Broken Rings, piston and pushrods

[66airVair]

Hi all,
I recently tore down my 66 140, due to massive oil leaks, and blowing smoke. Overall bearing clearances and most everything internal looks great, the Cylinders are smooth and not gouged, cam and crank look great, BUT I ended up finding three broken Top compression rings, all on one side which is interesting, a broken piston, as you can see it broke at the oil ring, and I found two bent pushrods. Even with all of these issues, the car still ran! LOL!
Before this happened the car ran like a champ, the timing was dead on at 18 degrees, and it never pinged, that I'm aware of (yes I run 93 octane in it).
I did have an event last summer where the car overheated but for no apparent reason. It was on a long highway drive where the RPM's were up (3500) for about 45 min. At the time I was thinking maybe it ran lean but then it never happened again. Recently, during cold starts, the engine would tap real loud, and after a few months it eventually started blowing a lot of smoke. That's why I ended up tearing it down this past week. Maybe that over heating event triggered all this?

I wanted some expert opinions on what I found, and what I should look out for during and after my rebuild.
I purchased the car a year ago, so this could have been brewing long before I got the car.
I just ordered new cylinders, pistons, rings and gaskets from California Corvairs and would rather not have this happen again!

What do you think could have caused this to happen? or what is the likely culprit? Pictures attached

[davemotohead]

Its because the stock GM pistons suck and break after about 60-80 thousand miles, more than likely some piston bits got sucked into the other cylinders causing the rings to break? If I seen it once I seen it a 1000 times!

[66airVair]

Wow, ok! Thanks for the response! I watch your videos on YouTube!

[jimbrandberg]

I usually remove the rod/cylinder/piston as an assembly and then pull the rod/piston out of the bottom of the cylinder.
When installing I knock the piston in from the top while holding the cylinder in the crook of my arm like a baby. This direction doesn't work if there's a carbon ridge.
I have a wonderful ring compressor that tightens a ceramic piece with a hose clamp. Ray Sedman did a group buy I suppose 20 years ago. Much better than the slipping blue sheet metal thing I had previously. The ceramic one has a range and would not work on 3 9/16 or maybe it was 3 5/8.

I had an engine last year that still ran on 5 cylinders. When I took the head off the notch in the pisston top that's supposed to point to the front of the car was pointing down. The top half of the piston was happily resting in the top of the cylinder while the bottom half came and went as usual. It hadn't done the head any good.

I don't know about your pushrod issues. What's up with that?

Jim Brandberg
Isanti, MN
CorvairRepair.com

[chris]

I'm with Dave on that piston. It would be just like a valve seat dropping and pieces getting sucked into the other chambers.

[American Mel]

Post a picture of the Nova!

[kmart356]

I purchased the car a year ago, so this could have been brewing long before I got the car.

My bet is that the previous owner was having mucho fun with that 140 while he had it (that's what they are designed for i suppose). It has been slowly getting worse and now you have uncovered the damage. Dave already pointed out that cast pistons fail and bent push rods can come from high performance driving. Get some good (stronger) pushrods to go with your new cylinders, pistons, rings and gaskets. Make sure those heads are still strong (valve seats) and build that 140 back to its former glory.

Examples used as reference:

Engine ran "good" but was burning oil - found this.
.

Scorched Piston_2 small.jpg (22.2 KiB) Viewed 204 times

Engine ran "ok" but kept getting worse. Very low compression on this cylinder.
.

broken piston small.jpg (18.43 KiB) Viewed 203 times

[Brizo]

66airvair, \Maybe you used 93 octane gas but I bet the previous owner didnt. Broken rings, broken lands, and excessive ring to groove clearance are all typical damage caused by detonation.

[66airVair]

Here ya go American Mel
68 nova
66 corvair
Thanks for all the replies guys

[American Mel]

Noice!