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RV Doctor ColumnRV Doctor #270 Dear RV Doctor, my Atwood/Wedgewood oven is having pilot light problems. Specifically, it will not light any longer with the thermostat set to "pilot on" position. I have to turn up the dial to about the 120 degree setting for the pilot to sustain a flame. From there, I can turn the thermostat up and the oven will ignite and burn until the set temperature is reached. At this point, the main burner shuts off, the pilot stays lit but the oven does not reignite when a temperature drop would normally cause the feedback system to relight it. Thermostat shot maybe? Glenn Gibbons, (El Portal, CA) Glenn, your diagnosis may be on the money, but there could actually be two independent causes for your symptoms. When the thermostat is turned to "pilot on," a very small amount of LP is passed through the thermostat down to the oven pilot. In your case there could be a partial blockage in the standing pilot orifice preventing it from initially lighting. It will be necessary to remove and disassemble the pilot assembly and soak the orifice in acetone or a like substance. Be sure to wear protective goggles and gloves when handling acetone. Blow the orifice with compressed air in the opposite direction to the flow of LP and reassemble the pieces taking care to position all components correctly. This should take care of the problem of lighting the pilot that first time. Once lit, this standing pilot stays lit until there is a call for heat by turning the thermostat to a set point above 100 degrees. Any time the thermostat is turned up, an additional flow of LP enlarges the pilot enabling it to envelope another thermal probe attached to a separate safety valve. Once this extended pilot heats the probe sufficiently, the safety valve opens and LP flows to the main burner and is ignited. After the temperature has been satisfied, the safety valve closes and the pilot flame remains until the next heating cycle. Attached to the thermostat is another probe, the temperature sensing probe, positioned inside the cooking area of the oven. This is the portion of the thermostat that monitors the inside temperature and allows the thermostat to ignite the secondary pilot again when additional heat is called for. Many times a thermostat is wrongly accused of being faulty when, in fact, the temperature sensing probe may simply be covered with cooking oils or grease, or even oven cleaner, and is simply not sensing the temperature correctly. Before condemning the thermostat, thoroughly clean the temperature sensing probe located at the rear of the oven. It may be suspended in place at the very back inside the oven. Be sure it has not fallen or become damage. You'll notice it is attached to the thermostat by a very small diameter capillary tube. If this tube becomes kinked or broken, the thermostat will have to be replaced. Do these first; clean the orifice as described above and the temperature sensing probe and see if the performance is improved. Now if the pilot flame ignites and stays lit when the thermostat is placed to "pilot on," but does not become visibly larger and envelope the sensing bulb when the thermostat is set to a temperature above 100, then you can be sure the thermostat is faulty. Dear RV Doc, my Shurflo water pump in our Holiday Rambler will not build pressure. The pump makes its noise, and water is in the line feeding the pump, but it simply runs and runs, never reaching enough pressure to cut off. There is an accumulator tank in the system. No water is dripping out from under the motorhome. Some slight water pressure comes out of the sinks. R. Lott, (Pensacola, FL) R., there are a couple of possibilities here....first, check the piping or hose located between the tank and the pump. Your symptom could be caused by an air leak on the inlet side of the pump. The pump could be sucking air while trying its best to pump the water. I have seen in the past a split in the tubing in this section with the same result. It will probably not leak water since there is no pressure other than atmospheric on that side of the pump and the pump is evidently pushing some water through the system. Be sure to tighten all hose clamps or fittings. If there is a filter/strainer located in this section (there should be one there to protect the pump), replace it or check it for air tightness. Of course there is the possibility the pump itself is faulty. Not knowing how old it is, I can only surmise at this point. It might be prudent, however, to have the pump bench tested if my air leak diagnosis is flawed. Dear Gary, the tires of my 5th wheels are ten years old, but look good. They are steel belted. Do I have to change them just because of their age? And if so, are pickup truck tires good for my 5th wheel? The GVWR of my 5th wheel is 4800 pounds. Robert Despaux, (Beauport, PQ) Robert, don't be fooled by tires that "look good," or have very low miles on them. The major concern with tires on RVs is age and the amount of exposure to ozone and ultraviolet rays they have sustained. Rarely do RV tires "wear out." According to Michelin's own handbook, "The life of a tire used on an RV cannot be measured by miles alone." In most cases, RV tires will probably last from five to seven, maybe eight years before needing replacement, regardless of the amount of miles on them. Of course, this depends a lot on your driving habits too. A thorough examination, inside and out, can determine when questionable tires should be replaced. Over the years your tires have been exposed to countless hours of UV bombardment as well as ozone poisoning. The fact that the tires may appear to be in good shape is misleading. Many of the ills associated with ozone/UV exposure and lack of physical exercise and/or improper use will result in damage to the inside of the tire and within the sidewalls of the tire. The exterior may look just fine though typically, small, hairline cracks may be found on the sidewalls. Do not compromise the safety factor; get a new set of sneakers soon! Some truck tires may suffice, but to be sure, check with your local tire dealer.
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