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SCCA Magazine March-April 2010 |
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What to expect from the latest
on-road enginesAn unprecedented number of
on-highway engine changes and new technologies
have been introduced in the last few years as
manufacturers struggle to meet the emissions
mandates of the Environmental Protection Agency
(EPA) and the California Air Resources Board
(CARB). The changes have not come without their
difficulties. Most have been kept in-house
under warranties – problems with exhaust gas
recirculation (EGR) systems, turbochargers,
diesel particulate filters, etc. – and kept as
quiet as possible as solutions are sought and
in-production fixes are instituted.
The
problems
Cummins – According to technicians,
maintenance managers and service managers,
different engines have different issues. Cummins
engines have had troubles with the EGR valves,
as evidenced by the different locations with
each generation of the ISX. In the earliest EGR
engines, the valve was located on the hot side
of the engine. For 2007, it moved to the
opposite side of the engine but by all accounts
this has not eliminated all problems with the
valve. So for 2010, there is a complete redesign
in how the valve works.
Early in the evolution of EGR on the Cummins
15-liter, one fleet service manager told me they
had great success in dispensing with the EGR
valves altogether and running the engines
without the backflow of exhaust. This of course,
is not how the system was designed to work and
they were running out of emissions compliance.
But, he said, at least they were running. The
ISX has also had turbocharger issues, reported a
senior diesel mechanic with a large dealership.
In the early days of the 2007 engines, I can
personally report that a turbocharger failure
put me at the side of the road for eight hours
waiting for a tow truck.
Mack – In the last
days of the Mack E7, the turbochargers were the
weak point in an engine that had enjoyed a great
reliability record. One Mack engineer said at
one point the E7 was taken one generation too
far in its development and the turbocharger was
a major issue. Mack eventually addressed the
issue with a total redesign of the turbo on
behalf of its supplier. And the change to the
Mack version of the Volvo D12, D13 and D16
engines has ended that problem.
Caterpillar –
The engines that are seeing huge failures of
turbos now are the complex Caterpillar series
turbocharged engines. One mechanic I interviewed
said this is an ongoing issue, and he and his
colleagues were getting really good at
installing a replacement low-pressure turbo.
Other issues are downstream of the turbo, and
coking of the poppet valve, spark plug issues
and other combustion problems have bedeviled the
post-2007 Cat engines. Fuel economy has also
been an issue with the post-2007 Cats, but that
is largely because the top end of the specific
fuel curve shoots upwards so they have to be
driven keeping maximum rpms below 1350 – hard
for many drivers to do.
Users continue to complain about the poor
performance and rough running of the C15. The
general consensus is that it is particularly
sensitive to fuel filters – anything not genuine
Caterpillar will likely starve the engine of
fuel and counterfeit C15 fuel filters are
plentiful.
Volvo – New engines that are doing
well for Mack seem to be doing equally well for
Volvo. Hardly surprising – under the valve
covers, the engines are basically the same.
(Mack’s MP6, MP7 and MP10 represent displacement
in hundreds of cubic inches, while Volvo’s D12,
D13 and D16 are displacements in liters.)
These engines would appear to have had a
relatively untroubled launch. But the earlier
Volvo engine, the VE D12, an altogether
different engine, has its share of issues with
EGR. It uses an exhaust pulse generator to pump
the exhaust gas into the inlet manifold against
the turbocharger pressure, dispensing with the
complexity of the variable geometry turbocharger
that was such a trial for Mack. There have been
failures of this dual-flow EGR cooler and EGR
valve problems.
Detroit Diesel – Detroit’s
DD13 and DD15 appear to have had nearly a
faultless launch, but there are issues with the
Series 60 that ended production with launch of
the 2010 engines. One problem is accelerated
ring and liner wear on the rear cylinders of EGR
engines. The symptom is a rapid rise in the use
of engine oil that means a lot of add-oil on
this normally dry engine. Series 60 owners might
consider a Sanco Filters solution that places an
EGR filter in the crossover pipe from the EGR
valve to the inlet manifold.
Other Series 60 issues have to do with injector
tubes letting fuel and coolant mingle. The
solution is a Reliabilt reman head from Detroit
Diesel. Some users report fuel pump, sensor and
ECM problems on their 60s. The ECM connectors
are a possible source for rough running and
missing. One suggestion is to disconnect the
connectors and look for corrosion of the pins.
Cleaning everything and using dielectric grease
is a possible cure. Another cure for rough
running may be replacement of the TRS and SRS
sensors that measure the engine timing and
piston position. They are located behind and
below the air compressor and can be at the point
of failure and still not throw a fault code.
Scorecard for 2007 engines
The
Technology and Maintenance Council of the
American Trucking Associations (ATA) has been
keeping an eye on the 2007 engines. Reports on
how the engines are performing show the level of
satisfaction has improved as faults and fuel
economy issues have been chased down by engine
manufacturers.
“With 2002 engines there
was a high failure rate on the first engines,
with unreliable EGR systems and components,”
says Dan Umphress, managing director of
maintenance solutions for FedEx. “They took a
16-percent fuel economy hit but that quickly
narrowed to 3 percent. Drivers love the
performance of the EGR engines. The 2007 engines started out with the same fuel
penalty but improved with fine-tuning. Drivers
had to be educated about new warning lights and
active regenerations on these engines. Early in
the introduction, the engines are much more
reliable than the 2002s and 2004s.”
Frank Nicholson, vice president of maintenance,
TransAm Trucking, says the 2007 “clean-air
induction” Caterpillars have been plagued with
recalls. “Parts availability is a constant
issue,” he says. “Overall durability is down and
downtime is up 125 percent. Maintenance cost has
increased 37 percent in parts costs with a 50
percent increase in labor costs.”
According to Steve Duley, vice president of
purchasing for Schneider National, most defects
with the 2007 engines related to aftertreatment
dosers, sensors and injectors. “We switched to
the more expensive CJ4, but oil consumption has
been very good at 7,000 miles per quart,” he
says. “Overall, the 2007 engines’ lifetime cost
is double that of the earlier EGR engines.”
For Curtis Cummings, project manager, Power
Vehicles FedEx Freight, most issues with the
2007 engines have been with diesel particulate
filters. More than 100 had to be cleaned because
aftertreatment injector failure clogged the
filter. “EGR valves and coolers remain a
concern,” he says, “but the trucks perform well
and drivers are really positive.”
Cummings says durability has improved and cost
per mile has decreased over time by 51 percent.
There’s a reduced fuel economy penalty of 1.8
percent but the overall experience is “very
good.”
“At the beginning of the 07s,
regenerations were an issue as the engines did
not run hot enough for passive regeneration,”
says Dan Miller, manager equipment
processes/reliability for YRC Worldwide. “We had
to program for regeneration when trucks were
parked.” The YRC fleet has also had issues with
the 7th injector (aftertreatment doser) and
added a cleaning at the 70,000 mile PM interval.
Fuel economy has suffered, he says, and they’ve
tried to offset the penalty with fuel-efficient
tires.
“Training technicians to deal with the 07s is
absolutely required,” says Miller.
–By Steve
Sturgess
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