N14, crazy high wear numbers

[sdan27]

This is an N14 engine in a Case 9370 articulated tractor that we use for a lot of field work. Its kind of had a history or high wear metals for us. I cut my sample interval way back and took a UOA last July and everything seemed pretty good and then took another just a week ago with another 170 hours on it and all my wear metals went way up again. I think the most recent UOA was Shell Rimula oil but I drained that yesterday and refilled with a Service Pro premium. Since we got it I've been using a Fleetguard LF9009 Venturi Combo filter. Unit has about 3600 total hours. I think I'll resample after 250 hours and see what is going on then.

Oil Chg y, y, y, n, n
Unit hr 2431, 2808, 3217, 3588
Oil hr 294, 377, 409, 200, 371
Iron 26, 38, 60, 47, 92
Chrm 0, 2, 2, 1, 2
Nckl 0, 1, 0, 0, 0
Alum 1, 1, 0, 1, 0
Copp 2, 4, 12, 4, 11
Lead 5, 24, 68, 17, 68
Tin 1, 0, 2, 1,
Sili 4, 6, 6, 5, 4
Sodi 5, 3, 4, 3, 6
Pot 0, 0, 0, 0, 2
Moly 13, 214, 82, 66, 73
Boro 48, 15, 11, 13, 12
Magn 117, 879, 939, 788, 899
Calc 2490, 1413, 1377, 1375, 1556
Phos 1000, 952, 1190, 1071, 1171
Zinc 1186, 1094, 1308, 1276, 1442

Fuel% .6, Soot% .4, .5, .8, .7, .8
H2O% TBN 5.99, 5.56, 5.99, 5.57, 5.33
Oxid 11, 12, 14, 11, 15
Nitr 14, 18, 20, 8, 11

 

[scurvy]

For 371 hours use (~14840 "on road" miles equivalent) the only thing I see about this oil analysis that bothers me is lead. Tin is virtually non-existent and copper is barely out of single digits... this could be the onset of bearing wear. Soot is trending upward but still less than 1%, fuel is virtually zero, TBN is strong.

Some engines just shed more metals than others. Continue your oil analysis and keep on workin'...

 

[A_Harman]

If I'm reading your numbers right, you had an Iron reading of 47 at 200 hours into the most recent OCI, then Iron went to 92 after another 171 hours on the same oil. The wear rate on the second UOA has gone up ~10%, which doesn't seem excessive, but a trend can't be determined on the basis of two data points.

Incremental Iron wear rates over the 5 UOA's calculate to be:
#1 = 26 ppm/294 hrs = .088 ppm/hr
#2 = 38 ppm/377 hrs = .101 ppm/hr
#3 = 60 ppm/409 hrs = .147 ppm/hr
#4 = 47 ppm/200 hrs = .235 ppm/hr
#5 = 45 ppm/171 hrs = .263 ppm/hr
or taking 4 & 5 together = 92 ppm/371 hrs = .248 ppm/hr

So the incremental Iron readings have been increasing over all 5 of the UOA's. Something may be going on in there, and it seems to be accelerating:
15% wear rate increase from 1 to 2
40% increase from 2 to 3
68% increase from 3 to 4&5 combined.

Copper and Lead concentrations are fluctuating together. When Copper goes up, Lead goes up. When Copper goes down, Lead goes down. Maybe something going on with a bearing.
Copper and Lead are fluctuating along with the Iron.

When was the last time the valve lash was checked? I'm thinking that checking the valve lash would at least eliminate that system as the source without having to get deep into the engine. But I don't mean to sound alarmist; the wear metal concentrations are still low. I only mean to point out that wear metal rates are increasing. Maybe that means the engine is finally breaking in. 3600 total hours is not much for a heavy duty diesel engine.

Can you cut open the filter from the last oil change and check for debris?

 

[dnewton3]

I don't have enough history on this engine, so I have nothing to compare/contrast it to directly for averages and deviations. While I do have a few UOAs gleaned from indiscriminate sources, I don't have enough to get full statistical data. I can try to scare some up.


