Wednesday, April 22, 2009
INFORMATION ON NEW DIESEL ENGINES: THINGS TO LEARN
By the Workhorse Technical Team
As new diesel emissions technology develops, motorhome owners have new things to learn. There is one set of new warning lights for particulate buildup that it is especially important for those driving new diesel Class As to monitor — or risk damaging their engine.
Workhorse Custom Chassis, a leading manufacturer of chassis for Class A motorhomes, has noticed instances of driver failure in this regard. Unfortunately, when this happens there is no warranty coverage for repairs and towing, not to mention the potential hazard to the driver and others. So it pays for drivers to read the manual and pay attention. They need to know what their gauges and warning lights mean.
All diesel engines produced after Jan. 1, 2007, must comply with the new regulations requiring the reduction of nitrogen oxide (NOx) and hydrocarbons (HC) by 50% and particulate matter (PM) by 90-plus percent over the previous 2004 emission standards. To reduce particulate matter, a Diesel Particulate Filter (DPF) is used on all Class A diesel motor homes.
The DPF captures soot and larger sulfate particles in a series of ceramic honeycomb channels as gas passes through the porous material, and the particulates are trapped and accumulate on the channel walls. After thousands of miles, the DPF will eventually become clogged if nothing is done.
To prevent the DPF from clogging, the trapped particulates are burned off, and the filter is cleaned using a high temperature (around 1,700 degrees Fahrenheit in the Particulate Filter) regeneration process that leaves a harmless ash and residue. There are different regeneration processes for different diesel platforms, including automatic regeneration, manual regeneration, and DPF removal for an exchange or off-vehicle regeneration.
Workhorse’s new W16D, W20D and W22D chassis with MaxxForce diesel engines are examples of how both manual and automatic regeneration are used. The driver must monitor a series of instrument cluster system lamps that indicate various levels of low to full soot load with the DPF as determined by engine exhaust back pressure. For motor home owners who drive their rigs mostly at highway speeds, automatic regeneration will kick in. However, if much low speed driving occurs, manual regeneration may be needed.
For this typical system, there are four levels of warning indicators that signal potential hazards and the action needed:
First Level — Low soot load buildup: requires the driver to get up to highway speed to engage the automatic regeneration or to safely pull over and engage in manual Parked Regeneration.
Second Level — Exhaust filter is full: requires the driver to safely pull over and begin Parked Regeneration to prevent loss of power
Third Level — Exhaust filter is full and engine performance is limited: Driver needs to safely pull over and begin manual regeneration to prevent engine shutdown.
Fourth Level — Soot overload: a serious engine problem has occurred and the engine may shutdown soon. Safely pull off the road, turn on flashers, place warning devices and stop engine. DO NOT USE Parked Regeneration but call for service.
Manual Parked Regeneration is a simple process of hitting a switch that increases the engine speed to a set RPM that achieves the temperature needed to burn off the soot. Needless to say, this will make the exhaust very hot, so the driver needs to take care to park away from people or combustible materials and vapors. This process takes about 30 minutes. To thoroughly clean the DPF system, the motor home should also be run at highway speeds for 20 minutes after a manual regeneration.
As we mentioned, this soot buildup happens over thousands of miles, so the regeneration process does not happen very often to the typical motor home owner. However, if the warning lights do go on, it is very important that drivers know what to do if they want to avoid crippling their rig with serious engine damage.
For more information from Workhorse service, call 877.294.6773 or visit www.workhorse.com.
Monday, April 20, 2009
RECALL: 2008-2009 TIFFEN MOTOR HOMES: ALLEGRO BUSES: ANITLOCK BRAKING
TIFFIN / ALLEGRO BUS 2008-2009
Manufacturer: TIFFIN MOTORHOMES, INC. Mfr's Report Date: APR 15, 2009
NHTSA CAMPAIGN ID Number: 09V127000 NHTSA Action Number: N/A
Component: SERVICE BRAKES, HYDRAULIC:ANTILOCK
Potential Number of Units Affected: 329
TIFFIN IS RECALLING 329 MY 2008-2009 ALLEGRO BUSES. THE REAR AXLE ABS MODULATING VALVE HAVE THE POTENTIAL TO BE WIRED INCORRECTLY. THE RIGHT AND LEFT MODULATOR VALVE HARNESS PIN COULD POSSIBLY BE REVERSED AT THE ABS ELECTRONIC CONTROL UNIT (ECU) CONNECTOR.
UNDER SLIPPERY ROAD CONDITIONS, WHEN IN THE ABS MODE, THIS WIRING PROBLEM HAS THE POTENTIAL TO CAUSE ONE SIDE OF THE REAR WHEELS TO LOCK WHILE CAUSING LITTLE OR NO BRAKING EFFORT ON THE OPPOSITE SIDE. THIS MAY RESULT IN A LOSS OF CONTROL AND A VEHICLE CRASH.
DEALERS WILL REMOVE THE REVERSED PINS FROM THE ECU CONNECTOR AND INSERT THEM BACK INTO THEIR CORRECT POSITION FREE OF CHARGE. THE RECALL IS EXPECTED TO BEGIN DURING APRIL 2009. OWNERS MAY CONTACT TIFFIN AT 256-356-8661.
OWNERS MAY ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY 1-800-424-9153), OR GO TO HTTP://WWW.SAFERCAR.GOV .