Fleet Maintenance - 46


How much do you spend
on DPF maintenance?
Many fleets don't know the steps they can
take to help improve fuel economy and engine
performance, such as engine pre-conditioning.
A recent fleet study by Webasto Thermo &
Comfort North America, in conjunction with
Fleet Maintenance magazine, found that 87
percent of those surveyed did not know how
much their fleet was spending annually on
diesel particulate filter (DPF) cleaning.
Perhaps more alarming was that 65 percent
of respondents reported not knowing how
much their fleet was spending annually to
replace damaged and inoperable DPF filters.

An overview of the DPF
» Fuel-operated
heater solutions, like
Webasto coolant
heaters, have been
used to pre-heat
engines in order
to minimize cold
startup emissions,
reducing DPF
costs and vehicle
downtime, while
improving fuel
economy and overall
engine performance.
Photo courtesy of Webasto

A DPF device is deceptively simple in concept,
yet it operates in a complex environment.
The DPF is designed to trap soot and particulate matter (PM) from a diesel engine's exhaust
gas so it is not released into the atmosphere.
After engine combustion, exhaust gas is directed through a ceramic filter substrate.
The filter traps soot and PM, while deposits of
these materials form on the walls of the filter.
When the collected material reaches a pre-determined level, sensors monitoring back-pressure
activate the filter regeneration process.
The regeneration process occurs automatically when the engine is operating at high
temperatures, with the catalyst converting soot
and PM materials into ash. The ash deposits are


» For coolant heaters, Webasto's SmarTemp
Control fx 2.0. features programmable
run times and system diagnostics.
Photo courtesy of Webasto

stored in the filter cavities for later extraction
through routine cleaning in the shop. The
frequency of the DPF cleaning intervals is
directly proportionate to engine condition
and duty cycle.

Effects of cold-start events

In a cold-start scenario, the DPF's catalyst is
too cold to perform its regeneration function.
An engine that starts cold will emit un-combusted fuel and PM into the DPF, resulting
in a heavy, wet, and dense soot buildup that
increases back-pressure. This can result in
reduced engine and DPF efficiency. Face plugging and filter overload often result. Cold starts
also create the need for more frequent DPF
cleanings, which shorten DPF effectiveness
and, ultimately, lifespan.
Factor in downtime for cleaning DPFs and
replacement costs can range between $2,500
to $8,000 per vehicle.

Impact of high-idle run times

Idle time represents as much as 50 percent of a
vehicle's run time for some markets. All those

By Duane Bratvold

The Webasto Group product portfolio comprises a broad range of roof and heating systems for
every type of vehicle and all drive types as well as battery systems and charging solutions. Bratvold
uses his expertise in emissions standards to provide fuel-operated heaters and other emissions
management solutions for fleets of trucks, buses, and off-highway equipment. He serves as
Webasto's corporate expert on emissions and is respected within the commercial vehicle industry
for his vast knowledge and 36 years of experience within the diesel emissions sector.

46 Fleet Maintenance | May 2019

non-productive hours translate into a lot of
wasted fuel and a tremendous overhead cost
for fleets. According to the U.S. Department of
Energy, a long-haul truck idles about 1,800 hours
per year, using about 1,500 gallons of fuel.
An idling engine is terrible for a DPF. In fact,
until the DPF is operating at between 842 to
1,112 degrees F (450 to 600 degrees C) - generally at road speeds - it's using its DPF as a virtual garbage can for the collection of soot and PM.
Just as in cold-start events, excessive engine
idling allows the exhaust, and thus catalyst,
temperatures to drop below their optimal
levels, causing the DPF to lose efficiency. At the
same time, PM emissions from the cooler engine
increase, causing the DPF to be overwhelmed.

