Diesel World – October 2019

(Jacob Rumans) #1
Aftermarket injectors and high-pressure fuel pumps are sizable investments, especially
on common-rail engines, so take care that yours only see the cleanest fuel possible.
Changefuelfiltersanddrainyourwaterseparator(ifapplicable)everyotheroilchange,or
atleastoncea year.

After six years of loyal service, these Stage 4 hybrid 7.3L injectors were sent in to
Unlimited Diesel Performance for inspection and a refresh—and we’re glad we did it when
we did. Not that they were getting ready to fail, but some wear and tear was discovered on
the plungers during teardown, along with a few solenoids not passing spec and requiring
replacement.Thereis nowaytodiagnosethisotherthanpullingthemandsendingthe
injectorsin,astherewerenowarningsignsthattheywereinneedofsomeTLC.

Asyoucanimagine,performanceapplicationsareharderonvalvetraincomponents.Withaddedrpm,boost,
anddrivepressurein themix,valveadjustmentbecomesevenmoreimportant.Thisis especiallytruefor24-valve
Cumminsapplications.ManyDuramax-centricshopsbelievethatvalveadjustmentsshouldbecarriedoutany
timetheheadsareremovedorthevalvecoverspulled.

Though it’s a bit extreme for street-driven trucks, at the high-end of
diesel drag racing and truck pulling, it’s normal for engine builders to
take a peak inside of these monsters at least every other year, if not
every off-season. Thanks to stronger, deck-plated and billet-aluminum
blocks, these 3,000 hp behemoths have proven highly durable, with
many appearing brand-new inside after an entire summer of abuse.
However, new pistons or rings, a quick cylinder hone, or fresh bearings
provide good peace of mind for keeping these engines healthy. For
an engine that cost well north of six figures, the added insurance is
welcomed.

INJECTIONSYSTEM


ENGINE


The aforementioned Stage 4 hybrids were also fitted with brand-new
200-percent nozzles and flow-tested (350ccs) while in Unlimited Diesel
Performance’s care. There is no set timeline on when to replace injector
nozzles, but it’s important to know they too don’t last forever—or even
as long as a factory nozzle. This is because a larger hole size means
more meat has been removed from the nozzle itself. When you get into
competition-size nozzles (400-percent and larger), it’s not uncommon for
a nozzle to crack at some point.

Pulling the injectors on many engines allows you to take a look at
the rocker arms, inspect the injector wiring, test glow plugs (where
applicable), and even access your head stud nuts for a re-torque or
torque check. Again, just because you’ve added stiffer valve springs,
stronger pushrods, or even built the engine, it’s still wise to take a peak
inside the engine whenever (and wherever) possible, even if it’s part of a
separate repair or upgrade.

TECH BUILT TRUCK REFRESH

68 OCTOBER I 2019 • DIESEL WORLD http://www.dieselworldmag.com

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