Friday, August 27, 2010


Many times we forget that even though we live in an age that nothing seems impossible, some things as far as motor home enthusiasts are concerned are not possible. One of those things is cooling performance of an absorption unit versus the compressor driven unit that you may have in your home.

The absorption units that are in most motor coaches are in fact designed to conserve as much energy as possible. But, they also perform very well when properly maintained. While “camping” is not what it used to be, it is now a word that is all but obsolete with the luxuries that time has afforded motor coach owners. For a motor coach to be completely self sufficient, there is a need to conserve on board resources as much as possible, hence the need for a refrigerator that can operate on two or three different sources efficiently.

The refrigerators that are in coaches today are a much more sophisticated machine than the compressor driven units we have at home, where you plug them into an isolated 15-amp 110VAC circuit. These home units are very power-hungry as compared to the units you have in your motorhome. When running on AC voltage, absorption units only draw about 2.5 to 3.0 amps. The absorption unit actually extracts the heat from inside the food compartment slowly. Once the heat is removed, all that is left is cooler air.

There are a few simple steps that can help you get the most out of your refrigerator.

1. Start the refrigerator the day before it is to be filled with food.

2. When the refrigerator is being filled when preparing for a trip, the frozen foods should be pre-frozen before placing them in the refrigerator. Ice making should be avoided until the refrigerator has cooled the lower compartment to the desired temperature.

3. Air circulation within the food compartment is important for proper cooling. DO NOT place paper on the shelves or overfill the compartment with large cartons, etc.

4. Do not put hot food in the refrigerator. Allow it to cool to room temperature first.

If you believe your unit is not cooling as it should, one check you can perform is to check the doors for proper sealing. A simple method of doing this is to close the door on a dollar bill, then pull the bill out. If no resistance is felt, the gasket is not sealing properly. This should be done on all four sides of the door (complete length of the gasket). Also check the rear of the unit for any blockage by opening the side vent and look all the way up the rear of the unit to make sure you haven’t got any stowaways such as birds and their nests. If you are not able to see all the way to the roof vent, then remove the roof cover and check the back of the unit as well. Drafting in the rear of the unit is very important for a proper cooling refrigerator.

To test the unit for proper cooling, place a thermometer in a small container of water and place in the center of the main storage compartment. Set the thermostat to it’s maximum position, close the door and run unit on AC power for 10-12 hours, check the thermometer at the end of this period you should have a reading of 36-42 F. If you do not get this temperature then you should contact your nearest service center for repairs.

Also the burner assembly and the flue should be checked and cleaned annually.

Foretravel Alternators and Isolated Battery Charging

Foretravel coaches are equipped with what are termed “externally excited” alternators.

These are not the same alternators used in the large trucks that run on our nation’s highways.

This fact is often misunderstood in a majority of large truck repair shops. Often

Foretravel customers must utilize these shops when they experience charging problems

on the road. Most of these truck repair facilities are only familiar with what are termed “internally excited” alternators which maintain a single bank of batteries (12 volt supplied to the large output post continually).

Foretravel, as well as other coach manufacturers, utilize a battery isolator in the alternator charging circuit. The alternator must be able to maintain two separate banks of batteries, one bank for the house batteries and one bank for the engine batteries, at a particular set voltage.

When a battery isolated system is used, the alternator has to be turned on, excited, from an ignition source. That process is termed “externally excited”. During testing with the main engine not running, there will be no voltage is present on the large positive output terminal of the alternator.

The alternator that Foretravel employs has two large terminals, one positive and one negative, on the back, as well as two small terminals. The two small terminals tell the voltage regulator what to do. One small terminal is labeled DUVAC and the other small terminal is labeled IGN.

The DUVAC terminal monitors (senses) the output voltage. The sensing wire runs from the DUVAC terminal directly to the engine battery side of the isolator on 2000 year model Foretravel’s to present. Earlier models sensed from the remote start panel.

The IGN (ignition) terminal turns on (excites) the alternator to start charging. This circuit is powered up when the ignition key is turned on. The only way the ignition terminal voltage will affect charge output voltage is if no voltage is present. It takes minimal voltage to start the alternator charging (7-7.5 VDC).

When checking the output voltage directly at the alternator while the alternator is charging, the output voltage will read higher than at the batteries. This is because there will be approximately a 1 volt drop from the output terminal of the alternator to the actual charge voltage at the engine battery terminal. This drop occurs in the isolator and associated wiring to the batteries.

Example: When reading the output voltage at the alternator with fully charged batteries and a properly functioning alternator, your readings should be approximately 15 volts dc (+/-), this in turn will allow for a maximum voltage at the batteries to be 14.1 vdc (batteries allowing for a normal 1volt dc drop in voltage through the isolator).

Checking Transmission Fluid Level from the Cockpit

With your Foretravel you are able to check the transmission fluid directly from your pilot seat. Allison Motorhome Series transmissions have an oil level sensor (OLS) that allows the operator to obtain an indication of fluid level from the shift selector. It is important that the proper fluid level in your transmission be maintained at all times because the transmission fluid cools, lubricates and transmits hydraulic power.

