ULTM8Z

Suppose a valve was hanging up during engine operation? Is there any possibility that it would pass a leakdown and compression test? That is, it seats properly with the engine off, but hangs up with the engine running?

I ran these two tests on my engine and it passed with flying colors. But with my misfire, I'm wondering if there could still be a valve problem...

GMTech

Bent or Burnt valves will, broken (or weak) valve springs will not, niether will a sticking guide.