Damaged valve, what could have caused this?

[The_big_dill]

Hey all,

Was wondering if I can get some experienced member help on what these cars could do to cause such a valve failure:

This valve holds 20PSI in this cylinder (3) And only 1 of the valves is damaged like this. Cylinder and pistons are undamaged.

It was misfiring in this cylinder, but I attributed that to low compression.

Any advice is appreciated.

Thanks,

Phil.

[08mzr]

Looks like a burned exhaust valve. Usually caused by the valve not properly sealing.
My gen 2 with 220k had a burned exhaust valve on cylinder 3.

[The_big_dill]

Originally Posted by 08mzr Looks like a burned exhaust valve. Usually caused by the valve not properly sealing. My gen 2 with 220k had a burned exhaust valve on cylinder 3.

Thanks for the reply.

I am going to see if this head is salvageable, but what failing components do you think would cause this problem? I am a little concerned because this car is stock.

[Pu Manchu]

Originally Posted by 08mzr Looks like a burned exhaust valve. Usually caused by the valve not properly sealing. My gen 2 with 220k had a burned exhaust valve on cylinder 3.

what sort of symptoms got you to dig into it?

[08mzr]

Originally Posted by Pu Manchu what sort of symptoms got you to dig into it?

Dead miss. Compression check showed about 10psi on cylinder 3, using a scope and pressure transducer showed pulses in both exhaust and intake during compression stroke on cylinder 3.
I bought it with a misfire, but it was cheap, very cheap.

[08mzr]

I am not the most knowledgeable on this. But from my understanding when an exhaust valve burns it's due to it failing to seal as I've previously stated. They can fail to seal due to carbon, tighter clearances, possibly running lean. I'm sure there could be some other reasons, but I'm not familiar enough with these issues to know them.
Since you've owned the car have you cleaned the valves at all?
Usually the head can be saved. I'd recommend all new exhaust valves to be safe, and also have a good machine shop do the work otherwise you'll be doing it twice. You should also send the injectors out for cleaning and flow testing.

[The_big_dill]

Originally Posted by 08mzr I am not the most knowledgeable on this. But from my understanding when an exhaust valve burns it's due to it failing to seal as I've previously stated. They can fail to seal due to carbon, tighter clearances, possibly running lean. I'm sure there could be some other reasons, but I'm not familiar enough with these issues to know them. Since you've owned the car have you cleaned the valves at all? Usually the head can be saved. I'd recommend all new exhaust valves to be safe, and also have a good machine shop do the work otherwise you'll be doing it twice. You should also send the injectors out for cleaning and flow testing.

Unfortunately I bought these problems, never owned a speed, this is the first. The previous owner said he was revving high with low load on the engine when it misfired once or twice. Then the following day, was misfiring at idle.

Thanks for the advice, I will get the injectors cleaned and tested as well.

[08mzr]

Kind of the same story with mine from the previous owner. He told me he was driving on the expressway when it started misfiring.
As for injector cleaning look through the forums to see who can do them. Most places that clean/test injectors cannot do them at the high pressures Direct Injectors operate at. They may seem ok at the lower pressure and not be OK at high pressures.

[eroler1]

was just reading about a post in the other forums

injectorRX and cleveland injectors
they both clean GDI injectors and they have the shipping option

i heard the cleveland changes the filter inside too
planning of going to send mine soon

[Fstrnyou]

I used injector RX. I don't have any evidence to show they replaced the filter, so they probably didn't. I've heard of some injector places shipping back the old filters in a bag so you can see how cruddy they were, lol.

[mituc]

With that much carbon all over that cylinder it's hard to determine what happened. That valve looks burnt butit's possible it shattered after a big chunk of carbon flew off of an intake valve and was caught between that valve and the valve seat. Once chipped it will just continue to go.

[phate]

The stock exhaust valves are pretty awesome, and in the 10 years I've been screwing with this platform I've maybe seen 3 instances of them failing. You have a lot of gunk buildup in that head, so a flake may have wedged itself in and it leaked over time and burnt. I'd expect other signs of failure on the other valve if the injector was screwed up.

I'd probably just pick up a used head from a junkyard and rebuild it/milled flat.