In later models there will be two types of push button shift selectors, the WTEC III or the Allison 4th generation (for information on earlier models shift selectors contact Foretravel Technical services).

WTEC III Controls displays fluid level Allison 4th Generation Controls displays

diagnostic information one character at fluid level diagnostic information two

a time. characters at a time.

1) Park the vehicle on a level surface, shift to N (Neutral), and apply the parking brake.

2) On the push button shift selector simultaneously press the↑ (Up) and ↓ (Down) arrow buttons.

NOTE: The fluid level check may be delayed until the following conditions are met:

• The fluid temperature is above 140°F and below 220°F.

• The transmission is in N (Neutral).

• The engine is at idle.

• The transmission output shaft has stopped.

• The vehicle has been stationary for approximately two minutes to allow the fluid to settle.

A delayed fluid level check for transmissions with WTEC III controls is indicated by a (-) DASH in the display window followed by a numerical countdown. The countdowns start at 8, indicates the time remaining in the two minutes setting period. The delayed indication for Allison 4th Generation is indicated by a flashing display under SELECT and a digit countdown from 8 to 1 above MONITOR.

• Correct Fluid Level – “o L” (represents “Fluid (Oil) Level Check Mode”) followed by “o K”. The “o K” indicates the fluid is within the correct fluid zone. (The OLS display and the transmission dipstick may not agree exactly because the OLS compensates for fluid temperature.

• Low Fluid Level – “o L” followed by “L o” (represents “Low Oil Level”) and the number of quarts the fluid is low. Example: o L L o 0 2 indicates fluid is low by 2 quarts.

• High Fluid Level – “o L” followed by “H I” (represents “High Oil Level”) and the number of quarts the fluid is high. Example: o L H I 01 indicates fluid is above the full level by 1 quart.

Any temperature below 140°F or above 220°F will result in an Invalid for Display condition. See your Allison Operator’s Manual for more info on this condition and complete details on checking transmission fluid.

Driving Tips with your Allison Automatic Transmission

Highway Driving


Operating in the “Drive” mode is recommended for normal driving conditions to reduce engine RPM for maximum fuel economy. Your Foretravel is equipped with an Allison Transmission with a secondary shift schedule option “mode selection button”, the mode should be “ON” for secondary mode versus “OFF” for the primary mode.


Mountainous Driving (Up & Down Terrain)


Manually pre-select a lower gear in order to maintain engine speed within a range of 500 RPM of engine governed speed. Road speed may decrease but power (torque) will remain at peak output while ascending a grade. When descending a grade, never use a higher gear than was used climbing that same grade. The selection of a lower gear will also minimize cycling between a gear and the next gear on a series of short up & down hills.


City Driving (Stop & Go Traffic)


Select the highest range that will allow the vehicle to reach the speed you expect to maintain between stops. This will minimize cycling between a gear and the next higher gear while driving in stop & go traffic conditions. When traffic conditions return to normal, move the selector back to the DRIVE position.


Driving on Ice or Snow


If possible, reduce your speed and select a lower gear before you loose traction. Select the gear that will not exceed the speed you expect to maintain. Accelerate or decelerate very gradually to prevent loosing traction. It is very important to slow gradually when a lower gear is selected. It is important that you reach the lower gear selected before attempting to accelerate. This will avoid an unexpected downshift during acceleration.


Engine Braking


To use the engine as a braking force, select the next lower gear. If the vehicle is exceeding the maximum speed for this gear, use the service brakes to slow the vehicle. Engine braking provides good speed control for going down grades. When the vehicle is heavily loaded, or the grade is steep, it may be desirable to pre-select a lower gear prior to the grade. The transmission control system will inhibit a shift into any range at a speed that will cause engine over speed. Any lower forward range may be selected at any time, but the actual engagement will not occur until road speed is reduced – downshifting is progressive as road speed decreases. The inhibit effect will cause downshifts to occur at slightly higher speeds than normal automatic downshifts.

Battery Types

The two battery types that have been used in your Foretravel house system over the last decade or so are Valve Regulated Lead-Acid (VRLA). Commonly known as either a gel (Gelled Electrolyte) or an AGM (Absorbed Glass Matt).

How does a VRLA battery work?

A VRLA is a “recombinant” battery. This means that the oxygen normally produced on the positive plates of all lead-acid batteries is absorbed by the negative plates. This suppresses the production of hydrogen at the negative plate. Water (H2O) is produced instead, retaining the moisture within the battery. It never needs water and should never be opened as this would “poison” the battery with additional oxygen from the air.

How are a gel battery and an AGM battery similar?

Both are lead-acid storage batteries that:

• are sealed using special pressure valves and should never be opened.

• are completely maintenance free other than the connections should be retorqued and the battery exterior cleaned periodically.

• uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in flooded lead acid battery (particularly in deep cycle applications).

• are non spillable, and therefore can be operated in virtually any position. However upside down is not recommended.

How are a gel battery and an AGM battery different?

