I'm currently working on a friends `92 DX Sedan, and I started today on what I was hoping to be a head gasket replacement. When I finally got down to it, and flipped over the head, I noticed that one of the valves in the right most cylinder had a 1/4" hole burnt through it. There was also black/white burnt gunk on the spark plug for that cyl, and also sitting on top of the piston. The gasket had a bit of a crack in it, but it wasn't the worst I've seen. We're still deciding what to do with this beast (I've almost got him talked into just doing a nice swap), but I'm curious as to what would cause this. Any ideas?

also, I'd like to hear from people that have moded sedans on how they like them compared to a coupe or hatchback.

thanks,

 

White gunk on the plug usually means detonation, which is quite likely what happened to the valve.

The black stuff is probably natural deposits + maybe a little oil.

It probably wasn't leaking coolant into the cylinder, that should have steam-cleaned those deposits off the piston.

 

Have to see how much it costs to replace that valve. Then compare that price with another D longblock and go from there.