old Henry's engine
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Old Henry
Well-known member
I'm updating status on my original thread here: http://www.fordbarn.com/forum/showthread.php?t=104413
Just posted this report there:
Doc Roger took the pan off last night and found that the piston pin was broken and the connecting rod was bent in addition to the piston being broken into pieces as shown in my picture. He didn't see any sign of something coming into the cylinder through the intake that would have jammed the piston to break it. The connecting rod was still connected to the crank shaft just fine. My guess had been that it had come off and caused the problem but not so. He couldn't think of anything that would have caused the piston or piston pin to break as it did (not knowing which went first). There is damage to the cylinder wall that will need a sleeve to repair. He's going to check out all of the other cylinders and pistons to see if anything else needs work and let me know. His preliminary examination of the other cylinders from underneath didn't reveal any wear on them at all. I was glad to hear that after just 30,000 miles.
This may be just a fluke problem that we'll never know the cause of and not be able to do anything more than I already did to prevent it from happening again.
Just posted this report there:
Doc Roger took the pan off last night and found that the piston pin was broken and the connecting rod was bent in addition to the piston being broken into pieces as shown in my picture. He didn't see any sign of something coming into the cylinder through the intake that would have jammed the piston to break it. The connecting rod was still connected to the crank shaft just fine. My guess had been that it had come off and caused the problem but not so. He couldn't think of anything that would have caused the piston or piston pin to break as it did (not knowing which went first). There is damage to the cylinder wall that will need a sleeve to repair. He's going to check out all of the other cylinders and pistons to see if anything else needs work and let me know. His preliminary examination of the other cylinders from underneath didn't reveal any wear on them at all. I was glad to hear that after just 30,000 miles.
This may be just a fluke problem that we'll never know the cause of and not be able to do anything more than I already did to prevent it from happening again.
Old Henry
Well-known member
Old Doc Roger is 30 miles away and I have a hard time cornering him at his shop to get pictures. Hope to get in there when I'm in his town on Monday to get some pictures and his assessment of anything else he thinks needs doing. I'm going to talk to him seriously about the quality of parts he put in when he rebuilt the engine 30,000 miles ago and see if there isn't any better we can use this time around. (I will certainly bring up all of the suggestions I've had here, i.e. Egge or Ross pistons new, not NOS, etc.)
I've upped my goal for our 40th anniversary next month to Glacier/Waterton National Peace Park on the Montana/Alberta border to stay in the Prince of Wales Hotel on Waterton Lake that's been on our bucket list since we first saw it a few months after we were married. (Wife didn't think the top of Mt. Evans seemed very romantic for this occasion.)
And "Going to the Sun Road" in Glacier National Park.
Next time you see these pictures Old Henry is going to be in them. It's 765 miles one way from my house to there. A bit too far for AAA to tow us home so I hope Doc will make the engine reliable enough for the trip. It'll be our longest trip so far - probably over 2,000 miles round trip. I know others have done longer but I'm just "baby stepping" up to those long distances.
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oldford2
Well-known member
Professor,
I can't wait to see the pictures of your anniversary trip. We took our 46 to Nova Scotia (750 miles one way) and it was a breeze. Have the "Doc" throw in a Mitchell O/D while it is in his shop. If you were closer I would loan you a fresh 8ba rebuild just on the test stand.
John
I can't wait to see the pictures of your anniversary trip. We took our 46 to Nova Scotia (750 miles one way) and it was a breeze. Have the "Doc" throw in a Mitchell O/D while it is in his shop. If you were closer I would loan you a fresh 8ba rebuild just on the test stand.
John
Old Henry
Well-known member
Had a phone message today from the Doc who said the block is apart and at the machininst for machining (whaterver that is). I don't know if he's doing more than just the cylinder that needed sleeved or not. Am meeting with him at his shop on Monday to discuss. Hopefully he'll figure out a better way to do things than last time so's I'll get more than 30,000 miles on his next job.
33cabriolet
Senior Member
It looked like you had NOS pistons without the steel reinforcing band. John
Old Henry
Well-known member
Here's the rest of the piston that came apart.
And here's the bent connecting rod.
And here's what I think the evidence indicates happened.
On one side of the connecting rod the piston pin is flush with the edge of it and undamaged.
The other side is sticking out too far and broken off with a lot still stuck in the piston pin socket.
So, I'm thinking that the pin may have slid to one side and out of the piston hole causing the piston to break and the rod to bend.
Unfortunately, Doc Rogers could not get a piston to match the other 7 he put in 3½ years ago. He had a piston that he could make work but I decided to get all new pistons that hopefully were better and would all match. I've got a set of Sealed Power pistons coming from Summit Racing that should be here this weekend.
Doc is having the two clutch surfaces refinished and the clutch disc replaced. He had the block in the hot tank for two days for whatever good that will do and has had the damaged piston sleeved and bored to match the rest. So, hopefully he'll have the block and clutch back and I'll have the pistons to give him to start putting it all back together next week.
I still have hopes of having the car in the local car show on June 15th and heading to Glacier/Waterton National Park the Monday after. It's looking like we will probably make it.
