In the next few installments , I am sharing "my all-time favorite technical article" submission to CC Destinations magazine as received from the engineering and service gurus at the former Country Coach Inc. This article was a 3 part work from the one and only Brian Keys. Brian worked as an Electrical Engineer and as a Service Manager during his tenure at CC. All Country Coachers who had the chance to speak with him about the inner workings of a Country Coach would agree the man was something of a wizard when it came to all things electrical. His knowledge pool was Deep! *Country Coach Destinations, was printed from 1995 through 2009 and I was blessed to be a part of creating every single issue, until the company closed its doors and "my adopted 4th child," Destinations print magazine, ceased its production.
Maintenance
Tips for the Mature CC Motorcoach - Part 1 of 3 by Brian Keys
Has your
coach passed its initial flush of youth? Are you apprehensive of system failures and large repair bills as
your coach enters its golden years? Many of
you have read about, discussed or experienced some of the problems
encountered by owners of older
coaches, but many of these problems are avoidable through preventative maintenance measures and a common sense approach to
whatever problem may arise. This
series of articles will focus on coaches that are five years or more in age, but the advice that
follows is also applicable to just about any Country Coach on the road
today.
FILTERS
Let us begin by taking a look at the various filters used
throughout your coach. We all know about the common filter replacements such as
the engine air, oil, fuel, and transmission filters, so no need to dwell on
these. Other filters that need to be replaced regularly are as follows:
~ Hydraulic System Filter(s).
These are located within the hydraulic oil reservoir just inside
the engine compartment opening. Coaches with a Gillig chassis will use a single
filter, while those with a DynoMax chassis will take three filters, stacked on
top of each other. The hydraulic oil itself must be replaced periodically also!
This maintenance item is often overlooked much like the brake fluid in your
car. However, the recommended service interval to change both the oil and the
filters is 25,000 miles or two years, whichever occurs first. While on the
subject of hydraulics, take some time to inspect the hoses that connect the
various hydraulic system components together such as the fan drive motor, fan
drive controller (FDCA), steering gear box, hydraulic pump, and the reservoir
itself. Look for any signs of chafing or loose/cracked fittings and repair as
necessary. All DynoMax coaches use proportional hydraulics for the hydraulic
fan, thus eliminating the system shock that can fatigue hose fittings through time.
~ Air System Filter/Dryer.
Your coach uses a desiccant cartridge to extract moisture from the
air system. This is critical to avoid corrosion, and to ensure continued
operation of all pneumatic valves and components should the ambient air
temperature drop below freezing. This desiccant cartridge is located inside the
Air Dryer assembly that is mounted either just forward of the drive axle, or
just behind the front axle. This device also contains the Purge Valve which is
responsible for the periodic ‘whooshing’ sound that comes from beneath your
coach as you drive. I recommend that this desiccant cartridge is replaced every
two years, or 50,000 miles, whichever occurs first. Overlooking this service
requirement will eventually lead to an extremely expensive repair bill to
extract the fine white powder released when an old desiccant cartridge
explodes. When it comes time to replace the desiccant cartridge, the Purge
Valve located at the base of the cartridge should be serviced also. A
maintenance kit is available for this valve which includes all the necessary
seals and springs etc. However, given the frequent cycling of this valve on
coaches with IR (Instant Response) Height Control Valves (HCV) such as all
DynoMax models, you should consider the more expensive but reliable option and
replace the entire Purge Valve assembly.
~ Refrigerant Filter/Dryer.
Speaking of expensive repair bills, another filter that is often
overlooked with dire consequences is the refrigerant dryer for your
air-conditioning system. This inexpensive filter (some coaches have two) is
responsible for removing any moisture from the refrigerant thus eliminating the
possibility of a frozen metering valve and the resulting loss of refrigerant
circulation. Filter replacement is mandatory if the system is opened to the
atmosphere either during service, or because of a major system leak such as a
hose failure. If this replacement is overlooked then the filter can fail,
filling the high pressure side of the system, including the condenser and the
metering valve, with small desiccant beads much like the expanded styrene
commonly used for shipping packages. Should this occur, the cost effective fix is to flush out the high
side hoses with water and blow them dry with air. The condenser and metering
valve should be replaced. Then, most importantly, every last trace of water
must be removed using a high vacuum pump and a micron meter, to evacuate the
system down to at least 400 microns. This will lower the boiling point of the
water to sub zero temperatures, allowing it to be removed as steam.
