Is this a crack in my rebuilt engine head?
Visible marks on rebuilt aluminum heads or used engine blocks leave people unsure if they are looking at a legitimate crack. This uncertainty forces them to guess whether poor mechanic work, a manifold leak, or a hot running tendency actually caused the damage.
What the numbers show
Counted from the threads quoted below. How we count
- People have been saying this in most months since September 2026.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Is this a crack in my rebuilt engine head?
- 1Having a machine shop inspect the partDid this help you?
- 2Testing with a pick tool to see if it snagsDid this help you?
- 3Spraying engine block cleaner to wash away the oil and grime to get a clear view of the metal.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Is this a crack in the block…. Just got a “new” to me car from an old fellah and guess I didn’t check thoroughly enough.”source ↗
“My 5.7 L98 TPI (1988 Corvette Stock everything) engine had been rebuilt by a Corvette shop and the intake blew so I took it apart.”source ↗
“These guys did not do the job correctly. I’m especially concerned because they also put these used rebuilt heads on where this crack is now visible.”source ↗
“I’m assuming it’s a legitimate crack but I wanted some feedback, if a manifold leak, advanced timing, and a hot running tendency was enough to crack these aluminum heads.”source ↗
Where this came up
People with this problem also raised
- 2Why is my fresh engine losing oil with no smoke?
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- 3What extra parts do I need to replace during an engine teardown?
- 6Are my brake rotors ruined if they glow blue after bedding?
- 2How to identify unknown debris found in engine oil pan
- 4How to know if a missing engine nut or bolt is important