I'll tell you my story. For the people who don't know, i'm from chile and i've a catera (an Opel Omega really). A month ago i had a problem with the heater valve. It was leaking. So i send the car to the dealership. They said Ok, we will fix it, but we must measure the cylinders compression. I wasn't worry, because the car hadn't power or economy problems, but the results weren't good. 2 cylinders had very little compression (about 50-60 psi) and the others were low, but not so bad (arround 180psi, i think). Then, they must take off the cylinder head. The reason for the very low compression in the 2 cylinders was an old head gasket, and the low compression in the others cylinders were by a sealing problem of the valves, they wear out. So, i must replace the valves. The intake valves cost me here in chile about 15 dollars each, which isn't so bad, but the exhaust valves....120 dollars each!!!! the reason: they are filled with sodium.
So they send the head to an engine repairshop, to make a measurment. I could save the exaust valves!!! and the head was ok.
Now they're finishing the job, i hope it last.

I'll informe you, when it is ready

omg. I can't beleive it. Your story is almost exactly like mine except for the dealership part. I'm a mechanic and found on my 97 catera a loud knocking sound wich came on all of a sudden. I did a compression test and found #5 & 3 cyl. was about 60 psi and #1 was 210 psi. So I removed the head and found a peice of head gasket(just a little peice of the metal part) in #5 and #3 cyl. I guess it came unlodged when my wife got rearended. made a helluva racket. Bent all four intake valves in those cyl. Going to replace both heads since I'm getting a good deal on rebuilt ones(free). Just wanted to say my piece. What are the odds of that happening?

hmm