Bearing analysis??

[hotater]

THis is the third bearing that's done exactly the same thing after just a few minutes of running.  Anybody know how or why these voids develop?  There's 1900 hours on this bearing.

http://community.webshots.com/photo/2748978100028237237seCffv

[kyradawg]

Peace&Love , Darren

[Geno]

There is some good info on this .pdf   The pics that look like your problem don't forbode well. Others with more experience may know more.

http://www.engineparts.com/publications/CL77-3-402.pdf

This is what Clevite says a lack of oil looks like.


Thanks, Geno

[GuyFawkes]

THis is the third bearing that's done exactly the same thing after just a few minutes of running.  Anybody know how or why these voids develop?  There's 1900 hours on this bearing.

http://community.webshots.com/photo/2748978100028237237seCffv

http://www.surfbaud.co.uk/Lister/Files/CL77-3-402.pdf

will answer all your questions

read what is there, don't be tempted to pick the answer that appeals most because it is cheapest / quickest / easiest / nicest.

[GuyFawkes]

There is some good info on this .pdf   The pics that look like your problem don't forbode well. Others with more experience may know more.

http://www.engineparts.com/publications/CL77-3-402.pdf

This is what Clevite says a lack of oil looks like.


Thanks, Geno

aye, just linked to that myself.

the picture you show is wiping, he has some wiping but he also has surface fatigue, that's not good because it means you have to check and eliminate journal shape and form and rod straightness, and then be real finicky when reassembling to make sure EVERYTHING is within tolerances.

[GerryH]

Hotater,
Looking at your picture, it seems to me that the oil channnels cut from the oil holes have distributed oil as they are supposed to, and the outer edges of the bearing look ok as they recieved oil, while the centre without the oil channels has starved for oil, and heated as a result. The spalling and peeling might be prevented when you install the new bearing by cutting oil channels into the centre area of the bearings. I drilled my a hole in my dipper and a right angle hole in the leading edge of the dipper to oil this centre area. Time will tell me if this was effective.

[hotater]

I sure wish I could photo through the stereo microscope....  the missing material shows NO signs of being mechanically removed.  The surface of the cap is visible as a tinned surface but not pulled or torn apart.  There are large areas with 'wrinkles' in the surface showing discontinuous material, too.  The bottom shell has NO damage at all.....perfect in every way.  The top shell, microscopically, is just FULL of grit and tiny flakes of brass and paint.  The bottom is clean.

This is the third set of bearings in the engine.  I never ran it with the OEM shells...they're a LOT worse than this one!!!  The second lasted 4100 hours and this one about half that.

WHERE did the material GO that ain't there now and how did it escape??

[GuyFawkes]

look at the right and left (of the picture) edges of the bearing, there is a distinct pattern there indicating excessive crush

looking across the bearing from top to bottom (of the picture), there is a pattern indicating out of shape journal

looking at the centre of the bearing (of the picture), there is surface fatigue.

a/ rod needs to be checked for straight

b/ journal needs to be THOROUGHLY checked for ovality and taper etc

c/ rod needs to be carefully cleaned and inspected and assembled, ideally on a known good mandrel, and tested with prussian blue, failing that assembled on the journal and tested with prussian blue

despite the size and mass of these things, they need to be assembled with delicacy and care.

I'm trying to think of a gun related example, but I don't know shit about guns so all I can think of it a revolver, the drum needs to fit within certain parameters, gap to barrel, gap to firing pin, I'd guess too small a gap and things jam, too big and brass bulges and other bad things happen, I suppose a revolver can be a ways off, and still fire, but how is accuracy and longevity and so on? I dunno, hopefully it's a useful example.

[Halfnuts]

Mr. Ho, just wondering if your bearing caps were shimmed earlier.  A quick check with PlastiGauge in several locations around the perimeter of the bearing shells will give you your bearing clearance.  I'm wondering if maybe your journal might have worn slightly oval over time.  Just a thought.

Halfnuts

[cujet]

Hotater, you say this happens after a few minutes of running? I suspect cavitation due to shock:) Try an oil with longer links in the molecular chain:)

Chris

[kyradawg]

Peace&Love , Darren

[hotater]

I think you've got it!    This engine has picked up a slight knock that I can't find.  I was just sitting here wondering if timing  could have gotten off somehow.
  I found the bad bearing first thing today and thought I'd found the knock, but it didn't help a bit, so I pulled the piston thinking it was a wristpin or bushing.  It wasn't.  Gotta be timing.

I'm surprised at the difference in 'attitude' between this engine and the SOM videos.  Mine sounds like it's 'hitting' and theirs sounds like they're 'missing'.

I'll run a timing check in the morning.

[mobile_bob]

i am going to ask a couple of ignorant questions, because while owning a twin i have never been inside a lister/oid

1. i assume this is a main brg cap, evidenced by having thrust brg intregal to the brg, is this a main?

2. if this is a main, is it the center main of a twin?