And here's the bent connecting rod.
And here's what I think the evidence indicates happened.
On one side of the connecting rod the piston pin is flush with the edge of it and undamaged.
The other side is sticking out too far and broken off with a lot still stuck in the piston pin socket.
So, I'm thinking that the pin may have slid to one side and out of the piston hole causing the piston to break and the rod to bend.
Unfortunately, Doc Rogers could not get a piston to match the other 7 he put in 3½ years ago. He had a piston that he could make work but I decided to get all new pistons that hopefully were better and would all match. I've got a set of Sealed Power pistons coming from Summit Racing that should be here this weekend.
Doc is having the two clutch surfaces refinished and the clutch disc replaced. He had the block in the hot tank for two days for whatever good that will do and has had the damaged piston sleeved and bored to match the rest. So, hopefully he'll have the block and clutch back and I'll have the pistons to give him to start putting it all back together next week.
I still have hopes of having the car in the local car show on June 15th and heading to Glacier/Waterton National Park the Monday after. It's looking like we will probably make it.
rotorwrench
Well-known member
Pins can't go out any farther than the cylinder wall but they can start to score the hell out of the wall where the clip comes out. A con rod that has a bit of bend in it that goes undetected at overhaul can cause the wrist pin to want to push out to one side in operation. It's very important to have the rods checked every way you can before consideration for use.
It sort of looks like the piston cracked in the 3rd ring groove and eventually broke part of the skirt off allowing the con rod & pin to go haywire inside the cylinder. Only one side broke loose so the wrist pin was only holding on one side with a very unequal load on it. There are usually reliefs in the oil control ring grooves to allow oil to get out of the groove. If the piston had a casting flaw or there was some sharp machining in the groove that caused a stress riser, then that could have been the cause of the failure.
Since photos don't always tell the whole story, I couldn't be certain but that's what it looks like to my eyes & way of thinking.
It sort of looks like the piston cracked in the 3rd ring groove and eventually broke part of the skirt off allowing the con rod & pin to go haywire inside the cylinder. Only one side broke loose so the wrist pin was only holding on one side with a very unequal load on it. There are usually reliefs in the oil control ring grooves to allow oil to get out of the groove. If the piston had a casting flaw or there was some sharp machining in the groove that caused a stress riser, then that could have been the cause of the failure.
Since photos don't always tell the whole story, I couldn't be certain but that's what it looks like to my eyes & way of thinking.
Tom Walker
Senior Member
Prof Henry, can you see any sign that the piston pin has seized in its bore in the piston, and in the small end of rod?
Its hard to tell in the photos, but any bluing of the pin, bluing on small end of rod or galling in the pin bore could show this. If the pin seizes in the piston and small end of rod, it could apply the kind of force to the piston that will break it (amongst other damage!).
If it has seized, it could be pin clearance too small or of lack of lubrication. Check other pistons for signs of heat/tightness in pin.
Just a thought, Tom.
Its hard to tell in the photos, but any bluing of the pin, bluing on small end of rod or galling in the pin bore could show this. If the pin seizes in the piston and small end of rod, it could apply the kind of force to the piston that will break it (amongst other damage!).
If it has seized, it could be pin clearance too small or of lack of lubrication. Check other pistons for signs of heat/tightness in pin.
Just a thought, Tom.
Old Henry
Well-known member
The pin is definitely stuck in the rod and can't be moved. Don't see any sign of heat seizing but that could well have been it. Probably a good thing we're replacing all pistons, pins, and rings.
Roger/Sacramento
Senior Member
I wonder if you are reboring the cylinders. I have always known to not bore until the pistons arrive to make sure the proper clearance between piston and cylinder is achieved.
Old Henry
Well-known member
I wonder if you are reboring the cylinders. I have always known to not bore until the pistons arrive to make sure the proper clearance between piston and cylinder is achieved.
As far as I know the only boring is the sleeve in the damaged piston. All of the other pistons were fine - just bored .030" over 30,000 miles ago.
Tom Walker
Senior Member
I've got to careful how to put this, but if the same guy's doing the work, you might want to talk around the subject of pin fit. Would hate for you to have the same prob with all that nice new kit....
uncle max
Well-known member
Machinist 101... Couldn't agree more!
I wonder if you are reboring the cylinders. I have always known to not bore until the pistons arrive to make sure the proper clearance between piston and cylinder is achieved.
Old Henry
Well-known member
I was kinda surprised too - that he didn't know what kind of pistons he put in 3½ years ago or where to get one to match. When he showed me at that time the pistons he was going to put in compared to my old ones I was a bit uneasy and maybe now it looks like I may have had good reason to be. So, I'm glad we're getting a well known brand that's been made for many years and have a good reputation so that hopefully the chances of this kind of problem are reduced.
rotorwrench
Well-known member
There were some pistons sold by Speedway (three ring types in sizes less than .125" oversize) that were discontinued. I figured they must have had some problems with those or they would still be available. Egge makes the three ring but only in .125" oversize or larger. Sealed Power are 4-ring but they are a solid design. I've heard of no problems with them.