Broken Piston Rings?

[Jerry Horton]

Just tore down my 1954 Fargo motor, I believe it is an L6 228 CI.  Came out of a 3/4 ton Fargo Model FCID.  I found that all six top compression rings were broken in half.  I have seen broken rings before but never 6 of them.  Any ideas on how this happened? 

[johnsartain]

The motor may have been rebuilt before, possibly without removing the ring ridge at the top of the bore. This typically will break the top ring on every cylinder that the ridge wasn't removed. On an engine that has sat a while it is possible that rust scraped from the cylinder walls will accumulate under the ring ridge and cause the same problem in a engine that was once running. Here it depends on the general shape of the engine, depth of the ridge, amount of rust. You may not break any rings, could be one, two, or more.

[kencombs]

17 hours ago, johnsartain said:

The motor may have been rebuilt before, possibly without removing the ring ridge at the top of the bore. This typically will break the top ring on every cylinder that the ridge wasn't removed. On an engine that has sat a while it is possible that rust scraped from the cylinder walls will accumulate under the ring ridge and cause the same problem in a engine that was once running. Here it depends on the general shape of the engine, depth of the ridge, amount of rust. You may not break any rings, could be one, two, or more.

All true, also a badly worn ring groove that gets new rings can break the ring due to the twist as it changes direction. 

 

edit: overheating will also cause this.  Sort of like the lack of end gap as the overheat over-expands the rings.  But, usually there will be other signs that it has overheated.   Galling or scoring of the piston, skirt or thrust face usually.

Edited July 13, 2018 by kencombs

[Jerry Horton]

Thnaks.  The motor was bored .040 with new pistons and rings.  I will check the ring groove clearances before reinstalling.  I never thought of the ring groove being worn.  Now that is thinking outside of the box. 

[Dave72dt]

You shouldn't have a problem with ring groove wear on new pistons or a ridge with a fresh bore.  What you may have is a set of tight rings that weren''t gapped prior to installing on the piston.  Something else commonly used to start a reluctant fire up on a fresh build is the can of ether.  Too much can cause all sorts of issues. I prefer leaving the can on the shelf

Edited July 13, 2018 by Dave72dt

[Jomani]

13 hours ago, Jerry Horton said:

Thnaks.  The motor was bored .040 with new pistons and rings.  I will check the ring groove clearances before reinstalling.  I never thought of the ring groove being worn.  Now that is thinking outside of the box. 

It would seem very unlikely that all 6 cylinders would experience the same problem unless there was a mistake made during assembly. Be sure to check the ring end gap. If it is too tight, when the ring expands from the heat that metal has to have a place to go - if not, it is going to break. You would generally see scoring in the cylinders if that were the case.

[johnsartain]

20 hours ago, Dave72dt said:

You shouldn't have a problem with ring groove wear on new pistons or a ridge with a fresh bore.  What you may have is a set of tight rings that weren''t gapped prior to installing on the piston.  Something else commonly used to start a reluctant fire up on a fresh build is the can of ether.  Too much can cause all sorts of issues. I prefer leaving the can on the shelf

I remember the old GM Diesels (Converted gas Oldsmobile 350 blocks)from the 80 would have glow plug problems and people would useether to crank them. The lands between the piston groves and rings would break. That was an engine that should have never been.

 

[torqczar]

rusty    block bores.. been sitting... You know   running when parked,   15 yrs ago ...ha ha 

[Jerry Horton]

Actually it was running when I drove it into my shop to remove the motor.  However, thanks for the humor. 

[Young Ed]

6 hours ago, johnsartain said:

I remember the old GM Diesels (Converted gas Oldsmobile 350 blocks)from the 80 would have glow plug problems and people would useether to crank them. The lands between the piston groves and rings would break. That was an engine that should have never been.

 

when I was little my Grandpa had one of those. When the diesel finally died my Dad bought the car and converted it to a gas engine. My only memory of that car is being on a family vacation and being a fancy olds it had a lighter and ash tray in each door. So what does a little kid do when the button pops out and is now glowing? He touches it of course!