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B-73 Restoration


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I would be guessing you blokes are right about the rolled O ring

 

That been said the motor was probably rebuilt by a normal bloke like most of us and didn't even realise

I doubt commercial truck owner would of rebuilt this for commercial use

So we shouldn't be to hard on who ever rebuilt it, I'm thinking it was done with the best of intentions 

I wonder if the motor sitting  for so long got rust in a groove of the twisted O ring and the rust cut thru the O ring with heating and cooling 

If this had been im continual use I wonder if it would of happened at all ?

Paul

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I think what happens is when the engine runs HOT, the rolled o-ring can form a bulge in the thin liner at the spot where the o=ring is rolled, therefore, causing the cylinder bore to be reduced,,  then,,,,  well the piston rings dont fit good inside an egg shaped cylinder, and then the skirt grinds the shaving made by the rings, and well...    you get what was shown in the picture...    at least that is my take on it..  jojo

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Yup, manga flux is still very common, dye penetrant, too. I think I was heading for trouble with these sleeve seals, one way or another. I think they were damaged during installation and not rolled as #4 & #5 bores and pistons were clean. I borrowed the sleeve puller from Matt Pfahl and we were having a discussion on older Cummins engines. He has a tuned (400 HP) Cummins in his crew cab Superliner. He had sleeve issues on it during a vacation trip. We were both of the opinion of tearing them down to at least pull the sleeve and reseal them to check for corrosion. Both our engines had sat for some time before going back into use.

As for noise, yeah it was making a racket. That was why I thought I spun a bearing. What I was hearing though, was piston slap. When tearing it down, I was turning it over by hand and #6 would cant way over as it came up the bore. Doing so because there was no lower bore to control it.

 

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Rolled O ring.... rust jacked O ring.... same effect. Gotta remember, these engines were never 55 + years old before. Even an 855 is getting a little long in the tooth. What did the inside of the liners look like ?  Something was happening to that engine before you ever laid eyes on it, someone already put one piston in it at least .

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6 minutes ago, Mark T said:

Rolled O ring.... rust jacked O ring.... same effect. Gotta remember, these engines were never 55 + years old before. Even an 855 is getting a little long in the tooth. What did the inside of the liners look like ?  Something was happening to that engine before you ever laid eyes on it, someone already put one piston in it at least .

They were all really clean, but #6. No scuffing on the bores or skirts. I agree with the age issue. If ever faced with this again, I would open it up and check them and replace all the seals just to be sure. It'll get done now. I've been sourcing the parts, but need to tear it down some more to get a full list of parts needed. I do have a Cummins contact that I hopefully get to come to the shop to help in the evaluation and rebuilding efforts.

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Good news. Cylinder bores that have a polished look , almost like chrome is an indication of wash down.  In my opinion, you had a couple issues with that engine . Liners, and fuel. Cam and it's followers are the metering and timing, and it's easy enough to adjust excess play out in the overhead. Problem is it'll be out of time and it may vary from cylinder to cylinder.   I have my doubts that engine ever ran on ultra low sulfur fuel too.  

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On 11/13/2022 at 8:28 AM, Mark T said:

  I have my doubts that engine ever ran on ultra low sulfur fuel too.  

I keep Power Service in my truck and give it a dose at every fill up.  Anything is better then nothing for these old engines.

IMG-20180116-202556-655.jpg

Larry

1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"

 

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24 minutes ago, mattb73lt said:

Sure, give me a bit to dig it up.

 

25 minutes ago, Nor'Easter said:

Matt, would you mind sharing the insert part number you used in the exhaust stack? I believe it was a 5" stack?

Purchased from Iowa80, Quiet Muffler insert for 5” stack, P/N 185086

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