Piston Rings Worn Out, Time for a Rebuild

[daytonatrbo]

I said it already: both sides are tapered!

View attachment 606353
(drawing based on TM 9-2815-210-35, fig. 286 (Sep1964))

Well that seems to answer the 2dots on top question.

 

[74M35A2]

We just bought two of the 30k fuel fired cab/cargo heater kits. Wild said we should install them next to each other in the bed facing rearward so it looks like an F-15 firing up (I thought that was a fabulous idea), but it probably won't propel the truck forward. So, it looks like we will have to reassemble the engine and "hope" this doesn't happen again. Would be nice to know why it didn't seal up the first time. No broken or melted parts on disassembly, and everything was new and installed correctly, 2,000 miles or less on it. Ugh...

 

[Wildchild467]

We just bought two of the 30k fuel fired cab/cargo heater kits. Wild said we should install them next to each other in the bed facing rearward so it looks like an F-15 firing up (I thought that was a fabulous idea), but it probably won't propel the truck forward. So, it looks like we will have to reassemble the engine and "hope" this doesn't happen again. Would be nice to know why it didn't seal up the first time. No broken or melted parts on disassembly, and everything was new and installed correctly, 2,000 miles or less on it. Ugh...

Yes, very frustrating. Surprisingly, I'm holding myself together with this project.

 

[74M35A2]

Everybody is saying to load it up right out of the gate. Want to chain it to my 925 and I'll hold my brake pedal half way down? That should make it fart...

 

[Wildchild467]

Rip the sternum right out of the truck.

 

[doghead]

Middle of Winter Blues...

"I think I'll pull my pistons out, just to have a look"...

FWIW, with no compression, It does not surprise me to see so much carbon on that piston.

I'd like to hear Will Wagner's thoughts on this issue. Will...?

 

[daytonatrbo]

Rip the sternum right out of the truck.

Find a really big tree

Put it in 6-Lo
Pull up, bumper to the tree
Use the hand throttle and dig 6 nice holes
Come back after a coffee break and see what broke.

 

[DavidWymore]

Connected or up against an immovable object, my LDS will dig 6 holes in low with no throttle input. Has some pretty serious grunt.

 

[daytonatrbo]

Connected or up against an immovable object, my LDS will dig 6 holes in low with no throttle input. Has some pretty serious grunt.

In the grass, mine will idle the wheels around too, but you don't want to idle on engine through breakin.

 

[o1951]

. I have never seen 95% leak down rate with new rings intact. Starting to look like they just did not seat correctly for whatever reason. His plan is to ball hone the new cylinders, clean up his previous pistons which have one additional ring on them, re-ring and install those pistons, and then attempt a break in per procedure, though that will be difficult because procedure uses dyno loading values of hp and RPM (15hp @ 1000rpm for the first hour or whatever). All parts are ordered or have been received already. He will break it in on 100% diesel fuel, and if leak values stay proper, then later decide whether to try WMO oil again, well after the rings have broken in. Or, maybe just run WMO from known sources and not the local city recycle center.

Good!
For diesels, I like 4 ring pistons with long skirts. (not on women tho)

Around the time those trucks were built, and before, a lot of engines came with "break in oil" which was supposed to be changed in 500 miles or such. Break in oil was really just crappy oil that had poor wear characteristics. Helped everything wear in and seat fast.

Now, I am thinking - today's oils are really good, with excellent anti friction and wear properties. Much better than when truck was built. Maybe you should use lower quality oil for initial run. Look up in TM's what the lowest acceptable grade of oil was, and buy the closest to it you can find for initial run. Maybe something similar to the old CA, CB or CC oil would be better for break in.

 

[gimpyrobb]

If you guys think it would help, I have a 5gal can of 30wt oil. Not sure on age, but I know its mil surp!

 

[74M35A2]

Good!
For diesels, I like 4 ring pistons with long skirts. (not on women tho)

Around the time those trucks were built, and before, a lot of engines came with "break in oil" which was supposed to be changed in 500 miles or such. Break in oil was really just crappy oil that had poor wear characteristics. Helped everything wear in and seat fast.

Now, I am thinking - today's oils are really good, with excellent anti friction and wear properties. Much better than when truck was built. Maybe you should use lower quality oil for initial run. Look up in TM's what the lowest acceptable grade of oil was, and buy the closest to it you can find for initial run. Maybe something similar to the old CA, CB or CC oil would be better for break in.

That is a very interesting perspective I had not considered. I know they specify not to run synthetic for that specific reason, but we didn't. Also, todays oil do not have the zinc levels in them anymore like they used to. Still an interesting point though. Good thinking out of the box.

 

[JasonS]

Good!
For diesels, I like 4 ring pistons with long skirts. (not on women tho)

Around the time those trucks were built, and before, a lot of engines came with "break in oil" which was supposed to be changed in 500 miles or such. Break in oil was really just crappy oil that had poor wear characteristics. Helped everything wear in and seat fast.

Now, I am thinking - today's oils are really good, with excellent anti friction and wear properties. Much better than when truck was built. Maybe you should use lower quality oil for initial run. Look up in TM's what the lowest acceptable grade of oil was, and buy the closest to it you can find for initial run. Maybe something similar to the old CA, CB or CC oil would be better for break in.

Modern tractors still use break in oil. At least the green ones do.

 

[JasonS]

https://m.jdparts.deere.com/partsmkt/document/english/pmac/5452_fb_BreakInOil.htm

 

[rustystud]

View attachment Scan0063.pdfView attachment Scan0062.pdfView attachment Scan0064.pdfView attachment Scan0065.pdf

LOL. I know you love to argue EVERYTHING. You are correct that they will stop rotating if the cylinder becomes out of round. Otherwise, they will normally rotate. This has been studied quite a bit by engineers and published; read up. Let me know if you need some hand-holding and I'll even do the search for you.

Just because I do like to learn or in this case "relearn" I looked in one of my old engine manuals and found this. Yes your right Jason, this time ! I think your still sore from the last "ass wooping" I gave you !
About who likes to argue more you have got to be kinding ! Your like the pot calling the kettle black !
I will hold your hand though as long as it's warm !

As far as why there is a taper or bevel on the rings, like I said earlier. It is to provide pressure against the cylinder walls.

 

[74M35A2]

That manual is not that old, pics are in color.

 

[rustystud]

That manual is not that old, pics are in color.

You do realize color pictures have been around since the civil war ? They just weren't used much because of cost. How old do you think I am anyway ?!?!?
My great-grandfather fought in the civil war not me !

 

[o1951]

Wildchild, I am very careful with what I put in or feed my engines. If you choose to go that route, the John Deere diesel break in oil looks interesting. Says made for new and old tractors, to help rings seat without wearing cams or other parts. I like something made specifically for that by a reputable manufacturer.

 

[74M35A2]

You do realize color pictures have been around since the civil war ? They just weren't used much because of cost. How old do you think I am anyway ?!?!?My great-grandfather fought in the civil war not me !

I don't know, you don't look that young in your avatar pic...

 

[rustystud]

I don't know, you don't look that young in your avatar pic...

I might look old but my heart is young ! Though last week I scared the crap out of myself when I went to the bathroom after waking up and looked in the mirror. I saw my father looking at me ! and he's been dead for decades ! I realized of course it wasn't a ghost I was seeing but myself, but for a split second I thought I had seen a ghost !