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Discussion Starter · #1 ·
Hey all, I am new the forum here. truth be told, I am not swapping anything, I am rebuilding the 4B out of my case skid steer, and I am looking for a little clarification, I appreciate the help if anybody is able.

I am on the way with this project. its out and all torn apart. crank needs to be replaced. initial issue was a bad injector that ruined a rod, the bearing, and the crank. measured the block, and it needs bored 40 over on all cylinders. I got a crank ordered. I am about to order things from Pure Diesel Power. However, I am just stuck on this small piston/large piston thing. could anybody give me some info? Seems its not too straight forward, haha. My application is a skid steer, so I am thinking mostly marine style. I have been told it most likely has large bowl pistons. but it seems pictures on the web are so diverse and different. I just want to make sure I get the right piston/injector combo.

I am looking at this kit bored 40 over McBee 3.9L 4BT Cummins Engine Rebuild Kit
I am looking at these injectors 3.9L 4BT 8V Cummins Contagious 5x.011 SAC Injectors
Those injectors also will also need to be used in conjunction with the 7-9mm sleeves as my stock injectors were 9mm and cant seem to find those anywhere. they said this is fine.

These were all recommended by Pure Diesel after answering their questions, I am just following up/confirming because I am so confused about the piston situation. Here is a photo of my current pistons. Are these large bowls or small bowls? ughh!! haha.

Thanks for all the help!!
 

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Discussion Starter · #3 ·
Hey this has been a lot of help, and seems like you know a little what your talking about. I am an auto mechanic, very capable of doing the work, but dont know history and details of diesels much, so this helps. I can give you the ESN sure, it is: 44538150.

I will definitely have the head checked out, thank you for that info!

the pump has actually been replaced as well, it is this pump exactly D&W Diesel
which matched the numbers of the old pump exactly, and matched it in every other visible detail

so you think what I have is large bowl (of some sort, lol) pistons? which means I need large bowl injectors?
How do I know the injectors are matched to the pump? you said those injectors are sort of odd size? Do you recommend another set, something you can link me? Hoping somebody is able to confidently send me a link for a kit including pistons (bored 40 over) and then good matching injectors haha

sorry for all the questions!
 

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Discussion Starter · #5 ·
People keep asking me for a CPL number, but I cant find that anywhere. they said look on the tag on the side of the timing cover. i attached a picture of that tag. where else would a cpl number be?

I understand you wont be able to answer all my questions. you are giving a lot of good info, but I still need some clarity to put together the pieces of what your telling me.

So you are saying my pistons are large bowl? Ok, got it. Ive seen that photo comparing the two. I notice mine has the point like the large one, but the over all size seems to fall somewhere in between those two...idk maybe im just seeing it wrong
So, the kit that I linked.. are the pistons included in that kit right for my application? Or do I need to buy my pistons separate and buy a gasket kit without pistons? is there a 'wrong' and 'right' large bowl piston? as long as its 40 over... If pure diesel says the pistons included in that are right for my 4B motor, are large bowl, and I select .040 over, are we good to go, or are there many other details I need to know about? thats what seems to be the case, but maybe I am just confused by all the jargain and over thinking it....
and still dont know what to do about injectors, lol. How do I know a set of injectors is right for motor? simply if they say large bowl? or the 5x.011 numbers? (not even sure what that means yet) The spray patter? many injectors I look up dont even give the spary pattern degrees. or does that just coincide with large or small bowl style? ughh this is racking my brain!
thank you very much for helping!
 

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Discussion Starter · #7 ·
OK I am following you on the spray pattern info, how a square is a rectangle but not the other way around, I get that. but my uncertainty is, which do I have, and when I shop for them, spray pattern is not included in details usually
I tried to follow about which piston is lower compression - you said the marine style had lower compression, then gave it a rating of 17.5:1 which was higher than the other, so is it the marine that has lower compression?
I understand that I wouldnt want lower compression, that makes sense to me.
What about the numbers off the inside of my piston? 102018-21; 1275; also a 16, K, 40, B1

Ok so your saying the injectors that I linked might be a good choice? They dont list any of those numbers in the details either, so how do I know? ugh lol. I am thinking about getting mine rebuilt. But I wonder if they will be able to find the original 9mm tips, or they will switch them to 7mm as well?
Numbers on my injector body is 5568 also JH LJC6760501
the Tip has a number 6801079 also has an 'EGG 1' on the tip

I came across my Case manual. might have been help from the beginning! although when I google i still come up with different things. I attached pics of the piston page and the injector page. let me know if these part numbers help us figure anything out.

for example I search the A77412 number for 40 over and get this https://www.tractorpartsasap.com/cylinder-kit-100mm-040-new-case-a77412-166580.html I dont know what brand that is. and it doesnt tell me what size/degree bowl.

