[DSMturbo2]

ok im posting this for 4g63dsm. searched around and didnt find anything quite like this, hell i have never even heard of anything like this. anyway he has a slight problem. he pulled his head off and on cyl 2 he has a hole in one of his exhaust valves!!! i have not seen it but the whole roof of the cyl head is white (more on the exhaust side) im sure he is obviously running a little lean in that cyl. could this be dirty injector? or what? please help out. thanks. Erik

 

[300dollarGSX]

Wow! A hole in the valve itself? Those things are pretty thick, normally the piston would melt long before a valve would have any problems. Did he have a huge exhaust leak where the manifold meets the head?

 

[GSXtsy]

I saw this on my uncle's 91 TSI. But the valve was brand new. Sometimes when the valve is being made, a small air bubble will get trapped and when it heats up, it will pop and make a hole.
We knew that was what happened because he had just installed new valves, and after talking to the company that made them, they said that it can and does happen.

But, I'm not sure if this applys in this cause, because it dosen't sound like the valves were new. But, maybe it could happen more slowly, like cracking first. And when the crack is big enough, a hole will form.

 

[DSMturbo2]

dont think there was an exhaust leak. and the car has almost 200k (or over?) so i dont think that there were any new valves. im a little worried on the fact that this could be a clogged injector tho, because his old in jector from that cyl is on my car right now thanks for the reply's

 

[barney]

Sounds like a burnt valve to me. This is caused by the valve not sealing when closed. The leaking hot exhaust erodes the metal. Reasons for the valve not sealing include a bad grind job or a loose fitting valve guide. Very lame, low compression engines, like a lawnmower engine, can burn a valve.

 

[91TalonTSi]

Valves

Sounds like a burnt valve to me. This is caused by the valve not sealing when closed. The leaking hot exhaust erodes the metal. Reasons for the valve not sealing include a bad grind job or a loose fitting valve guide. Very lame, low compression engines, like a lawnmower engine, can burn a valve.

I have never seen hole burnt through a valve due to impropper seating,bad grind, etc... In that case it would burn around the valve ( between the seat and the valve ) and not through it. The only reasons that I know of would be #1. Detonation. #2. Running WAY lean ( causeing detoation ) or #3. Just running lean period. There are soooo many ways this could happen. If the car is not modified it could be the ECU, Injector, Injector wires, etc.......... I have seen this happen before, But not on a Diamond Star.

 

[barney]

Yeah, it will cut in from the edge if leaking. DSMturbo2 hasn't seen the affected part so this could be what 4g63dsm means - part of the valve is missing. Anyway, this is the common mode of failure.

 

[91TalonTSi]

Ahh

DSMturbo2 hasn't seen the affected part so this could be what 4g63dsm means - part of the valve is missing.

Gotcha. I was taking it in a literal sense.