Getting it down cold with preventative maintenance

It's that time of year again: The weather is turning cool, and the leaves are turning brown. This time of the year also spawns new challenges for coaches and their heating systems, as you ready them for winter. You'll want to service your air filters and air dryer; drain your air tanks daily; and, last but not least, service your auxiliary heater.

Routinely changing your air and fuel filters goes without saying. What goes more un-noticed is the servicing of the air dryer and the daily draining of the air tanks.

The air dryer is one of the most important parts of the coach air system and warrants special attention this time of year. If not properly maintained, it can freeze up and leave your coach literally out in the cold.

  • Change the air dryer desiccant cartridge and verify the air dryer heater function.
  • Remember to ice down the base to get the heater to sense a cold temperature and come on.
  • Check the operation of the purge valve; change if required, and adjust your air-pressure setting.
  • Drain your air tanks at least once a day. Water or oil in the system can cause the purge valve to stick open and prevent the system from building up necessary air levels.
  • Every 25,000 miles, use a measuring cup to check the wet tank for moisture levels.
> 2 oz Air dryer is working
> 2 oz; but < 3 oz Change dessicant cartridge
> 3 oz Change desiccant cartridge; check purge valve cycle:
  If purge valve cycle > 17 seconds, replace regeneration valve

For additional information, please refer to MCI Service Bulletins 2902C and 2974.

The time is now to make sure your auxiliary heater is clean and working properly. Let's be honest — no one enjoys rolling around in the cold and snow working on a heater when it could easily have been done while the weather was still nice.

Proheat recommends regular operation of the unit throughout the year to improve reliability, and suggests at least weekly use. The Proheat® X45 unit is electronically controlled and monitors itself during operation. Normal operation and malfunctions are indicated on the controller face with a series of LEDs that illuminate to aid the technician in diagnosis, or a digital readout on the latest controller. Routine maintenance is necessary to keep the Proheat unit in proper operating condition. In addition to regular daily inspection of hoses and connections, an operator should run the heater through a complete cycle at least once a week to keep fresh fuel in the heater's critical components. Proheat recommends a maximum of B5 for bio-diesel. Also see MCI Service Bulletin 2913 for seasonal maintenance information for the X45 Pro-Heater

The best time to perform annual maintenance is prior to the onset of your area's heating season. Here are the manufacturer's recommendations:

  1. Clean heater enclosure
    • Remove the heater enclosure and blow out the compartment with compressed air. Clean any accumulated debris or dust from the components. Make sure the opening around the exhaust pipe is clear. Visually inspect all components for wear or damage.
    • Clean the flame sensor.
    • Clean the sight glass using a clean cloth and standard window cleaner.
  2. Maintain your heat exchanger. To maintain optimum heat output, clean any combustion deposits that may have accumulated on the heat exchanger fins.
  3. Check the exhaust system carefully. Make sure the exhaust pipe is vented safely. Check for dents, restrictions or severely corroded areas. Replace the exhaust pipe and clamps if needed. Ensure that the exhaust pipe clamp is tight.
  4. Electrical system check: Check the internal and the external wire harness for damage. Replace if required.
  5. Clean air intake: Check the combustion air inlet screen for restrictions. Clean as required.
  6. Fuel system: Check the fuel system for damaged fuel lines or leakage. Make sure the clamps on the fuel lines are secure.
  7. Vehicle batteries: Check the condition of the batteries and power connections. The heater will not function properly with weak batteries or corroded connections. If you are unsure of their condition, load-test each battery separately and replace as required. Clean terminals to remove all corrosion.
  8. Operation test: Run the system for at least 15 minutes or until the heater cycles "OFF" and then "ON" again.

In addition to the dryer and auxiliary heater, some often overlooked, but still important, seasonal-change areas to also address are:

Air Lines, tanks and valve

Throughout the year, some moisture and oil are destined to escape the dryer and get into the air system. This is evident when periodic draining of the service tanks yields water and debris, which inevitably migrates into the lines and valves. Flushing all of the air lines and valves can eliminate any ice-related extreme-weather problems. Service Bulletins 2811 (D coach) and 2812 (E/J coaches) outline the procedures for checking correct brake system operation and draining the air tanks.

Engine thermostats and coolant:

After making sure that the hot water valves are open (they shouldn't be shut in the first place), the most common complaint of poor heat often stems from the lack of operating temperature in the engine. Beyond supplying a comfortable level of heat to your passengers during those chilly winter treks, a hot engine runs cleaner both internally and externally, and generally uses less fuel. An unusually long warm up period or simply not getting to a normal (195° Fahrenheit) temperature is a sure sign that the thermostats may need attention.

Engine heating and cooling over time also causes the coolant additives to degrade and quantity levels to drop, adversely affecting coolant performance and potentially damaging the cooling system and engine. These additives can be restored by replacing the supplemental coolant additives. By performing periodic coolant sampling and testing, the additive levels can be monitored and modified accordingly. Always test the antifreeze solution before adding water or antifreeze, using a standard antifreeze tester (hydrometer or refractometer) approved by the engine manufacturer. All engine manufacturers have recommendations or requirements for the antifreeze used in their engines. To test the coolant, the coolant should be slightly warm. Fill and empty the tester several times to pre-heat it before making that actual test. Make sure to keep the testers clean, inside and out.

Batteries and charging system:

Last but not least is the battery itself. Batteries are being made with better, more durable materials then ever before. They last longer than ever, but they are still lead-acid batteries, and maintenance is just as important as ever. Batteries can last a long time if you take care of them, but don't ignore the battery box, or it's going to make your life a lot more complicated than it needs to be.

Cold cranking amps is a commonly overlooked specification for batteries, but basically is a test for the batteries' ability to deliver good power to the starter during freezing temperatures. As a battery ages, the plates' ability to create electrical energy is reduced and they may not be able to perform well on a cold morning. A comprehensive test of batteries and charging system can help you avoid surprises in the waking hours before a tour. Load testing the batteries is the recommended way to know that your batteries will be able to perform as expected (see section 7 in the maintenance / service manual for your MCI coach.)

This is also the time to perform a comprehensive test of the charging system, including cables and connections, to make sure the alternator(s) can keep the batteries at the peak of their capability.

Performing a few simple steps may take and hour or two of shop time but remember that it is called PREVENTATIVE maintenance for a reason. A few hours in your shop will always be better than a middle of the night or early morning road call.

If you have additional questions on coach winterization, consult your nearest MCI Service Center, or call MCI Technical Support at 800-241-2947.

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