My flattie ate an oil ring

[woodymerc]

Hello all. This is my first post. I am Mark and I have a 31 Ford sedan with a 51 Ford flattie in it. I just did my first oil change on a fresh, 500 miles, motor and found and entire oil ring, in pieces in the pan. All of my parts came from Macs in Lockport and the engine was assembled by my regular machine shop which has lots of flattie experience. Has anyone else ever had this happen. I have been a mechanic for 45 years and have lots of engine experience and have never seen this before. Thanks to all who may be able to enlighten me.

[petehoovie]

How were you able to find an entire oil ring in the pan by just changing the oil? Did the pieces flow out with the oil? Is the engine running OK?....

[cmbrucew]

Wood
If you found it in the pan there should find other stuff in there with the entire ring. Maybe one of your rods now has a skirt. Good luck
Bruce

[Talkwrench]

What brand of rings did they sell you?

[BLACKNRED]

How would you find an entire oil ring.
Oil rings are in 3 pieces, 2 thin high tensile rings and a castellated ring.
The only way would by the bottom of your piston has disintegrated.
If this has happened, you need to pull the engine down.

[woodymerc]

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Thank you everyone for taking the time to reply. On my first oil change I always run a magnet into the pan to check for filings. I also run a quart of oil through a cheese cloth strainer to for the same reason. I found a piece of the corrugated part of the ring and then fished out 3 more pieces. The scrapers are still intact. I pulled the pan and piston and my machine shop has reordered parts and will make it right. Iwould just like to know if this has ever happened to anyone else? All the parts came from Macs so I am not sure who manufactured them. This is the first time I have had any issue with their engine parts though.

[JSeery]

Be interesting to see how a ring can come apart and get past the piston/cylinder wall without a considerable amount of damage to both. Keep us posted.

[woodymerc]

The ring apparently cam through the oil drain slot on the inside of the piston, by the top of the rod. It is a pretty sizable slot. No other damage to the piston or other parts that are obvious

[Seth Swoboda]

Don't buy engine components from MAC's, or anything else. Our pals in China make their stuff. There are more reputable suppliers and your machine shop should know who they are. I've always had good luck with pistons and rings from Egge.

[corvette8n]

Found pieces of rings when I drained the oil on my shoebox in 1964, it was my first car, two Pistons had holes in them one was missing about a sixth of the outside edge. That ended up being my first rebuild.

[40 Deluxe]

Originally Posted by woodymerc

The ring apparently cam through the oil drain slot on the inside of the piston, by the top of the rod. It is a pretty sizable slot. No other damage to the piston or other parts that are obvious

This is really strange! Could you show us some pictures? Is the drainback slot big enough for the expander to fit through? If the expander ends were butted together over a slot instead of the solid part of the groove, one end of the expander may have popped into the slot, perhaps during assembly. Of course, rings rotate in their grooves, so this may have happened after running awhile.

[woodymerc]

Sorry no pics, not really much to see actually. I am hoping it was a faulty ring, all of the others are fine. The bores are all good and everything else looks normal. The oil return slots are big enough to fit a ring through but we have not seen one do it before. There is so little clearance in the bore that it should not ever be able to wiggle out. Perhaps the end of the expander did get pushed in when the rings were compressed during installation. We will reassemble with new rings and see what happens. I am guessing that no one else has ever seen this happen so I think it is an unusual event. Hope it is my last.

[Capt Kirk]

"I found a piece of the corrugated part of the ring and then fished out 3 more pieces. The scrapers are still intact."

I don't know how big the drain slots are on a flathead piston but I can envision that if the "corrugated part" had broken into 4 pieces during normal operation and the slots are the full width of the ring groove, that they could fall into the pan with little to no damage. The hard part for me to envision is that intact scrapers (which are trying to expand against the cylinder) made it through the drain slots...and all with no damage to the piston or cylinder. Hmmm

[40cpe]

I'm thinking that he meant that the scrapers are still intact on the piston.

[Seth Swoboda]

I would have liked to seen photos but thats ok. I always like to learn from these incidents. My flattie usually just eats my money.

[rotorwrench]

I've seen where folks felt the expander was too tight at installation so they trim it down a bit. Big mistake! It's supposed to be tight.

[woodymerc]

Just to clarify for the Capt.The scrapers were still in the grove when I pulled the piston out. No damage to anything else that I could see. If you have a piston kicking around have a look at it. The drain slot is fairly long and full width of the ring, at least on a replacement piston. I probably could have kept running the motor like that but eventually something would have broken I am sure. New TRW rings will be here tomorrow and hopefully the engine will be running by Saturday morning. We will be very careful with ring alignment on assembly and I hope this is the end of my problems.

[Mart]

If it is a 4 ring piston, you might consider leaving the bottom ring out. It may help, can't say from here.

Mart.

[Ronnie]

Where do you get TRW rings?

[40 Deluxe]

Originally Posted by woodymerc

Just to clarify for the Capt.The scrapers were still in the grove when I pulled the piston out. No damage to anything else that I could see. If you have a piston kicking around have a look at it. The drain slot is fairly long and full width of the ring, at least on a replacement piston. I probably could have kept running the motor like that but eventually something would have broken I am sure. New TRW rings will be here tomorrow and hopefully the engine will be running by Saturday morning. We will be very careful with ring alignment on assembly and I hope this is the end of my problems.

Your replacement pistons could be old stock, made back in the day when oil rings were the primitive one piece design that could not fall through the drain slot. Seems like the slots in new pistons that are designed for the three piece rings have a 'lip' in the slots to hold the expanders in place.

P.S. Just went out to the garage and looked at an aftermarket 4 ring piston (age unknown). It has a lip in the upper oil ring groove such that an expander would not fit through it. The 4th (bottom) groove just has small holes for oil return.