[drhockey17]

I pulled my engine due to something wrong internally in Cylinder 8. I have the block almost completely stripped. I was looking through my exhaust ports and saw some discoloration in my valve stems. These look a lot different than the other 7 ports and of course the discoloration is in cylinder 8. I am trying to diagnose as I tear the engine down and I'm sure will find out more when I take the heads off and the cylinder heads out but what is this discoloration a sign of? Here are some pictures. you will notice that the picture the valve stems look almost orange in color. All the other ports look like the second picture (just usual carbon build up).

Any insight would help greatly.

 

[fordman777]

That's how plugs look when you're running lean. What exactly was going on? Any misfires or running rough for example?

 

[drhockey17]

Runs ok. Has a horrible ticking sound. I ran an engine treatment through it and helped a little but still pretty bad

 

[JonR2006]

I was thinking overheating...but I'm honestly not sure....these are 4V heads. C or B heads? I know the Cs had an overheating issue on cylinder 8 which is why I was leaning towards that...

 

[fordman777]

http://www.modularheadshop.com/cobraheadtick.aspx

Is that the driver side head?

 

[drhockey17]

I think I have a similar problem. It is the rear cylinder on the driver side. I have an '01 cobra. Naturally aspirated. But I think that the owner before me beat the snot out of this car. This article would explain the low compression and the ticking noise, but when I did a leak down test the air was coming through the bottom part of the engine. I guess I will find out more when I take the heads off. Perhaps i have more than one issue with that cylinder. Bad valve seals and piston rings are what I am guessing.

 

[fordman777]

http://www.modularmotorsportsracing.com/prod_dohc.htm

5th and 6th items down.

 

[drhockey17]

thank you!

 

[fordman777]

I'm just taking a guess considering I have never dealt with the 4V's nor there to fully diagnose the problem. However I know that it looks like that cylinder probably had some detonation considering the look of those valves. You got the heads off yet?

Your welcome! It's what the forums are for.

 

[drhockey17]

no i have not. I was gone all weekend. I am going to get back at it tonight and should have the heads off. I will post pics of what i find

 

[drhockey17]

I took the heads off tonight and nothing looked suspicious (picture 1). I then took the two exhaust valves out just to make sure everything was good and it was. After that i dropped the oil pan (pic2 and 3) and sure enough I found the problem. #8 cylinder is chewed all to hell (pic4). I then inspected the cylinder walls and there is a little minor scoring (pic 5) but I don't think it is that bad. I should be able to hone it out i think.


Do you think that it got overheated?