Bent push rod.

Took a 25 minute flight from KJNX to KTTA to show a good friend that I had a well running airplane.   Everything was running perfect, and I was really feeling good about it all. Then two miles out, she started back firing. A few seconds later, it was a rhythmic pop in the exhaust, about once per second. I radioed that I was having engine problems and would be landing against the traffic.   Pointed the nose at 21 in a descending turn, and she quit as I was lining up. A short glide to a normal engine out landing, and I was able to coast most of the way to a parking space.
Got a taxi back to KJNX so that I could drive back with tools.  The plugs all looked good, if not indicative of running extra rich.  But when I pulled the valve cover, number two's exhaust rocker arm was cocked sideways, and the push rod was bent about 30 degrees where it exits the guide.  How does this even happen after 20 flight hours? Can I expect this to ever happen again?  Is there a way to prevent the rocker arms from rocking side to side?

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Permalink Reply by Ernest Christley on July 3, 2020 at 6:34pm

Permalink Reply by Ernest Christley on July 3, 2020 at 6:36pm
You have to zoom in to the picture to see how the rod is bent at the bottom of the rocker arm.
Permalink Reply by Wayne Woloshin on July 4, 2020 at 7:43am

Sorry to hear about your pucker situation,but if you want feedback input , it would be helpful to know what engine you are talking about and specifications.

Permalink Reply by Ernest Christley on July 4, 2020 at 8:23am

Well, I did post this in the Corvair forum.  Would it being a 3100cc vs 2700cc make a difference in a rod getting bent?

Permalink Reply by William Dominguez on July 4, 2020 at 10:32am

You don't seem to have valve rotators in your exhaust valves. Who did your cylinder heads job?

Permalink Reply by Ernest Christley on July 4, 2020 at 3:49pm

I bought the engine second hand.  I can't find any references to Corvairs using rotators.

Permalink Reply by William Dominguez on July 4, 2020 at 6:08pm

Almost all Corvair fly engines have exhaust valve rotators. Go to flycorvair.net and search for "rotators", you'll see plenty of references, including the video bellow;

youtube.com/watch?v=zFTQdu2XBPY

I'll second Dave suggestion to call WW or DW, (does not mean to shut down this conversation). I see another issues in your picture, the top of the push-rods tubes seems to stand out more than normal, compare yours to the video, if that the case, it could be the root of your problem.

Permalink Reply by William Dominguez on July 4, 2020 at 6:20pm

Just noticed you are already in contact with DW in CorvAircraft. Just make sure, if you haven't already, that he sees the pictures of your head above.

Permalink Reply by Dave Gardea on July 4, 2020 at 2:31pm

Hi Ernest,

Congrats on your piloting skills in getting yourself and your passenger safely on the ground. I would highly recommend you give William Wynne a call at 904.806.8143. He's openly invited that Corvair builders call or text him as needed. He'd be most qualified to help you diagnose what happened with the rocker arm and push rod. Otherwise, you might receive some less helpful advice from us arm chair experts who may or may not have Corvair experience.

Regards,

Dave

Permalink Reply by Ernest Christley on July 4, 2020 at 3:52pm

A forum is a place for "arm chair experts", and I've seen Wynne be wrong about enough stuff to consider him just another "arm chair expert".  Please don't try to shut down our conversation if you don't have anything to offer.

Permalink Reply by Dave Gardea on July 4, 2020 at 4:00pm

Ernest, wasn’t trying to shut down the conversation at all .. merely offering my own arm chair advice as I had built my own Corvair and have been flying it for over 500 hours. Good luck and hope you resolve your engine problem.

Regards,

Dave

Permalink Reply by Ernest Christley on July 4, 2020 at 4:07pm

Update:  I suffered the heat to work on her out on the ramp today.  When I pulled the rocker arm, the push rod was in two pieces.  I'll try to get a good picture of what I think looks like metal fatigue.  I was probably a defective push rod that just took 20hrs to fail.

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