Anecdotally, I'd say there is some heavy wear going on. I presume the tractor is used in ground-engagement work, so it's heavy loading? Are you seeing the wear number fluctuate with the loading?

Sometimes it is easier to say what is not the problem, as a process of elimination. It is easy to exclude some things as the tell-tale signs are not present:
- it's not soot; your particulate loading is very low
- it's not coolant; your pot and sod are low so the gaskets are fine and there no head or block cracks
- it's not moisture; your H2O is low showing the engine comes to temp and evaporates out the moisture
- it's not fuel; too low to be of concern and not thinning the vis
- it's not dirt; the Si is admirably low, especially given this is a farm tractor that's used in the field
- it's not cylinder wear? Not sure here, but the reason I say this is because the Al is very low. Does this engine have Al pistons?

After excluding the above, it pretty much leaves a few things to think of:
- EOM manufacturing defect; always a possibility
- EOM design defect; not a big issue I'm aware of given my word-of-mouth info on the N14. Feel free to correct me if the engine family has known issues

Given the Pb and Cu readings running sympathetically, and in tune with the OCI duration, I'd have to predicate a guess on bearing wear that is actually allowing the Fe to spike as well (either camshaft or crank). If it has Al pistons, we can rule out the cylinders/piston relationship. Even if the engine has Fe pistons, I still don't suspect the piston/cyl relationship because there is no large presence of Cu and Pb in the cylinder. The Cr is very low; again that pretty much rules out piston rings in the cylinder.

That pretty much leaves the suspected area to be a place where iron and copper/lead interact; hence - a bearing.

This is the kind of wear I think of when I have seen manufacturing and/or design issues. Either a bore was not straight, or a bearing installed poorly at the OEM, or a blocked or restricted oil path due to some manufacturing error. Or, perhaps there is a design flaw in the oil system or undersized component? I just don't know the lineage of this engine series well enough.


Fundementally, this is why we do UOAs. We are looking for abnormalities. And this is truely a sign here.

I completely agree that it's not time to panic, but it is time for continued monitoring and evaluation. The metals are not so concerning in total magnitude as they are in trending direction. There are five successive UOAs where Fe, Cu and Pb are on the way up per hour of exposure. That is an undesirable trend. It is not a fluke or a spike; this is a trend.

Checking the valve lash can held eliminate another potential cause, as Harmon suggested.

The real question is this:
Is it time for a tear down, in an effort to stop any further wear before other components are harmed, or run it out and see how far one can push it?

 

[A_Harman]

What is the warranty period on the engine in your tractor? It only has 3600 hours on it. I recall from my time at Cummins that their on-highway heavy duty engines had 6000-hour warranties. Since you have been tracking increasing wear metals from the engine condition with UOA's for the last 1450 hours, you may have a good basis for a warranty claim.

 

[sdan27]

The engine was manufactured in 1997 so I doubt there would be any type of warranty remaining. I think I'll do a valve/injector adjustment when I get the time. I wanted to do it last winter but never quite got around to it. Then, like, I said, I'll do another sample after another 250 hours and see what it looks like then. It seems like you get a certain hour threshold and the metals start going way high. I do like extended drains but I could live with just doing 200-250 hour changes if the wear metals stayed down. It does seem like to me that it is some kind of bearing wear. I have thought it could be some kind of design flaw but the first UOA I did had nearly 300 hours and looked great. That was the oil that came in the tractor when we bought it so I'm not sure what kind of oil it was. If the metals stay high maybe I'll drop the pan and roll some new bearings in and see what the originals look like. Pretty much all we've used this tractor for since we bought it was pulling big, heavy tillage tools.

 

[A_Harman]

Factory fill was probably 15w40 Premium Blue.

 

[sdan27]

Are factory fills usually engine manufacturer oils or equipment manufacturer oils? I would have guessed the factory fill would have been like a Case #1 engine oil or something. Do they ship new engines with the oil in them or do they wait until they install them?

 

[Colt45ws]

Varies I think. On my line at work the engines we get are already filled from the engine manufacturer, but the next line over has to fill them.