3. looking at the picture again, it looks like maybe the big end of the rod, yes?

i would choose to believe it is the big end of a con rod, so then i would ask the following

1.  i see two holes with oil channel intersecting them, is this how oil enters the brg, from cups in the outer top of the rod, or..

2. is this how the engine moves oil up the rod by a rifling to oil the pin?

the reasons i ask are many fold..

it comes down to sound engineering principles,

1, if this is a center main cap, then why have the holes and the oil channels, to divert the oil wedge out of the brg,,, this would be senseless.

2, if this is the big end of a rod, then again, i would think this method of oil channels defeats the hydraulic wedge and diverts it rather that giving oil to the brg. not a very good design either.

clearly in any event there is insufficient oil cushioning the brg, and causeing shock loading of the brg, which in turn pock's out and flakes, or  you have an early timing event that overloads the brg beyond design parameters.

please tell me what brg cap this is, it has my curiousity up, as i have never seen diesel engines designed with either a rod brg with thrust shoulders, or either a rod or main with oil diversion channels such as these.

also it would appear if the brg exhibits this sort of pattern near the parting line on each side in a short run time, you have excessive brg clearance which would exacerbate the problem.

i gotta get busy and see the insides of one of these monsters,

having spent so many years on american iron, there is much that is different about the way these engines are engineered.

bob g

[hotater]

Bob---

That is the big end of the con rod.  The two oil holes align with holes on each side of the rod that have counterbores to catch and presumably hold enough spash lube oil to feed the bearing.  The big end cap has the same shell but only one central hole that serves as a 'stop' by way of the dipper that screws in part way and prevents the shells from spinning.

There's NO doubt the fitting of this bearing is critical AND done very wrong in this case.  The crank pin was 'triangular' in profile by .008 and very rough when I got it.  I spent a couple long afternoons polishing and rounding the crank pin until it was round to within .0003 and straight to .0004, but there are still rough chatter marks in places from an untrued grinding wheel and now there are circumventional scratches caused by running with contaminated bearings.

Plastigage shows  .002 clearance in four places with new shells and .0015 in two places.

I have to build a place to put this beast.  It's torn up everything it's ever been bolted to including 6 inches of concrete floor.  I might try to schedule a down time during the re-mount stage to pull the crank and have it ground correctly.   Trying to correct an out of round crank pin while still in the case is NOT fun.  For now, I'm trying to keep it running it until a LOT needs done.  If I have to run a big genset it means I'm VERY short on fuel and have less than three weeks supply.  The Listeroid can run six months on the same fuel.  Rebuilds are EXPENSIVE when you're off grid!

Contamination is the biggest and most aggravating factor here.    When I mounted the first of the "catcher on the door" oil filters or I recovered nearly a half a gram of sand, and paint particles!!!  After running six months with such a filter and changing the washcloth 'element' every 200 hours that amount of debris has been cut in half  BUT is STILL shedding sand and grit and paint and particles in just amazing amounts!!  There's enough solids washed out of a filter element to cover the bottom of a mayo jar lid completely....and looking at the big end shells, there's nearly that much stuck in them, too.

I've been watching the camshaft end next to the pressure pump tappet for signs of excess wear...its' there, but not quite  bad enough to change it yet.   Yesterday I decided to go on and pull the cam and replace both bushings.  I found the bushings were fine.  The camshaft ends are wearing away!  That means more sand has gotten in the new bushings I installed before the engine was run!!

My advice would be to strip these beast down to the bare cast iron, clean them using American techniques (dipping, boiling, steam cleaning, shot peening, solvent washing...or all of the above,  then SEAL everything with a paint made for the purpose.
I think what my engine has is a cast iron sponge for a crank case and without complete sealing will continue to shed sand and wear out parts.

I'm going to retard injection timing some today, if I can get some time.  I timed to 23 degrees and when it cranked on the first try I *assumed* it was right.  Maybe it isn't.   For sure it 'sounds' totally different from the original SOMs.

[mobile_bob]

all i can say is wow!

you mention a dipper screwed into the rod cap, that also locks the brg from rotation,

does this dipper feed oil up into the brg? thru the rod end cap?

in my mind that would be the proper way to do it, but then again, i find the design quite different than what i have
been used to building.

i would rather see the oil come up thru the rod cap, into the lower brg shell and then by force of rotation form the wedge up over
the upper brg and do away with the oil holes and grooves,,, but that is jut me i guess

as for sand and grit.

years ago i was trying to illustate why cleanliness is next to godliness in engine building and maintenance,

the guy i was relating this too was a bit younger and my assistant at the time, i had him get me a bit of dust off the shop floor, to which i dipped my finger tip into
clean oil and then into the dust,
i rubbed my finger in a circular pattern on a piece of glass, about the size of a quarter, i rubbed it hard for a minute only
wiped it off and you could clearly see the glass was dull from micro scratches.
i told him, there is nothing in an engine harder than that peice of glass, and alot of things more persistant than my finger.

one thing i am sure of, is the fact there is nothing in a listeroid harder than glass.

sorry to hear all your horror with dirt, dust, sand and paint in your engine

bob g