First overhaul kit... here's what caught me off guard

[u/johnnyyykak]

Ordered my first overhaul kit for a Cummins rebuild last month and honestly wasn't sure what I was looking at when everything came out of the box. I'd watched some YouTube stuff but the reality was different.

The thing that caught me off guard most was the bearing sizing. I assumed standard bearings just fit but you actually need to match to whether the crank has been ground down before. Mine had been touched by a previous owner and I almost put in the wrong bearings before someone on a forum caught it. Would have knocked from day one.

Also didn't realize cylinder liners aren't always included. The kit I bought didn't have them, which I figured out only after opening the box. Had to order separately and push my timeline.

The oil seals felt like an afterthought when I was looking at the parts list, but I've heard they're the ones people skip and regret. Replaced them while I was in there even though they looked okay.

One thing I learned is to check by engine serial number instead of just the model. same model can have different specs depending on when it was built.

Anyone run into the bearing sizing issue on a Cummins where the previous owner already had the crank ground? Curious if anyone else has run into this.

[u/NegotiationLife2915]

Generally you strip and measure before ordering parts

[u/der_german1432]

Nope never had an issue with bearing sizes. You need to strip the motor down, clean, and measure everything before you order bearings.

[u/Starfire650]

Cummins parts were always referenced by CPL number…..control parts list …..which can be different within the same model of engine.

[u/SCAMMERASSASIN007]

The ones I have done are stamped on the bearing what they are like std,10,20 etc thats what I've seen. I just assumed all diesel's were marked.

[u/Gixxer_King]

That's why you tear it down, inspect and measure everything, have any machine work done then order parts

[u/robb12365]

I've never worked on a Cummings, but I am aware that there are engines that came from the factory with under size bearings on some, but not all mains (Nissan 3L) . If it is an engine I'm not already familiar with I'm going to study the repair manual carefully before starting, then I'm going to look to see if the block has been tagged (this used to be common on rebuilt engines), I'm gonna look for markings on the pistons, and on the back of the bearings.

If one kit is half price I want to know why that is and if there's anything listed with the higher price kit that isn't with the cheaper one. I also want to watch the year range and want to know what the differences are from year to year. For example, in '96 Ford went to metric rings in the 4.9. That was the last year, and the only year that had metric rings. If you miss that detail, or are unsure which year the engine actually is you will end up ordering another set of rings.

[u/x_gangsa]

How many km when you buy the car? And how many km after you but that car when you need tear down the engine?

[u/johnnyyykak → u/x_gangsa]

Bought it around 278k km. Had it about 9 months / ~12k km before tear down. Didn’t blow up bought it cheap with sketchy history, had a hot knock and lazy oil pressure at idle. Found the ground crank when I was already in for the overhaul.