PREVOST, The Ultimate Class
Regular Care and Feeding
The common belief is that the Prevost chassis is a two-million mile shell. It is designed for the long haul. However, most Prevost motorhomes have far fewer miles than that. After you have seen enough Prevost coaches, you will find that most have about 10,000 miles per year on them, as an average. A good rule of thumb to determine the use of a coach.
This presents some challenges to the Prevost owner.
Since the coach is being used way below its intended mileage, there are a number of maintenance items which should be regularly inspected or tested, especially once a coach is a couple of years old to insure safe, reliable service from the Prevost.
In commercial or tour bus use, a set of Michelin Pilote tires can run over 100,000 miles, barring a road hazard. The Michelin tire is the optimum tire for the Prevost; they are stock. However, when a Prevost is not used on a regular basis, the difficulty emerges when ‘dry rot’ begins to appear on tires. "Dry rot" is a combination of minimal use of the tire and UV rays from the sun. Look very carefully at the sidewall of your tires. "Dry rot" looks like fine, webbed lines, not very deep which appear on the inside circumference of tires. This means that the sidewall has begun to deteriorate, and it is not possible to determine the extent of damage to the tire from a visual inspection. While there may still be casting marks and a great deal of tread on the tire, "dry rot" can mean replacement.
Tire replacement is done according to the proper schedule: Put your best tires on the front, the next best tires on the drive axle and the least reliable tires on the tag. Tires with erratic wear or extensive ‘dry rot’ need to be inspected by a qualified Prevost or Michelin person. There are some tires which can ‘run out’ and regain their original form upon rotation; others simply need to be replaced.
One Prevost owner carries a baseball bat with him. He routinely whacks each tire along his journeys to make sure that tires are up to proper inflation. His idea is that without having to check the individual pressure of each tire, he can determine from the sound of the ‘whack’ if a tire has become low. His reasoning, which sounds good to this writer, is that at 70 miles per hour, a 250-pound blow out can do a lot of damage to a Prevost. No one wants a blow out. A front blow out is a very bad day in anyone’s book, especially with a 20-plus ton coach at 70 miles per hour.
All that is between you and the road are the tires. Got it?
Lack of regular use of a Prevost can also allow seals to dy out and begin to leak. A quick way to check for seal leakage is to keep your rims very clean and look for spidery oil which may be coming from the center of the tire rim. Depending on what type of cover is used on a particular bus, the oil can take more or less time to emerge and be visible. Replacement of seals for outer tires is a relatively minor maintenance item at a qualified facility. A leaking inner drive axle seal is more complicated. A leaking seal on one side may likely indicate that there is or will be one on the same axles on the other side.
Oil and Coolant
Either low oil or coolant will keep your bus from starting. Complete oil changes should be done at least once a year. In addition, coolant should be checked for SCAs (Supplemental Coolant Additives). Coolant without SCAs can cause cavitation and cavitation can cause engine failure. Make sure both reservoirs are filled and check the engine oil level. It is common for 8V92's to use as much as a quart of engine oil per 1,000 miles and more with heavy use. It is not common to be using much coolant. If an engine is eating coolant, this should be checked out right away. Either it is infiltrating into the cylinders (very bad) or leaking. If you have over-the-road air conditioning, you will find that your bus will require about 20-percent more coolant than a non-OTR bus; it circulates through the OTR system. That means the bus must be run up to temperature, which take as much as 45 minutes at idle or more for the thermostat to kick in. If you are in a warm climate, it is possible that a flushed coolant system may appear to be full; just wait until you turn on the OTR heaters and find that the bus won’t start if the thermostat has not run up to temperature before topping off the coolant.
If it is cool outside, this is a good time to look at the rubber-clamped connections for small coolant leaks. Believe it or not, there is a ‘cold weather’ leak potential, as the metal coolant pipes contract more than the clamps holding the rubber hoses. The fix is easy: Tighten the clamps while the engine is still cold.
Make sure to use the proper oil for your engine. There are a ton of Detroit Diesel dealers and shops around the country and usually can supply you with the proper grade and weight of oil for topping off your reservoir.
Look carefully at each battery, engine batteries, chassis batteries and the generator battery. If you can see any crud growing on the terminals, pull the terminals and clean them; cover them with grease after they are cleaned to slow down further growth. Make sure the terminal connections are solidly affixed to the cables, replace them if not. This is also the time to check the condition of each battery. The rule of thumb here is that if one battery is bad, the entire set must be replaced. Even one cell in one battery means that the entire bank of batteries needs to be replaced. Put the best batteries in your Prevost that you can find. If you discover that relatively new batteries are going bad, rethink the charging that is happening with your coach. If there is a manual battery charge, only use it when you have to: Constant charging of batteries when it is not necessary will eat batteries very quickly.
Take a hard look at the shore line cable. Is it being pulled out of the 50-amp connector? We all use shore line cables longer than we should because, "just one more time" seems to be the rule. This can be very dangerous: Pre-1992 buses do not usually have a fully wired grounding system in them: Your only ground is the screws in the electrical connection receptacle. Make sure they are tight on all buses.
Run the generator. Most Prevost conversions have great generators. And most generators are not used very often. Let ‘em run and put a good load on them; air conditioners, microwave, all the goodies. Most generators have air bags under them, check to make sure they are properly inflated and in good condition. A generator compartment should be in impeccable condition. If you begin to spot oil or any other contamination, find out why. Check coolant levels and oil here too. This is your ‘little diesel’ requiring the same care and attendance as the big one in the back.
