Cobra issues... Any thoughts?

[Phish]

Last night Jordan and I came across a strange issue when working on a Cobra. To start things off, it had no compression on Cylinder seven. We are thinking the worst but decide to take a closer look. I get a borescope and look in the plug hole and everything looks grand. We want to check the valves so we pull the blower off. All intake valves look excellent. Decide to go a little deeper and check out the exhaust valves. We pull the valve cover and Jordan discovers something that we though was going to be a quick fix and have the car up and running in no time. The rocker was off the valve on the farthest exhaust valve to the back of the car.

Even with the rocker off, the spring looked to be compressed a little. We kept compressign the spring and releasing it and eventually it released and came back to normal operation. Pulled a compression check and WHAM... compression!Jordan snaps the rocker back on quick like and we compression test again. ZERO compression. Rocker off... compression like a champ. Rocker on... none what so ever.

We assume the rocker has issues from coming off and hanging out in the head for about 50 miles of driving (looks good though). So we remove the rocker off of the other exhaust valve, put it on the valve we are having issues with and leave the rocker off the new valve. No compression once again. Its not the rocker. We take off both rockers just to double check ourselves. and we have compression.

We are now getting to be pretty stumped over this. The valve seats fully and is easy to move up and down so we dont think its a bent vavle. We checked the spring out and it does not seem to be broken or cracked. Anyone have any ideas of what this could be. Obviously the head is going to have to come off and gone through. But this is just a little mind boggleing.

Let the thoughts start rolling guys...

[c_mart_28]

Weird.

I don't have any beneficial input but I'm anxious to see what people think.

BTW, this is a '03 Cobra Phish is talking about.

[slow ride]

Over rev might have caused piston to valve issues and bent the valve causing it to bind in the guide. Rocker keeps falling off as it's not loaded at times. Is the lash adjuster/lifter ok?

[Phish]

If the valve was bent then woudlnt it not seat or seal when the rocker was off the valve. Not only does it have compression but its excellent compression when the rocker is not there. Everything looks good as far as the rocker and its install goes. It fits nicely onto the valve and the oiler and there is no slop or play when its installed. Tight to the cam.

[Phish]

[skipdownstairs]

Im thinking perhaps the valve may be binding in the guide also. I would remove the retainer and spring and check to make sure that the valve moves perfectly freely then throw that spring in a checker to check the spring pressure something is a miss and you will find it I'm sure, just hope the head doesn't need to come off may be a bad/weak spring???

[skipdownstairs]

Only other thing that comes to mind is the lash adjuster like what slow ride said take a look at that and or put a new one in there just to be sure

[Phish]

We swaped the adjuster with the valve next to it also. It had no effect on anything so it would not be the issue either. I am thinking we can pull the spring out and see if the valve has any issues moving in the guide.

[slow ride]

Not sure what resolution that bore scope has, but check the piston over to see if it might have a slight sign of valve contact (expecially that exhaust valve location).

[Phish]

That was the issue we had with the borescope. It would only go down to the threads for the spark plugs - then the head was to big to fit (thats what she said). However, everything we could see on top of the piston looked good. We may have to take another look jsut for saftey measures.

I think Sat we are going to remove the spring and see if the valve has any issues with movement. Replace the spring if the valve checks out. We can take another look at the piston there. Hopefully we can get all this done and figured out without removing the head.