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67 Cpe 289 C4 daily driver
Had the engine rebuilt in Oct 2018 at a shop I've been dealing with for 15+ years.
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In April, the #6 Ex valve broke at the shaft under the spring. Machine shop fixed it. Two weeks later the rocker on that same valve snapped. Machine shop gave me a new one and i replaced it at home.
Car was running great until yesterday. Really bad noises from the motor just leaving the parking lot at work. I pulled the driver's side valve cover earlier today and now it looks like the #5 exhaust valve has broken at the shaft under the spring just like the previous one...
What might cause this kind of failure?
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Valve guide not perpendicular to the seat?
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Rudi wrote:
Valve guide not perpendicular to the seat?
could be, especially if they put in replaceable valve guides and didn't get everything straight.
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Or didn't get them quite reamed to size...
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Typically caused by valve springs having excessive seat pressure. Broken stems and broken rockers and ultimately cam failure.
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