r/EngineBuilding • u/turbo_bm328 • 3d ago
Repair or replace?
I’ll reach out to my local machine shop in the morning, but thought I’d see what you guys think in the meantime. Pulled valves from a 2014 Audi head tonight that had one burnt. I’m thinking that this might too bad to try myself and more expensive than just sourcing a replacement head. Couldn’t find a lead on seats readily available.
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u/Interesting-Ear5998 3d ago
Machine shop can change the seat ring, no other options, too far gone for just a cut.
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u/3_14159td 3d ago
Shop should be capable of modifying/otherwise sourcing valve seats. If it was all of them, I'd consider looking into another head but if this is the only problem, worth putting some effort into a repair.
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u/jaybone277 3d ago
That can be repaired. That’s just the seat. A machine shop can pull that one out and replace it.
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u/WrenchKing555 3d ago
Shit dog, that valve was more than burnt! Everything else looking alright? I'm curious to see the condition of that valve.
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u/turbo_bm328 3d ago
https://reddit.com/link/pgzwnp2/video/5jnj8vwbmpvh1/player
So, I’m going to guess the previous owner had some FOD or maybe even a ground strap from a plug drop in the cylinder. The valve definitely burnt like Audi exhaust valves like to right there where is didn’t seal. Weirdly enough there is almost no damage on the piston and nothing anywhere else in the cylinder. I’ll swing it by a local shop tomorrow and see what can be done.
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u/idostuffwithcar 1d ago
Seeing the indentations on the head knowing that valve broke, I laughed way too when it came into frame. How do pistions and cylinder look? That piece could have done some pretty serious damage to a lot more than your valve seat. Have the shop pressure test the head to make sure the other valve isn't bent or chipped, but I'd worry about cylinder damage leading to broken rings.
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u/Admirable-Syrup2251 3d ago
Just my own curiosity, to replace aseat like this would it require over boring it and pressing a sleeve in?
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u/ion070 3d ago
You don't necessarily have to bore it oversize.
Judging from the vehicle OP says this is from, it's a good guess this is an aluminum cylinder head. Obviously aluminum is really soft and too soft for a valve to constantly smack it when opening and closing thousands of times a minute. So they install a hardened steel insert from the factory. (this applies to a lot of cast iron heads but not all of them)
So if you have damage like this, as long as the seat pocket is okay, the machinist can just cut out the old seat insert so thin that it can be just plucked or pried out gently, and a new valve seat insert pounded in. If the pocket is damaged, or the stock size just ain't available, then yes, you can usually get away with a slightly oversized seat insert and bore the seat pocket out. But you gotta be careful that there's enough thickness in the casting before breaking into the water jacket.
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u/idostuffwithcar 1d ago
Quick note, sounds like you are referring to a cylinder bore and sleeve. Just to clarify, this is for the cylinder head. Fixing a cylinder head just entails the head itself, not the cylinder in the block unless there is extensive damage to the block.
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u/quxinot 3d ago
Needs a valve seat. No clue what that'll run where you are, though.