Thanks for all your help char1355
 

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Discussion Starter · #8 · (Edited)
I did just talk to a Case dealer, and they said 9mm tip part number has changed to the 7mm tip number, which would be JR919331 or J919331. and they confirmed the A77412 number. when I search the J919331 number I mostly get ebay listings and other random sites (plenty to choose from) with prices ranging from 100-200 for a set of 4. does that sound right? Am I fine getting some off ebay for $100? lol. they have case pictures on the listing and say they go right in the 1845c! lol
 

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Discussion Starter · #10 ·
Wow, thank you so much for all this help! This brings a lot of confidence to the table!
I did actually already buy some injectors before, sort of before I began all of this work, trying to just get ahead of the game. then months later as I did research i wondered if i purchased the right ones or not. I DID buy a set of cheap J919331 off ebay. 7mm that require the 9mm sleeve. are you suggesting that these are probably OK? or should I try to have mine rebuilt?
When you say Allstate listing, you mean this listing? https://www.tractorpartsasap.com/cylinder-kit-100mm-040-new-case-a77412-166580.html You think these pistons are fine/good quality, etc?

I do plan on doing the rebuild my self. I am an automechanic with lots of experience with engines, just not much on diesels. this motor looks simple, yes. I have just been racking my brain over the whole piston/injector/pump area, whats right, whats wrong, whats ok, whats best, etc.
I was not really planning on hot tanking it. its pretty clean as it is. yes head bolts need to be replaced, thank you for sharing that info, I did not know about the studs. I have the manual i planned on following whatever torque sequence they say, whatever ftlbs or degrees they say, ive done some weird ones before, so ill probably just go with oem bolts. if I put studs in, the torque sequence would change...to what? do they give that info with the studs?

do you know much about the rebuild kit that i linked? think that head gasket is OK?

I really appreciate you taking all this time to respond and help me out, thank you!
 

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Discussion Starter · #11 · (Edited)
I have found this kit for cylinder head bolts

I found these for rod bolts

On the injectors, another question. I said I bought a cheap set matching J919331. I noticed the nozzle tip protrudes every so slightly further down into the cylinder. very slightly. does this have something to with the difference between a 7 and 9mm tip? or is that something that is wrong and I should watch out for?

The head gasket I am getting some options. it says standard, or 2 notches or 3 notches. mine has been rebuilt before, and the gasket has no notches. I couldnt guarantee its the right one. or if no notches means Standard. here are some pics
 

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Discussion Starter · #14 ·
Ok that is good info on the head gasket. I did not know that the distance the piston protrudes above the block must be measured - I am used to rebuilding gas engines, usually not an issue! Is it possible that the top of my block does not need to be shaved at all? or is that highly recommended no matter whenever its taken apart? I figured the head should be checked for sure.
Ok so sounds like I need to order a kit and I may be scrapping the gasket that it came with depending on what measurement i get with the pistons - got it!

I am aware of the sleeves, and the copper washer, etc. when i compare the new injectors I got with my old injectors, I measured the distance the tip extends past the flange part (where the washer would sit) I measured both, and the new ones stick down further. the thickness of the sleeve-washer was the same as the old normal washer, so the tip would have protruded further down. you say that distance is important. what should the distance be? I attached a picture. you see the old compared to the new, tough to see but the new is longer. so would my goal be to make the new match the old, with accompanying shims/washers? or is there another specific distance I am aiming for? where do I get these varying washers to adjust the distance?
This is why I am tempted to get my old ones rebuilt, however, I bet they cant get the 9mm tips again and or they will come different length tips anyway and I am in the same boat.

I have actually been looking at this site a lot more now, if anybody has anything to say about it. Pure Diesel was able to help me less and less and answer less and less questions, so I kind of got turned away. I came across this site when looking for pistons. theirs were a few dollars more than the allstate listing, but they have everything else that I need, and their kits are a good price. here is the kit I am looking at
Cummins 4B 3.9L Inframe-Overhaul Engine Rebuild Kit - Naturally Aspirated
Obviously I would select 1.0mm over and standard bearing sizes, etc.

that kit should come with these pistons I believe, which I need to call and confirm
And they list the part numbers that match what my case manual has, so I think I am good there!

I really do appreciate all of this, guys!
 

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Discussion Starter · #16 ·
My injection pump is new actually too, haha! already sunk that money months ago! here is my exact pump, I bought it here
That leads me to my next question, what style pump is that called? is that a VE pump? or is it called a CAV Pump? any brief explanation on the difference?

Yes, I agree that there is the slight uncertainty without the CPL number. I figured if that kit includes those pistons which interchange exactly with the part numbers included in my manual, then I would be good to go. But I will also call a cummins store to try and get a CPL number. would be nice to have. any known places to call? Yea I still havent called them, but that AG site seems to a good one stop shop for the most part.

I will have my machine shop do the piston - rod assembly, valve seals, bore the block, check the head for cracks, and machine head/block IF needed.
 

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Discussion Starter · #18 ·
I was actually going to tell you the same info. I got in contact with Cummins customer service who said that case has contract with Cummins around that era and Cummins can’t give any info on it. So I went to case who said their records aren’t good before 2002 lol. But the guy is looking into it more for me tomorrow.

so what does that mean for buying things without cpl numbers, like that rebuild kit? Pistons should be ok as long as they Match that part number from my case manual, the A77412 for1.0mm bored. But will there be other issues?
 

