VXer in the Sky
Can someone please explain how the Exhaust Gas Recirculation system (tube or valve) being clogged has anything to do with oil consumption? Is it recovering partially burned oil from only the passenger side exhaust manifold and then redepositing it back in the intake trac where it is burned again or somehow seeps back down into the pan? Keeps the intake air charge hot? I just don't understand....
Super VXer
Originally Posted by Tone
Very good question!
Amsoil
If the EGR valve malfunctions, engine performance is dramatically reduced. An EGR valve remaining in the open position will result in the engine stumbling or stalling at idle speeds. When the EGR fails to open, combustion temperatures cannot be limited, causing higher cylinder temperatures and an increase in NOx emissions. Engine ping or knock may occur, especially when the engine is under load.
In either case, drivability problems arise and NOx control is lost. The loss of NOx control results in rapid degradation of the engine's motor oil. NOx shortens oil life by increasing oil nitration and decreasing the oil's ability to neutralize acids (TBN) and maintain internal cleanliness, resulting in oil thickening and/or the formation of sludge within the engine.
Bob F Note: Increased Oil consumption is a resultant of higher cylinder head temperatures
Bob F
As far as the PCV Valve & the Isuzu 3.5 eng is concerned. It is my belief that if the PCV valve fails closed, then the resulting increase in crankcase pressure overcomes the drain thru of some oils thru the oil ring ( Isuzu design deficency) subsequently resulting in a rapid loss of engine oil. Catastrophic engine failure soon follows. Using a good quality fully Synthetic oil & changing the PCV & oil filter every 5,000 miles or less are my preventative measures to deal with this situation.
Neither ordinary or extraordinary, just indefatigable.
2000 VX Green Dragon- Chick Demagnitizer-Supercharger-Injen Intake- Cold air box-K&N- Power Vault SS Exhaust-265-75-16 BFG MT kms-On Board CO2- Custom Boulder Bars- Custom Skid plates- PIAA 520 Fog Lites-3inch lift with OME 912 Springs-LINE X Bedliner on Cladding & Hood Insert-ARB Front Lockers & Custom Bull Bar. Vintage Offenhauser Hood scoop Thule Rack. XM Radio-Custom Storage Box-First VX to surmount the RUBICON.Thanks Sierra Stompers
VXer in the Sky
That still does not explain it - think about it, it is feeding HOT air into the intake charge when it's open! If it is closed, then it does not feed hot air in. I ran with Bob Land headers that did not have the EGR connection and had no problems other than the check engine light. EGR is an emissions additon and not a blow up your engine thing.
I do agree with the PCV being clogged and blowing oil out through the rear seal.
Super VXer
i can see it getting hotter with it open ,not closed . maybe its a typo. when i cleaned mine the other day i noticed it was sticking in the open position. shawn
Last edited by psychos2 : 05/05/2005 at 05:12 AM
1COOLVX
Super VXer
"When the EGR fails to open, combustion temperatures cannot be limited, causing higher cylinder temperatures and an increase in NOx emissions. Engine ping or knock may occur, especially when the engine is under load."
This is interesting to me as well, if the EGR sticks in the open position, Cyl head temp rises. If ping or knock occurs then I would presume that the knock sensor would retard the timing, since the timing is initially retarded for emissions control the very least occurance would be a corresponding decrease in the complete ignition of the fuel/air mixture. ( Poor Gas mileage- less power).
I am not sure that the rear seal in this particular instance is an issue when the Isuzu engine PVC fails closed. The seal most certainly has failed in the past (other engines) whenever crankcase pressure has been excessive but I am unaware of crankcase seal failures in Isuzu engines.
It is an interesting discussion but unless Isuzu provides us with the failure analysis data (Highly unlikely) our theroms right or wrong remain unproven.
As for my VX, I think best to apply the aforementioned semi rigid prevention methods I alluded to earlier.
Super VXer
I always thought that one of the side benefits of a properly working EGR system was cooler cylinder temperatures.
When I bought the first VX, the Isuzu tech(s) told me to immediately change the oil with Mobil 1 0W-30. Maybe this was to combat the oil drainage issue right off the bat.
Wait a minute...
3 piston rings, top to bottom
Compression
Compression
Oil Control/scraper
Crank case
Why exactly does oil need to drain through a hole in the piston/ring land in order for it to be returned to the crank case -shouldn't it drain down there on it's own with every downstroke of the piston?
Super VXer
That is what I thought initially, but my research into this subject turned up this interesting NASA report that addresses this issue ( albeit a different engine)
This is a good read.Especially pages 4,5&6.
http://naca.larc.nasa.gov/reports/19...ge00000004.gif
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