Pre-heating or pre-conditioning a diesel engine
with a fuel-operated heater (FOH) warms the
engine and its fluids to about 165 degrees F
before the engine is ever started. These devices
operate on diesel fuel drawn directly from the
vehicles primary fuel tank.
FOH pre-heaters save fuel by reducing idling
time, warming engines so they start more easily, and by eliminating long engine warm-ups.
In addition, one of the most important things
FOHs do is reduce maintenance costs as a
byproduct of reducing the burden on emission
control devices, like DPFs.
Coolant heaters have been proven to reduce
cold, dense soot by up to 66 percent during
engine startups, while also reducing nitrous
oxide emissions by up to 40 percent, according
to independent lab testing referenced in TMC
RPs 432 and 1102.
By raising the initial engine temperature at
startup, these devices can help reduce the time
it takes for the DPF to become active, reducing the "wet stacking" often produced by cold
engine starts.
With pre-heating the entire power unit,
engine oil is warmer, sealing piston rings and
diminishing engine blow-by, while decreasing
the amount of "carry over" oil in the exhaust
stream. Warmer injectors increase fuel efficiency, and diesel exhaust fluid (DEF) tanks
and injectors are also protected from freezing
in cold climates, thus increasing their overall
efficiency and reliability.
By minimizing the wet, dense soot and PM
emissions associated with cold engine starts,
pre-conditioning reduces filter overloading and
face plugging, and significantly increases the
time between cleaning intervals.
When drivers start a pre-heated engine,
they also immediately get warm air from the
HVAC system.
A number of FOH products are listed under
the "Verified Idling Reduction Technologies"
category by the U.S. Environmental Protection
Agency SmartWay Program. Coolant heaters
are extremely fuel efficient in helping achieve
optimal engine starting temperatures while
reducing engine wear, fuel consumption, and
exhaust emissions. An engine pre-heater also
delivers a fast ROI in the form of reduced DPF


Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance

Uptime - Are You Communicating with Employees Effectively?
Trends in Heavy Duty Diesel Engine Oils
Vehicles - Keys to Consistent Liftgate Performance
In the Bay - How Standardized Vehicle Communication Protocols Impact Diagnostics and Vehicle Operation
Shop Operations - Considerations for Mobile Device Usage in the Shop
Training - Where are all the Students Going?
Management - Why the Recent Airline Accidents Should be Concerning
Fleet Parts & Components
Tools & Equipment
Guest Editorial - How Much Do You Spend on DPF Maintenance?
Fleet Maintenance - 1
Fleet Maintenance - 2
Fleet Maintenance - 3
Fleet Maintenance - 4
Fleet Maintenance - 5
Fleet Maintenance - 6
Fleet Maintenance - 7
Fleet Maintenance - Uptime - Are You Communicating with Employees Effectively?
Fleet Maintenance - 9
Fleet Maintenance - Trends in Heavy Duty Diesel Engine Oils
Fleet Maintenance - 11
Fleet Maintenance - 12
Fleet Maintenance - 13
Fleet Maintenance - 14
Fleet Maintenance - 15
Fleet Maintenance - 16
Fleet Maintenance - 17
Fleet Maintenance - Vehicles - Keys to Consistent Liftgate Performance
Fleet Maintenance - 19
Fleet Maintenance - 20
Fleet Maintenance - 21
Fleet Maintenance - In the Bay - How Standardized Vehicle Communication Protocols Impact Diagnostics and Vehicle Operation
Fleet Maintenance - 23
Fleet Maintenance - 24
Fleet Maintenance - 25
Fleet Maintenance - 26
Fleet Maintenance - 27
Fleet Maintenance - Shop Operations - Considerations for Mobile Device Usage in the Shop
Fleet Maintenance - 29
Fleet Maintenance - 30
Fleet Maintenance - 31
Fleet Maintenance - 32
Fleet Maintenance - 33
Fleet Maintenance - Training - Where are all the Students Going?
Fleet Maintenance - 35
Fleet Maintenance - Management - Why the Recent Airline Accidents Should be Concerning
Fleet Maintenance - Fleet Parts & Components
Fleet Maintenance - 38
Fleet Maintenance - 39
Fleet Maintenance - 40
Fleet Maintenance - Tools & Equipment
Fleet Maintenance - 42
Fleet Maintenance - 43
Fleet Maintenance - 44
Fleet Maintenance - Classifieds
Fleet Maintenance - Guest Editorial - How Much Do You Spend on DPF Maintenance?
Fleet Maintenance - 47
Fleet Maintenance - 48