Isuzu Turbo Diagnostic Tips

Model Year Trucks 2007-2010 Isuzu N-Seines and GMC W-Series
Diesel Engine 5.2L (4HK1), Equipped with Diesel Particulate Filter

2007-2009 Isuzu F-Series and GMC and Chevy T and C Series
Diesel Engine 7.8L (6HK1) Equipped with Diesel Particulate Filter

2011-2015 N-Series Truck
Equipped with a 5.2L (4HK) or a 3.0L (4JJ1) Equipped with Diesel Particulate Filter

Isuzu trucks are equipped with a closed PCV system. The purpose of the closed PCV system is to keep harmful blow-by gas from entering the atmosphere. Unfortunately, blow-by gas production and air intake demands do not always match which allows oil vapor from the crankcase to enter the intake system. As a result of the closed PCV system allowing blow-by gas entering the intake system, there is a lot of unnecessary turbo replacements. Oil in the intake system is common with the closed PCV system and is not an indication of a bad Turbo.

Isuzu turbochargers are equipped with a dynamic seal (not rubber). Boost pressure on the compressor side and the exhaust pressure on the turbine side keep the lubricating oil inside the turbocharger center housing. A reduction in pressure on either side of the center housing will allow oil to pass into either the intake or the exhaust side of the turbo. When diagnosing oil in the engine complaint it will be necessary to determine the source of the pressure reduction.

Trucktechhelp has an information packet to aid in the locating the source of pressure reduction HERE.

One thought on “Isuzu Turbo Diagnostic Tips

  1. Marcos Gomez says:

    Greetings I work with a fleet of isuzo npr, nqr, I have some expectation about the operation of the diesel turbocharger in this case and detected large oil leaks, in the turbocharger system I know that it is recycled air from the manifol that quantity returns to admission but another part to the relief which goes through dpf the problem that causes me is not regenerating, take one to teller isuzo and they reported contamination in the dpf? How can I see that it is not a site from which it was designed, it is normal in the system.

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