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Discussion Starter · #21 ·
Interesting!
hmm, I dont see that injector number anywhere in any of my manuals. I found the other page where mine does switch it to 7mm J919331. I searched that number and it seems to cross over to the 919331 number as well. like these.
thats basically what i bought for mine, but I think i got some off some other knock off site other than ebay. you think something like that would fine? or is that price too cheap to possibly work? lol
 

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Discussion Starter · #22 ·
The thermostat page is missing out of my manual, ugh!! trying to find a listing for a new thermostat. do you happen to know what part number that might be? or a listing for the right one?

Also a new rod. I just need one. Pure diesel had one for a little over $100. price was ok. but Im getting most of my parts elsewhere now. I can still order that from them, but wasnt sure if you knew another good place to find a new/reman rod
 

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Discussion Starter · #25 ·
Awesome. thanks for the help! love that you found it on AG site for me, haha! I talked to my local diesel shop. they said they will rebuild my injectors for around $80, with 9mm tips. I am tempted to go that route. although the new ones I got might be just fine, would rather be safe than racking my brain again when it doesnt start! lol. then Id have an extra set, anyways.

They also gave me a good price on a rebuild kit. and good prices on a few other parts ive been looking for. I may get all my stuff through them, havent decided yet. I like the idea of getting parts locally (when the price is right, enough) that way when there are problems its easy to deal with and get it straightened out at least. waiting to hear back from them on some other things yet.
 

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Discussion Starter · #27 · (Edited)
What exactly is the killer dowel pin repair?
I just ordered everything today, rebuild kit, new rod ($60), all bolts, thermostat, new oil pressure relief valve (mine busted when removing oil filter housing).

think I should get a new oil cooler? Someone recommended that. Was just gonna clean mine out. And change the oil and filter 3 times the first hour of running it lol

im really hoping my head is ok. Lolol. If not, I’m in for a new or used one, which will prob be 7mm injectors, that’s why check the head first before rebuild them with 9mm tips? Lol
 

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Discussion Starter · #29 ·
Ok, killer dowel pin repair - got it!
back timing housing cover bolts, blue loctite - got it!
My oil pump looked fine. not even any marks on it from metal in the engine. I didnt plan to replace it. but will look for a listing and see if its not too much. If I needed to replace it in the future, its not a bad job. I am pretty good at getting that front cover off now, haha. 1 hr and I had it apart and together again with the motor in the skid steer.

yes, I believe mine is the first gasket, if I remember correctly. I found out this motor is a little older than I though. case gave it a build year of 1991.
 

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Discussion Starter · #31 ·
Oh my that is a lot to swallow for just a water pump, lol. I wasnt planning on replacing mine either. didnt have issues before. looked fine when I took it apart but i will look closer again and see if I can tell which design it is, or if it feels like its going to fall apart. Again, not a real hard job to do later if it needs it.
 

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Discussion Starter · #33 ·
I remember you mentioning something about the oil nozzles inside the block. I was just looking at mine, you mean the ones down the bottom on top of the crank bearing housing that point upward toward the cylinders? those are the only ones I can find. and I see that one of mine is missing LOL. I didnt ask if they came with rebuild kit, I guess we will find out soon, hopefully they did!
 

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Discussion Starter · #35 ·
No it was on a different cylinder. and i actually found it, it fell out and was on the floor. haha. I got my head checked, no cracks. my machine guy is going to get working on the valves, etc. and my parts should be here in a day or so and will get it bored and hopefully ready for reassembly end of next week.
 

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Discussion Starter · #38 ·
I put the motor together on Friday. Also got a call from my local diesel shop on friday saying they were having a hard time finding the parts now to rebuild my injectors. ughh, just what I figured was going to happen. that seems to be the trend with this thing..nothing is straight forward. the one that broke the nozzle nut, they say they need a core body to rebuild it, and they are having a hard time finding one. they say the others are good actually. my question is...if one broke and failed catastrophically like that, whose to say the others wont soon too? I asked them that, they said they looked good and didnt foresee any problems in the near future 🤷‍♂️

I am leaning back toward investigating these other injectors I got. in fact, I dropped them off at their shop as well, to have them test them and inspect them, see if they look and perform exactly to spec, and if everything else is correct, like that nozzle length and spray angle, etc. hopefully answers to those questions will eliminate some confusion.
these are exactly what I got: 4x Fuel Injectors J919331 Fits Case-IH Skid Steer 1840 1845C Backhoe 580 Super | eBay

So you said you seem to think that they are probably correct? obviously using that sleeve to neck them up to 9mm. i notice the angle of the tip is slightly different too, is that for the spray angle? does that mean the spray angles are different from one another?
 

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Discussion Starter · #41 ·
I appreciate that info, thank you very much!
As for update, the engine is back in and hooked up. just waiting to hear back about injectors yet from my local shop. and if I then need to, I will get in contact with Area Diesel Service!
 
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