B-73 Restoration

[mowerman]

Was wondering if they’re still using magna flux these days ???? Every time you turn around they tell me oh wait don’t do that anymore ha ha bob

[Freightrain]

Ya, my local shop still magna fluxes parts.  U shaped electromagnet and metal dust.

[mrsmackpaul]

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

[Joey Mack]

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

[mowerman]

ok thanks for that larry....getting back to the engine,,,im surprized it wasnt making a hell of a racket,with all that damage..bob

[theakerstwo]

19 minutes ago, mowerman said:

ok thanks for that larry....getting back to the engine,,,im surprized it wasnt making a hell of a racket,with all that damage..bob

It was when ever it did it i promise you.

[theakerstwo]

Larry i still have magna flux kit and a dye kit.The magna flux will find cracks that i cant see with dye.

[mowerman]

right????????   bob

[mattb73lt]

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.

 

[Mark T]

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 .

[1961H67]

Sounds like it’s going to work out good, glad there is no block or crank damage. 

[mattb73lt]

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.

[Mark T]

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.  

[Freightrain]

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.

[Licensed to kill]

I doubt that low sulphur diesel had anything to do with the failure. In fact, these old engines may even be MORE capable of running ULSD than the new ones without an additive. Sulphur acted as a lubricant so removing it made the fuel "dry". The tolerances in the fuel system of a new style engine are MUCH tighter than the old Mechanical engines and run a MUCH higher fuel pressure. I would think that the higher pressures and tighter tolerances in todays fuel systems would suffer from lowered lubrication in the fuel more so than the old, low pressure, wide tolerance fuel systems. My preferred fuel additive is 2 stroke motor oil. It is a lubricant that is designed to burn. Anyways, that is my opinion, subject to change without notice pending compelling argument to the contrary. 

[Mark T]

7 hours ago, Licensed to kill said:

I doubt that low sulphur diesel had anything to do with the failure. In fact, these old engines may even be MORE capable of running ULSD than the new ones without an additive. Sulphur acted as a lubricant so removing it made the fuel "dry". The tolerances in the fuel system of a new style engine are MUCH tighter than the old Mechanical engines and run a MUCH higher fuel pressure. I would think that the higher pressures and tighter tolerances in todays fuel systems would suffer from lowered lubrication in the fuel more so than the old, low pressure, wide tolerance fuel systems. My preferred fuel additive is 2 stroke motor oil. It is a lubricant that is designed to burn. Anyways, that is my opinion, subject to change without notice pending compelling argument to the contrary. 

I remember the change to ULSD  . Freed up crud hiding everywhere (lol)  I'd imagine it didn't exactly help anything in an old PT pump or injectors.   Probably wasn't anything to do with what happened , but new cylinder kits, be a good idea to freshen up the fuel delivery.   a little two cycle oil....not a bad thing.  only thing that'll hurt is AOC's feelings

[Nor'Easter]

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

[mattb73lt]

Just now, 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?

Sure, give me a bit to dig it up.

[mattb73lt]

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

[Nor'Easter]

On 11/15/2022 at 10:23 AM, mattb73lt said:

 

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

Much appreciated sir!

[mattb73lt]

A little more disassembled, cleaned up and organized. I’ve got a Cummins guy coming by the shop next week to help me evaluate the block and crank to see where they stand. If the block isn’t worth putting the effort into it, I’ve got a line on another to possibly use. Been in touch  with Mahoney’s in NH about availability of the liners and  pistons. Tom says he can still get what I need to rebuild it. He’s ever so helpful and remembers me from when he helped me put the Jake on. The gentleman with the block has the whole rest of the engine along with the new parts to assemble it. But I have some big concerns regarding their current condition. A reasonable price the everything, but not if I need to redo stuff, like the heads. So we’ll see as we move forward with the evaluation.

[mattb73lt]

Happy Thanksgiving, everyone!! I hope you all have a great time with family and friends.

Yesterday was a good day. I had an old time Cummins/diesel mechanic at the shop to evaluate what I have. While I'm pretty decent when it comes to engines, this guy was just amazing and a wealth of knowledge. After a few hours of work, it would appear that the block is sound enough to move forward with the rebuild. We made several calls to the machinist that he uses and confirmed there's enough material on the top of the block to deck it and do the counterbore's. He immediately found several things he didn't like with a several parts and they'll need to be replaced. Like most of the push rods, the lower ends had been brazed at some point. He felt the block has never been completely disassembled or had a major overhaul in it's life, but someone was definitely in there.

The goal now is to completely strip the block for the machine shop and once he says it's good to go, start sourcing what's needed to reassemble it. So, it looks like this engine will live on and be about as fresh as when new when it goes back in.

[yarnall]

Sounds like pretty good news. Happy thanksgiving. 

[Joey Mack]

That sounds great..  Is that a 64 Scout in the background?  

[mattb73lt]

16 minutes ago, Joey Mack said:

That sounds great..  Is that a 64 Scout in the background?  

No, a ‘68 Kaiser-Jeep M715