• an AGM is an electric storage battery that has its entire electrolyte absorbed in separators consisting of a sponge-like mass of matted glass fibers.

• a gel battery uses thixotropic gelled electrolyte. (sometimes fluid and sometimes gel: becoming fluid when shaken or stirred and returning to a gel state when allowed to stand)

• Both are considered as “acid starved”. This condition of both protects the plates during heavy deep-discharges. The gel battery is more starved, giving more protection to the plate; therefore it is better suited for super-deep discharge applications.

• Due to the physical properties of the gelled electrolyte, gel battery power declines faster than an AGM battery as the temperature drops below 32°F. AGM batteries excel for high current, high power applications and in extremely cold environments.

Cold Weather Operational and Storage Tips

Whether your coach is to be used during the winter months or put up for storage, the chance it will be exposed to freezing temperatures or inactivity requires some preparation and maintenance attention.

Operating Coach in Cold Weather:

It is important to understand the interior water lines, fixtures, supply tank, pump and appliances are normally protected from moderate freezing temperatures, as long as the furnace remains in operation. Please keep in mind that your Motorcoach was not designed for prolonged use in sub freezing temperatures without implementing special precautions.

• Heating your coach requires an adequate supply of L.P. or diesel. Fuel tanks should remain as full as possible for extended cold weather trips.

• Pre-Heat your diesel engine before starting if it has cooled down overnight.

• When camping during cold weather select a sunny campsite over a shady one, near a wind break if possible.

• Park with either the front or rear of the coach into the wind if possible.

• Make reservations ahead to make sure the campground of preference is open.

• It is recommended that once each week both engine and coach batteries be fully charged. This is especially important in colder climates, due to their nature, batteries will eventually discharge if not used and recharged on a regular basis; also resistance to a charge can develop.

Extended Cold Weather Storage:

Winterizing of the domestic water system is a necessity when storing your coach around or below freezing temperatures. If your coach is exposed to freezing weather and has not been properly prepared it may be damaged by possible ice expansion.

• Water lines, water heaters, hydronic heating systems, icemakers, water filters, pumps and faucets etc. are at potential risk. (See your Foretravel Owners Manual or other component specific manual for more details).

• If power is unavailable at the storage location for an extended period, in order to minimize battery drain, turn off master disconnect switch (located by entry door). This master disconnect switch will turn off everything on the coach battery, except the L.P. /CO detectors. If you have a 2 or 3 way refrigerator this must be turned off individually.

• The Engine batteries are not affected by the master disconnect. If no power is available they should be charged fully and the ground cable disconnected. If power is available the boost switch should be activated weekly to maintain them.

• The coach should be stored with the fuel tank full to reduce possible condensation in the tank. For prolonged storage (60+ days), use an additive with an algaecide.

• Take steps to address possible rodent or pest infestation.

• Remove all perishable food from cabinets and refrigerator.

• Clean roof top air conditioner filters and cover if possible.

• Pull Shades, close blinds and clean the interior.

• Prepare generator for storage. If possible try running generator with a load on it at least a ½ hour per month.

• To keep the coach highway ready run the main engine at least ½ hour each month. Driving the vehicle at highway speeds once a month for 10 to 20 miles will help keep the mechanicals in good working order and also helps protect tires from non use damage.

Engine Oil Vicosity

From time to time we get questions about engine oils and various aspects of how they are rated and what the designations mean. One of the least understood may be the numbers on the front of the container.

In the old days oils would have a single rating such as SAE 30. That rating was simple enough to understand as this was termed “30Weight”.This meant at operating temperatures a “30 Weight” would be thicker than a “20 Weight” and thinner than a “40 Weight”.

Then multi-grade oils came on the scene for good reason. These oils met SAE specifications for the low temperature requirements of lighter oil and the high temperature requirements of heavier oil. You may have also heard of them referred to as all-season and all-weather oils. All of the engines Foretravel currently use are factory filled with a multi-grade SAE 15W-40.

In simple terms, oil is rated for viscosity by heating it to a specified temperature, and then allowing it to flow out of a specifically sized hole. Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating.

The temperature requirement set by the Society of Automotive Engineers (SAE) is 0° F for the low temperature and 210° F for the high temperature. Oils meeting the low temperature rating have the “W” (winter rating) after the viscosity (example: 15W). Oils meeting the high temperature requirements have no letter (example: 40). So a 15W-40 would have a “winter rating” of 15 at 0° F and a 40 rating at 210° F.

The wider viscosity range of multi-grade oils allows for much wider temperature ranges than single weight oils. Most modern multi-grade oils are formulated from various oil grades and additives so the oil will have the best characteristics of both thick and thin viscosity oils. Better flow at low temperatures allows for easier starting and better cold start lubrication, yet retains enough thickness and film strength at the high temperature range.

For our diesel engines the SAE 15W-40 is a good all season multi-grade and is good for engine starting down to approximately 10° F and provides for best engine durability at higher ambient temperatures. It will work well for the typical areas of the country you will be heading off to in your Foretravel.