What would cause a valve seat to break? Mine broke and tore up my #2 piston in my TTA just trying to figure out if this is common or not. It happened when the car was at idle. Up to that point the car was running great no KR/denotation issues at all. Thanks, Jason
Broken exhaust valve seat
- Thread starter Jas89TTA
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turbodave231
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The valve seats in a stock head are integral to (part of ) the head casting. A replacement seat would be pressed in. What do you have?
Seat usually fail due to overheating.
Can you post a picture?
Seat usually fail due to overheating.
Can you post a picture?
83ttypecooled
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Hi,
That's wierd. Are your heads Champion Aluminum or Iron? I am sure they have pressed in seats, in any case. It must have been loose for a while, though you probably wouldn't have known it.Being a performance part, there isn't much you can do about it,but you should let them know, anyway.This the first I have heard of a dropped seat in many a year. It is extremely rare to have this sort of failure, especially at idle. I guess you have the head off,and it must be a mess, but can you see anything interesting? Please let us know the outcome. Good luck with this unusual problem!
That's wierd. Are your heads Champion Aluminum or Iron? I am sure they have pressed in seats, in any case. It must have been loose for a while, though you probably wouldn't have known it.Being a performance part, there isn't much you can do about it,but you should let them know, anyway.This the first I have heard of a dropped seat in many a year. It is extremely rare to have this sort of failure, especially at idle. I guess you have the head off,and it must be a mess, but can you see anything interesting? Please let us know the outcome. Good luck with this unusual problem!
blown okie
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did it actually drop a valve seat insert, or did the valve pound the original seat in?
turbodave231
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Looking at the failure, a couple things come to mind. The original interference fit may not have been adequate to retain the seat. Typical press fit range in cast iron is .002-.003. Continued overheating of the seat can loosen/relax the fit over time. Looking closely at the seat may reveal a few clues about what happened.
How bad did the seat/valve damage the piston/cylinder wall? Hopefully not too bad.
If you plan to reuse the heads, I'd remove and replace all 6 exhaust seats. Running a bead around the seat with a TIG welder works the best for a pressed seat removal. It looks like you still have enough material to go with a slightly larger OD seat.
Exhaust seat material is critical in a turbo engine. A Steel alloy seat or a Powdered Metal seat would work well and not break the bank. Copper Berillium is a great choice but pricey. Durabond has some very nice PM seats designed for severe applications. Whatever seat you choose, be sure your machinist follows the manufacturer's recommendations for press fit.
How bad did the seat/valve damage the piston/cylinder wall? Hopefully not too bad.
If you plan to reuse the heads, I'd remove and replace all 6 exhaust seats. Running a bead around the seat with a TIG welder works the best for a pressed seat removal. It looks like you still have enough material to go with a slightly larger OD seat.
Exhaust seat material is critical in a turbo engine. A Steel alloy seat or a Powdered Metal seat would work well and not break the bank. Copper Berillium is a great choice but pricey. Durabond has some very nice PM seats designed for severe applications. Whatever seat you choose, be sure your machinist follows the manufacturer's recommendations for press fit.
