Bed Plate Campaign (M-11)

[Archive]

A quick heads up for anyone running or maintaining M-11 engines. There is a bed plate installation campaign by Cummins for certain M-11 engines. I don't know the affected serial numbers. There was nothing listed on the Cummins website. The bed plate installation will (hopefully) prevent block fretting from occurring. Good Luck.

 

[Wayne M.]

Top Fuel, what is exactly happening? I help maintain a fleet of M11+ powered trucks, and a while back there was a problem with the piston cooling nozzles breaking. Was this the fix? We had some trucks go back to Cummins for warranty work, and I haven't figured out why yet.

 

[kaffine krazed]

My understanding is fretting is when the main caps don't fit right or aren't secured enough and move in the block wearing the cut out in the block that is supposed to keep the main caps from moving.

 

[Archive]

Wayne, I can't say exactly what is happening. The first fretted engine we found was when the engine could not be barred over to run the overhead. We dropped the main bearings and #5 had an abnormal wear pattern on the insert. Very abnormal. This was before we were notified of the campaign. Cummins ended up replacing the block. All the affected engines we run are in 1999 model year tractors.

Kaffine, it seems to be a chicken or the egg situation. Do the caps loosen and then move or does the poor fit (and consequent movement) cause them to loosen? There are 35+ excellent mechanics here, and a couple other theories are also being kicked around. I personally believe (guesstimate) that the machining is off and the caps are loose in the saddle at the time of assembly. I hope the bed plate repair will hold up. I have nothing further to add than that. Good Luck, Gentlemen.

 

[kaffine krazed]

No I don't know what causes it. I just remeber discussing it in one of my diesel classes.

 

[R.E. Miller]

Yup I have seen this at work. Interesting idea. Have you guys had any failures after doing this procedure? I saw one truck lock up the #7 main bearing before it even saw the dyno Just checking



Russell

 

[A Johnson]

Main cap fretting has become an issue with the high horsepower and torque outputs of the Celect engine, and mostly seen at high miles.

I'm not completely sure what happens, whether it is main bolt stretch, funny torsionals, or what. I do not beleive it is a sloppy original fit. There was a stop gap measure of using loctite on the main bolts but it obviously was not the ultimate fix.

I would think that if Cummins has come out with a bed plate upgrade then it must have been a torsional causing the problem.

This is not unique to the M-11 engine as I have seen it on several high mileage ( I. E. 1,000,000) High horespower N-14s' as well as one NTC444. Anyone doing overhauls on these, needs to be aware of the issue and check all main bearing caps for fretting prior to proceeding. This does not make these a bad product, it is just a new service issue to be aware of. As MR. Miller has alluded to , they will probably not make it out the shop door after new bearings are installed due to reduced oil clearance. -A Johnson

(not the official Cummins answer in any way shape or form)

 

[Archive]

I'm not ignoring anyone or refusing to share information, but I am required to sign legal waivers that strictly limit my discussion or dissemination of what the corporate attorneys refer to as proprietary business information. The bed plates are being installed to stabilize the main bearing caps. (From what I have been told. ) So I will stand by my original personal opinion of the cause until Cummins officially states otherwise. The block replacement rate has been much higher that what anyone here in our maintenance facility had originally ventured to anticipate. (IMO) Cummins is very aggressively addressing this problem.



We are purchasing 400+ power units this year to beat the EGR implementation deadline. Not all of them will be Cummins powered. If the non-Cummins powered units are well received by our drivers and perform well in regards to power, fuel economy, longevity and serviceability then everyone's job here will expand into a whole new dimension of hardware and electronics.



Most of you gentlemen are aware of the fact that my '99 Ram/ISB is gone... however, in my defense, I do still "own" 15 Cummins B engines (12 valve P7100's) vicariously from the necessity of fulfilling the requirements of my employment. Think about it. That's 14 more than Sam M. owns. Cut me some slack.



Have Fun.