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That one Wednesday where a coolant leak led me to a cracked head on a 6.7 Powerstroke before it blew
I caught it because the truck had been sitting for two days and there was a tiny puddle under the fan shroud, not the radiator, so I pressure tested it and found a hairline crack between cylinders 5 and 6.
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finley_smith7d ago
Wait, you pressure tested it yourself after seeing a puddle under the fan shroud? That's a pretty specific spot to look, honestly. Most guys would've just topped off the coolant and sent it, you know, until the thing blew up on the highway. But a pressure test wouldn't catch a hairline crack between cylinders 5 and 6 unless you let it sit for a while and watched the pressure drop real slow, like over an hour or two. Those cracks are tricky because they only open up when the engine gets hot and expands, not when it's cold on your test. I've seen a cracked head on a 6.7 that didn't show a thing on a cold pressure test, but then had a steady drip from the exhaust after a hard pull, so maybe you caught it with a dye test or something instead?
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robin8967d ago
Well I used to think a cold test was good enough, but you changed my mind on that one.
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troyc177d ago
Man, that's exactly the kind of thing that had me pulling my hair out on a 6.0 a while back. @robin896, you're dead on about the hot vs cold thing. What finally worked for me was running the engine up to temp, shutting it off, and then doing a pressure test while it was still hot. I watched the gauge drop about 5 psi over 20 minutes, and sure enough, when I pulled the heads, there it was a tiny crack between cylinders 3 and 4. Cold test showed nothing, not a single bubble.
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