isuzu nqr oil consumption

[trim4u2nv]

We have a NQR diesel turbocharged truck that just consumed about 3 quarts of oil on a 200 mile highway trip.  Seems to be a lot of oil film on the right side of engine ahead of the turbocharger.  This is an inline 4 that had the exhaust break replaced last year.  Any ideas where all this oil is going?

[Rockn H]

Three quarts should leave more than just a film.  There should be oil blown back causing a pretty good coating.  Check the turbo good for any oil leaks.  These probably want show up more than just a small amount "thin line" at the flanges.  If the seal was leaking on the intake side you would have a run away so it sounds like it could be on the exhaust side.  Any oil or white smoke out the exhaust?

[trim4u2nv]

No oil at the exhaust.  But the check engine light was flashing around the middle of the trip and stopped.  The fluid levels were ok at this point.  Noticed drips of oil clinging to capillary hoses on the drivers side which may be pcv or egr parts.  The turbo seems bone dry though.

[Rockn H]

Well, no oil around exhaust and turbo are good.  When I thought of 3 quarts without a lot a mess that was my first thought. ;)  You may have to do some degreasing and let the engine idle for a while so the air (at highway speeds) doesn't blow the oil too much to identify where the leaks are.
One other thought.  Does the truck have an oil cooler running to the radiator?  Have you checked the coolant in the radiator itself?

[trim4u2nv]

Just to confuse the matter the transmission cooler (plastic tube) in the radiator did leak out some time ago, but was replaced.  (No more rise in transmission fluid level.)   Because of this, there is some residual oil in the radiator still bubbling to the surface every now and then.   The dipstick is nice and black no white residue indicating head gasket or block problems.  All I see are just a series of small cans like mini fuel filters on the drivers side that have capillary tubes that are coated with the most oil.   There is also a breather tube (open ended) near the bottom of the engine that occaisionally leaks out some oil also.

[Rockn H]

trim4u2nv, have you made any headway on figuring out where your oil has gone?   When your dealing with headgasket problems you need to remember that the cooling system usually has a radiator cap that will only hold around 12 to 15lbs of pressure on the system, while your oil systems in places has upwards of 60lbs or more.  I'm not saying you have a gasket problem, just something to keep in mind down the road.   The breather tube at the bottom of the engine is commonly reffered to as a blow-by hose a few drops of oil is not uncommon, but 3 quarts would have the under side of the truck dripping. ;)

[rebocardo]

I have seen more then one diesel that had a bad leak because someone did not put the filter on properly or tight enough. Been a while since working a a NPR, so I can't remember where it is. I just remember how much I hated changing batteries.

[trim4u2nv]

Mechanic is going to steam clean the engine and let it idle to see if it leaks down anyplace obvious.  Only major work done on this was exhaust break replacement under warranty.   Oil filter is under drivers seat and bone dry.  Most of the oil is on the front of the engine left and right sides.  Maybe a line or crankshaft seal?  Rented a Mitsubishi Fuso.  Very nice truck.

[getoverit]

I had a similar problem on an engine once and took me forever to figure out where it was coming from. Seem there was a small tube running from the engine to a oil pressure sensor that had broken off and was blowing out just enough to cause a good leak.

[rebocardo]

> Most of the oil is on the front of the engine left and right sides.

Isn't the engine oil cooler behind the front bumper? Could it be coming from that?

> Rented a Mitsubishi Fuso

The 4x4 makes a very nice small plow truck.

[scsmith42]

Check the oil pressure guage sending unit where it goes into the block.  Often this problem occurs with a bad sending unit.  Also check the oil drain tube from the turbo back into the crankcase.

[trim4u2nv]

Finally resolved the oil problem.  First the trans cooler line leaked oil into the radiator and was fixed.  Then the residual transmission oil in the coolant confused the issue.  The internal engine oil cooler was also leaking engine oil into the coolant.  The transmission fluid and engine oil both looked black when they floated to the top of the radiator.  Resolved the issue when I would siphon 1 quart of oil from the coolant and added 1 quart to the engine.  The transmission level remained constant.   Engine oil cooler came out from the inside of the block behind the injector pump.