The air bags under the Prevost bus are robust, top quality air bags. But like anything made from rubber, with minimal use, they are subject to cracking and ‘dry rot’ just like tires. Leaking air bags are a pain, potentially dangerous and should be kept on good condition. Unless it is cold outside, they should maintain pressure at least overnight. When an air bag is replaced, it, like seals, may likely require replacement on the same wheel on the other side. Have air bags replaced only at Prevost-qualified facilities.
There are many places where the auxiliary air system operates a wide variety of mechanisms on the Prevost; from wipers, to fan pistons for cooling, to toilets to passenger foot slides. Chasing auxiliary air leaks can be an endless and very expensive enterprise. Keep on top of auxiliary air leaks before they are numerous and you have more than one or two to discover and fix.
The Prevost air system is one of the more complex systems in the bus. There are two valves in the rear, one in the front; air dryer, suspension, brakes and auxiliary air. The proper operation of the air system is essential to the safety and comfort of this wonderful machine. Make sure it is always in top-notch condition.
Most Prevost motorhomes are kept in excellent exterior condition. They are prized possessions. However, in time, some of us get used to the subtle fading of clear coat over the paint. It doesn’t hurt to regularly wax, with top-quality high Carnuba wax, the paint. On older coaches, look for yellow bubbling: This may portend a penetration of the clear coat. What happens, especially in warmer climates, is that the clear coat has been compromised. The fix here is to have the clear coat sanded and refinished. Insure the job is done by a competent shop. Many older Prevost buses have terrific paint jobs done on them originally and no one would want to have a ‘fix’ degrade the overall quality of the original paint job.
Wooden surfaces, such as doors, cabinet ends and trim can use a regular cleaning with Murphy’s Oil Soap or other such products. Avoid Pledge or other such products, as they leave a sticky (but nice smelling) gooey finish on wood. Many Prevost owners who use their buses regularly are living in relatively small spaces and it is so easy to avoid a complete cleaning. Look carefully at commonly used areas, around cabinet pulls and such for slight wear. For synthetic cabinetry, look carefully for delamination of the surfaces. This is rare, but can be repaired before it spreads.
Corian is a blessing and a curse. If, after many miles, there are no cracks, you are in great shape. However, if you see a small hairline crack, the best fix is to drill a very small hole at the end of the penetrating crack to relieve the pressure. In most cases, this can be filled by products available at a high-end kitchen cabinet shop and the fix is done. Replacement of a large area of Corian is expensive, especially if the counter top has a molded sink. Very fine sandpaper can dress up areas of wear or discoloration.
Floor tile surfaces which have initial cracks, especially with larger tiles indicate that the bus has flexed, perfectly normal. The cracks in tiles are generally not repairable by the owner, however, grouting can be purchased at a home supply store for refilling chipped or missing grout. There are now latex grout products which are easy to use and may closely match original grout.
Commercial carpet cleaning can be used to freshen up carpet. Make sure the firm uses low-water sudsing products, as a saturated carpet will take forever to dry and may damage the underlayment of the floor surface.
Regularly check under cabinets around sinks and water accessories, including ice makers for any drips, staining or evidence of leaks. Over time, even the best fittings will work loose from vibration and flexing. Tighten where necessary. Cabinets should be well-ventilated to insure that odors from cleaning products are not embedded in carpeted cabinetry. Don’t forget to check around drain seals from sinks and faucet areas.
Whenever you have a chance to do so, air out your bus. Keep windows open which can be opened. If you have a fresh air exhaust fan, run it while windows are open. Fresh air circulation in the small space of a bus keeps the inside pleasant. If you have a chance to do so, open cabinet doors on a sunny, dry day and air out the entire bus.
The inside of a Prevost motorhome compartment should be impeccably clean and in good condition. Buildup of a little oil or grease leads to the accumulation of dirt. This combination then turns into grit and the ensuing grit can turn into a very big job down the line. There are now a number of auto products which can be used to routinely clean the engine compartment without damage to electrical components or paint.
While you are there, check for the condition of belts, electrical connections and any leaks you may observe. Remember that the rubber fittings connecting electrical systems, coolant, sensors and the like are subjected to the outside elements and tremendous heat. Keep them pliable and clean. Many auto products can be used to accomplish this task. Keep a spare set of belts with you while you are on the road. Better to have them and not use them than to need them and not have them!
Regular replacement of the air filter is a must. Diesel engines do not like contaminated air intake. Detroit Diesel filters are commonly available at most NAPA or other auto parts stores and are not very expensive. With a rachet wrench, most owners can replace them in less than a half hour. As a matter of course, they should be replaced every six months or less, depending upon use. A single exposure to one of those "guys grinding cement on the interstate" can clog a filter. It is easier to replace a filter than clean it.
Check out the exhaust system. Many owners use high temperature paints to coat the exhaust and avoid the inevitable rust. After some period of time, rust will eat through the exhaust system and eventually create a hole, requiring replacement of the system.
It is very easy to avoid the necessary chores in keeping a Prevost motorhome in top condition. We are all busy with our lives and can put off regular maintenance and fussing with our motorhomes.
The above items are not a complete maintenance list and certainly not all-inclusive by any means, but represent some ideas and things to look for. Nothing is better than a routine inspection and maintenance schedule by a competent Prevost conversion shop; highly recommended. But there are many routine tasks which nearly any owner can accomplish a little at a time to keep that 2-million mile bus looking and working like new.
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