fine until a cold morning hit 28 degrees and then let go all at once. I've talked to a couple other local mechanics who say this is common on these engines after they hit 300,000 miles because the aluminum around the cups gets brittle from heat cycles. Has anyone else seen this sudden failure pattern on DT12s or was my batch just cursed?

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patricia424mo ago

That 28 degree cold snap likely caused the aluminum to contract around those hairline cracks.

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parker2244mo ago

Yeah I've seen this same thing happen on some older window frames when the temperature drops like that. Best thing to do is get a hair dryer on low heat and warm up the area slowly before trying to open or close anything. Once you get it free, clean out the cracks with some compressed air and seal them up with a flexible caulk before next season.

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