Thread: push rod slipped out

Probably a collapsed lifter. Could also be a pulled rocker stud, or broken wavy washer if you have them.

it happened to one of my cars 25 years ago. It was a tight valve guide, coupled with a dry stem. Loosen it with some penetrating oil, and don't use THICK oil, it won't be able to get into a tight guide/stem clearance. Once I used thinner oil I had no problem.

Very interesting. Every time I read of someone recommending 50W oil during the summer to keep up the oil pressure, I wonder about forcing this through tight spacings. I've been running straight 30W.

run the thinnest oil you can, that will allow you to maintain 10psi/1k RPM. Start with 0-20.

Well, things are more serious than I hoped. I put the rocker back on its studs, torqued to 16 ftlbs, and went to adjust the valves. The rocker for the #2 exhaust has to be advanced in until there is hardly any thread left before it contacts the valve stem. I started the engine and heard lots of clanking from inside the case. Not a good time of the year for me to pull an engine.

Pull that rocker assembly back off and check the valve stems height with a straight edge. That one valve may be hung partially open which would explain the extra turns on your adjusting screw to get the clearance right.

when mine happened the valve was stuck almost 100% open. I had to use Kroil and a rubber mallet on the valve to get it to pop closed again. I had to keep oiling and hitting for 30 minutes to get it to free up. You can hear when it's working properly, by comparing to a normal adjacent cylinder/spring.

Interesting. I had mentally resigned myself to dropping the engine. I'll take your advice and squire and pound. Thanks a lot.

If the valves are level now, you have a cam/lifter problem. If they are not level, the problem is in the head/valve.

Sounds like a bent valve to me