~ Coolant Filter.
This filter lives on the engine block with Cummins and Detroit
series 40 engines, and is mounted remotely for Caterpillar equipped coaches. It
serves two purposes, and these are to passively filter the coolant, and as a
means to add conditioning additives to the coolant as necessary. A fresh
coolant test strip that is compatible with the coolant used on your coach will
determine what level of additives are required, and this test strip should be
used on a coolant sample taken from the cycling engine circuit such as at a
radiator or engine drain. The long life coolants in use today do not eliminate
the need for coolant system maintenance, which is becoming increasingly
critical as the power output from modern diesel engines continues to rise. A
future Destinations article will go into detail on this important topic, but
until then, do not overlook this vital maintenance task. Does your coach have a
Hydro-Hot heater system? Then be aware that your coolant system requires a
special type of FDA approved non toxic coolant.
~ Generator Filters.
As with the engine on your coach, the generator will also require
periodic replacement of the air, oil and fuel filters. Propane powered
generators will not require a fuel filter. However, diesel generators do, and
this filter will cause some trouble due to algae growth in the diesel fuel if
the generator lies dormant for a prolonged period of time. If you remove the
fuel filter to find it full of a heavy green tinted liquid, then you are
probably not running the generator enough to ensure the fuel in the hoses
running to and from the diesel tank remain fresh. I recommend at a minimum that
the generator is run for at least two hours on a monthly basis. While the fuel
filter may require more frequent servicing due to stagnant fuel, the air and
oil filter can safely be replaced according to the generators maintenance
schedule.
~ Furnace Filters.
If your coach uses a diesel fired furnace for interior heat such
as the Webasto, Hurricane or Hydro-Hot, then there will be one or two filters
in the fuel system that must be replaced when servicing the furnace. This
service should occur annually before the cold season begins.
~ Water Filter.
Most owners are not foreign to water filters and their need for
periodic replacement based upon the volume of water used, but we do encounter
owners from time to time whom are unaware that their coach has a water filter
installed. If you have strong water pressure at your plumbing bay faucet, but
the pressure inside the coach is somewhat weak, then this is a good indicator
that the replacement of your water filter is long overdue. The filter housing
is typically located behind a labeled access panel in the plumbing bay itself,
or on the rear wall of the bay just forward of the plumbing bay. The filters
are readily available from hardware stores such as Home Depot etc, and you
should use an activated carbon filter to both remove particulates, and improve
the taste of your potable water.
~ Sediment Filter.
Does your water pump seem to have less output than before? While
water pumps do not last forever, take a look at the sediment trap that
separates the water pump from the fresh water tank before you replace the pump
itself. Cleaning this sediment trap may alleviate any inlet restrictions to the
pump that might exist, and give your system pressure a welcome boost.
~ Air Conditioning Filters.
The roof A/C’s on your coach include a removable, washable screen
to collect dust from the air as it enters the unit. This screen can be accessed
by removing the grille section from the roof A/C vent cover (no tools
required).
~ Cooling Fan Filters.
Last but not least, be aware that your coach may use a cooling fan
to cool an electronics cabinet or inverter compartment. These fans will
generally have a removable dust screen which should be cleaned periodically to
ensure the airflow is not restricted. Look for cooling fans in equipment
cabinets or consoles behind the driver’s seat, and in the inverter compartment.
Prevost Conversions with the ECC (or Electronic Control Cabinet) will also have
a cooling fan that discharges through the forward wall of the first bay into
the front axle area.
to be continued in another installment......
