N14 Rods and Mains

In for answer, 1 red top just crossed 1M and still pull strong. Id like to keepp it that way.

 

That's a good question.
I was concerned about mine to so when my oil pan seal started leaking I brought it to a Cummins dealer for repair, and had the rods & mains inspection. Mine is at 800k, and they were declared to be AOK.
Mine idles @ 700 rpm, 18 lbs
Under load @1500 rpm, 35 lbs

 

We usually recommend rod and mains around 750k on an N-14 (at least inspection). If you service your vehicle and take care of it I am sure you can get much more. Usually an N-14 is a 1.5 million motor (if taken care of) so at 750K you are mid point of its life. Why wait until 1.2 when you will have to do it again after another 200-300k miles is why we say around 750k.

 

have you ever gotten an oil analysis done on the engine?

 

A n14 with 840k is getting up there. I'm sure if they get inspected they will show considerable wear. There is no way to know when to do bearings other than havin a look at them. Freight trucks running over the road last much longer than the local dirt guys.
Main cap fretting can be an issue on early models. Late 1997 there was a change to main brg bolts & tightening procedure. The fretting is worse on trucks that haul heavy. Any caps that show fretting must be have the clearance checked with plastigage. A cummins shop will know this, a local guy may not.
Measuring the clearance is a real pain in the butt & adds a bit of time to the job. You can chew up a day doin a beaing roll.
Im not sure what the parts cost but its safer to change them before they fail.
You're shooting for big miles but I don't think the bottom end will make it. I would change them out & know that they will last.

 

how long will it take to do a bottom end on a red top cimmins?

 

Wish they brother back the N14 ... The last good motor Cummins made!!

 

I have one with a million 4 on it and still running strong other then there crap injectors. Well I shouldn't say strong she's getting tired but I'll blow it and stick a used one in someday.

 

If oil pressure is good I wouldn't bother with them at this point, especially if you've had this engine since new and don't abuse it. We recommended doing rods and mains on used engines simply because you don't know the history and it was pretty cheap insurance. If I recall Cummins came out with a "stiffener plate" similar to what CAT uses to combat the fretting issue, so when you do decide it's time I would look into adding that if yours doesn't already have it.