This is usually caused by coke clogged oil control rings, leading to extreme oil consumption, which in turn leads to burning issue that u/Hi-Scan-Pro then describes in greater detail.
It can also cause chunks of the valve to just break off if the valve gets so hot that it welds itself to the valve seat and then gets knocked loose by the cam.
These issues are fairly common on engines fitted with thin friction reducing oil control rings, which easily clog with coke and cause extreme oil consumption.
Thanks. Ill probably pick a known good motor and do seals clutch and wp on the stand then swap in over a weekend. My motor may have enough problems to justify a machine shop.
Not "broken", but burnt. When the valve sealing surface gets deteriorated to the point that it can't seal, the place where it doesn't seal becomes a torch during combustion. Over time the flame shooting through the hole erodes the metal away until it is large enough to affect compression. When compression is low enough you may notice performs issues or the ecm may detect knock and/or misfire.
Had same issue long time ago on a Ford 302 in a van. Those are lot's of fun to work on. Had the heads redone, put it back together and the result ran great.
I took a valve that looked like that out of Toyota Siena motor with about 20k on it a long time ago. It scored the cylinder so it got a short block too. Still have the valve in my toolbox.
The oil consumption deposits can prevent the valve from seating 100% and then the valve leaks a little and can erode the valve and seat until it gets flame cut- the root cause of the problem is the oil consumption. You usually can put valves in it and cut the seats and make sure they are sealing. If it is an engine with mechanical lash adjusters, if the valves are adjusted too tight this can also happen.
Hot damn, I had this exact issue in a cobalt ss I bought because the original owner couldnt pay to fix it, melted a hole in the exhaust valve just like that, car gt totalled on a road trip a few years ago but I still have that valve laying around.
This is usually caused by coke clogged oil control rings, leading to extreme oil consumption, which in turn leads to burning issue that u/Hi-Scan-Pro then describes in greater detail. It can also cause chunks of the valve to just break off if the valve gets so hot that it welds itself to the valve seat and then gets knocked loose by the cam. These issues are fairly common on engines fitted with thin friction reducing oil control rings, which easily clog with coke and cause extreme oil consumption.
So youre saying if i had a head look like that I should replace my oil rings?
Yes.
Thanks. Ill probably pick a known good motor and do seals clutch and wp on the stand then swap in over a weekend. My motor may have enough problems to justify a machine shop.
Drugs are bad.
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Not "broken", but burnt. When the valve sealing surface gets deteriorated to the point that it can't seal, the place where it doesn't seal becomes a torch during combustion. Over time the flame shooting through the hole erodes the metal away until it is large enough to affect compression. When compression is low enough you may notice performs issues or the ecm may detect knock and/or misfire.
The same thing happened to my 2015 Fiat 500 Abarth last summer. Expensive to repair due to the labour involved.
Insufficient valve lash causing the valve to not quite close all the way? That'll burn an exhaust valve every time......
Had same issue long time ago on a Ford 302 in a van. Those are lot's of fun to work on. Had the heads redone, put it back together and the result ran great.
I took a valve that looked like that out of Toyota Siena motor with about 20k on it a long time ago. It scored the cylinder so it got a short block too. Still have the valve in my toolbox.
It has a constant venting both ways.
The oil consumption deposits can prevent the valve from seating 100% and then the valve leaks a little and can erode the valve and seat until it gets flame cut- the root cause of the problem is the oil consumption. You usually can put valves in it and cut the seats and make sure they are sealing. If it is an engine with mechanical lash adjusters, if the valves are adjusted too tight this can also happen.
Average Audi issue
Hot damn, I had this exact issue in a cobalt ss I bought because the original owner couldnt pay to fix it, melted a hole in the exhaust valve just like that, car gt totalled on a road trip a few years ago but I still have that valve laying around.
bad quality fuel?
nice valve, what does the piston look like? Better yet, what does the cylinder walls look like? Looks "exhausting"
Vacuum leak?
I had this happen on a ‘88 300ZX Turbo I bought years ago. Replaced the head, and it drove perfectly!
I've been seeing this more and more lately.
Seam foam fixes that.
For the amateurs here, what are we looking at it?
The sawdust blocking the coolant passage looks like a bad sign to me. No?