CM2250 764K, rod and main update!
03-25-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #10
RE: CM2250 764K, rod and main update!
From reading other people's posts they say to check the size of the bearing you pull out to be sure you are putting the right size back in.


User's Signature: 2015 Kenworth T660
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03-25-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #11
RE: CM2250 764K, rod and main update!
(03-25-2020 )Mattman Wrote:  From reading other people's posts they say to check the size of the bearing you pull out to be sure you are putting the right size back in.

yes, you have to verify the part#'s as they come out (+ measure them) to ensure cummins did not switch sizes on it mid-engine or some other thing during manufacture.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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03-26-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #12
RE: CM2250 764K, rod and main update!
Only about $1700 for those parts? Why would anyone skip out on a preventative measure like that where the relative cost is so low? Hell, I think my OEM CAC costs more than all those parts!


User's Signature: "So long and thanks for all the fish"
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03-26-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #13
RE: CM2250 764K, rod and main update!
Update: I only got the first two mains done today. I was waiting on my wife to get back with parts, then it just takes awhile doing it all by yourself. A lot of ins and outs back and forth under the truck.
So I am glad I decided to go ahead and do them. There was no visible soot in the motor until I dropped the first main cap. Needless to say it was not as clean as Rawzes! It took about 45min to carefully clean each cap. The lower bearing surfaces on both were showing wear. The crank journals still look beautiful, so I guess it was the right time!

Also refinishing the oil pan while it’s off with POR 15, and then Massey Ferguson Red, (it’s $4 a can instead of $11 for Cummins and it matches almost perfectly!


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User's Signature: Anti-seize EVERYTHING, Except injectors...Use Petroleum Jelly!!!
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03-26-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #14
RE: CM2250 764K, rod and main update!
It was time...
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 Thanks given by: tree98 , JMBT , dhirocz
03-26-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #15
RE: CM2250 764K, rod and main update!
yeah, looking that at upper rod cap bearing, it was definitely getting due.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: JMBT
03-30-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #16
RE: CM2250 764K, rod and main update!
Update: so at the end of today I have finished all the rods, mains, and piston cooling nozzles. I am very glad I went ahead and did this service, because I did find wear on all the bearing surfaces, but the crank journals all still looked great.
I still have to install the new oil pump, and finish putting things back together. I thought I would share some things I have learned, things I am a bit concerned about at this point and some pitfalls I have found so others might be able to avoid them.

1. This is a very, very, very difficult job to do by yourself without a helper. You will literally be making hundreds of trips back and forth from under your truck, sometimes while holding freshly lubed bearings shells trying not to touch anything and get them dirty. Going back and forth to bar the motor multiple times to try and get it in the right position. Just a word of advise... enlist a helper before you start this job.

2. I am a little worried, because although I tried as hard as I could to keep it from happening, I noticed as I slid in the upper bearings some lube, (not a lot), but some would work it’s way through the hole in the bearing, therefor getting in the upper bearing saddle area that is supposed to be kept clean and dry. Will this cause a problem? IDK, but I will soon find out.

3. I did all my mains 1 at a time, as the manual suggests if you are not removing the crank. I did them completely start to finish. This was my mistake. DO NOT do the final torque, the 180 degree part on any of the mains until you have replaced them all. My thought was since I was doing 1 at a time I could do each position start to finish in what ever order I chose since I was only disturbing 1 at a time. However when I got to my last position which ended up being #4 the upper bearing would not roll in. I had to back off all the other bolts to get it to slide in. Then re-torque in the order specified in the manual.

4. Removing the rod caps was a lot tougher then the mains. I feel Cummins really dropped the ball in the manual on this one. The manual says only “beat on the loosened bolts with a rubber hammer to loosen the caps” This does absolutely nothing other then gall the threads on the rod cap screws. (And I bet those bastards know this) anyway after beating the hell out of the first screws I tried using a large pair of channel locks with the jaws taped up with gorilla tape to protect the rod cap. I wiggled and shook, and pulled and squeezed and cursed but finally got the cap free. However the channel lock teeth did gall the rod cap up a bit. I did 4 like this, wrapping the teeth up with pieces of cardboard and more gorilla tape and shaking the shi#t out of them to finally get them to break free. THEN, my brother came home and showed me how he has always removed rod caps in the old CAT motor. He took a 2lb brass mallet and holding the handle about 3” from the head, barely tapped on the sides of the rod cap. So lightly you could barely even hear it. About ten taps on each side and it dropped right down. No pulling, no cursing, no shaking, and no marks at all on the rod cap. So hopefully the ones I marred with the channel locks won’t cause any problems later.

The torque plus angle method sucks ass! Not too bad on the mains because it’s easy to mark for 180 degrees, but 60 degrees on the rod bolts is difficult to mark accurately, or it was for me. I would mark the cap across from one of the points on the bolt head then mark a point two away from the original and bring the two together. But depending on what direction you were viewing from the marks sometime looked off. My paint marker didn’t have a very fine tip so that added to the second guessing. JUST GIVE US A DAMNED TORQUE SPEC FOR GOD SAKES CUMMINS!!! How hard would that be!

Other then the above, things went well. It took way longer then I thought it would because I was working alone. The motor bars over nice and smooth. I had the appropriate play in all the rods after final torque. Also checked the in play in the crank which was good.


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User's Signature: Anti-seize EVERYTHING, Except injectors...Use Petroleum Jelly!!!
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03-30-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #17
RE: CM2250 764K, rod and main update!
I did my bearing roll at 685k, my bearings looked the same as yours. Glad I did them. I did my cam bearings too since I needed a new cam and the bearings were hosed. So far so good. Bought myself enough time to get to an inframe. Next time it gets cam bearings with a bearing roll itll be done with a whole new head.

If you are ever in doubt to do something preventative to your truck, just do it. Im my experience, its better to replace something questionable and know what you have than look back on the side of the road and wish you had. As long as you aren't blindly replacing parts for no reason, anyway. In the last 4 years, I've never had to drive to a dealer with it and she still runs ok, still pulls loads, etc...and Im grateful for that. Take care of it and itll take care of you.

Ive got 24k hours and almost 860k on it now. Doubt it would have lived that long otherwise. Shutting it down after this coronavirus thing settles down for a fresh build.

Yes, torquing the mains per cummins instructions is a PITA...I did mine on my back with a 4' long 3/4" torque wrench. I was sore for days but it was worth it. DEFINITELY helps to have another set of hands but is possible to do yourself, thats for sure. I keep the same wrench in my truck for tire changes.


User's Signature: 2010 T2000, CM871, 13spd, 850k, tanker yanker
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03-30-2020, (Subject: CM2250 764K, rod and main update! ) 
Post: #18
RE: CM2250 764K, rod and main update!
If you were sore for days, I'm feeling pretty good! LOL! Did mine on a sheet of plywood in Rawze's driveway... ;-)
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