Cummins QSX15 burning oil...

Neighbor has a big Versatile/Buhler tractor with a QSX15 Cummins, 1600 hrs. from new.

Suddenly started burning a gallon to a gallon and a half of oil a day.

I suggested pulling an oil sample, but they had just changed the oil.

Got Cummins to look at it, wrench thought it might have been "dusted" and checked air filter and tubing and turbo and found no signs of dust. Checked for oil loss in the turbo, as well.

Runs real well, with no visible smoke.

Owner was told by a couple of "experts" that the positive valve stem seals can move up off of the guide, then they'll burn oil.

I said losing a lot of oil past the valve guides isn't likely on a turbo diesel, where both the intake and exhaust ports have positive pressure.

I told him it is only in recent times these big diesels even use valve stem seals, because with strict emissions rules, even containing a slight amount of oil is important.

He persisted in obsessing over this 'til we pulled the valve cover and (using an inspection mirror) looked at all 24 valve seals, which seem to be in place down on the guides and all the little garter springs on the seals are intact, as well. Another "expert" told him one may be cracked.

When fieldwork starts, they are going to run it for a couple of days, checking the oil often, to put some hours on the new oil, then send in an oil sample.

Summing up, my question for the group is "does anyone believe a failed valve stem seal on this engine would lead to huge oil consumption"?

Opinions wanted!

I had that once when I changed oil brands in an N14 Went from Delo to Delvac Stopped in a coupla days.

How much is he using it? When I was at the dealer they (service block man) said they're supposed to use up to 1% of the fuel usage, and wouldn't warranty tear down anything under 4%. If he's going through one hundred gallons of fuel a day then a gallon of oil is 1%, of course this was before electronic engines with emissions equipment(straight 855, not even N14).

Hello bob,

Do you know what is the air restriction gauge reading? Should have a gauge on the cash? Anything close to 20" could be an issue . 25" is the replacement max for air filter element change.
Late injection timing (high injectors settings) will cause cylinder wall washing and increase oil consumption. EMPA sample will prove oil delusion by the fuel. A dribbling injector can do the same. None of these symptoms will show abnormal exhaust change, although power would be affected at low R.P.M.s

Guido.

Had a big Kawasaki loader at a feedlot with about 5000 hours that would burn a gallon a week . Could have had a lot to do with operators starting it at 30 below and as quick as it was running it was full bore loading feed trucks

I would think with that kind of oil consumption there would be some smoke noticed. If it's not leaking then its burning it, does this run 24hrs at full load?

I'm not too keen on the big ISX's but aren't there injector seals and possible pump seals that can push oil into the fuel system. Of course this would be easy to verify by looking at the fuel color

I'm sure someone has checked the crankcase ventilation right? If the crankcase can't breath (blow-by gases) It will push the gases through valve seals and up the turbo oil drain tube, both paths pushing oil with them. Since no oil was found in turbo, probably can't suspect the turbo or turbo drain to be the problem.