Good Sam RV Travel Guide & Campground Directory

Mark...My Words

Hi, Mark:

When we use our motorhome, the black-water tank leaks as we travel. As we go to uncap the waste water connection, there is always fluid that has leaked into the pipe. This makes a nasty mess as we hook up to the camp sewer. We have had two different RV dealers look at the problem. Their only solution has been to install a new black-water waste valve. They both filled the black-water tank and let it sit several hours to check for leakage after the new valve was installed. Both times there was no leak into the pipe. But as soon as we take our next road trip and go to hook up the sewer, there is fluid that has leaked into the pipe. We are sure it is the black water since there is blue coloring from the additive to the black tank. One of the dealers tried several times and just gave up after we took it back several times. The last time we had a new valve put on, we only drove 10 miles to our campsite and voila! There was water in the pipe!! Do you have a solution to this mystery??
Thanks, Mark

Hi, Mark,

That is a tough one indeed. If the valve has been replaced more than once and you are still having a leaking issue, it is hard to blame the valve. I do have some thoughts and suggestions, however. First, are you dumping the tank properly? You should only dump the black tank when it is at least one-third full. In fact, the fuller the better! When the tank is full, the rapid surge of fluid leaving the tank carries the wastepaper and solids along. This helps prevent any of those solids or paper products getting hung up in the valve seal, causing leaks. If you must dump a partly full tank, close the valve after dumping and add water to the tank with either a built-in tank flusher or a garden hose until it is at least half full, then dump it again. This may help a lot with your leaky valve problem. Also, are you using a toilet paper that completely breaks down in the tank? All toilet tissues are not the same. You might try using an RV toilet paper for a while and see if it helps. If the tissue isn’t dissolving, it is very easy for a chunk to get wedged into the valve seal, and that will also cause a leak. Finally, if nothing helps, you can try fitting a second dump valve onto your sewer outlet. This additional valve will allow you to hook up your hose without problems, even if your black-tank valve is leaking. Here’s an example of what I’m talking about: This valve simply twists onto your dump fitting on the rig, and you can cap it and leave it in place while traveling. It is a band-aid solution, I admit, but it will make hooking up your sewer hose a lot less disgusting when your main black-tank valve leaks.

Hi, Mark,

I know you receive many questions regarding fuel economy in this high-cost fuel period we seem to be endlessly stuck in. We travel in a 38' 2005 Coachmen Cross Country, 300HP turbo-charged Cummins. What can we do to ensure optimum fuel mileage? I mean besides keeping it parked in our driveway.
Thanks, Jon

Hi, Jon:

I wish I had a magic bullet for you, but I don’t. However, good common sense and attention to preventative maintenance and operation will help you get the best possible mileage out of any vehicle. Here’s a list of some of the things that affect mileage.

• Tire pressure. Check tires regularly and keep them properly inflated.
• Wheel alignment. Out-of-alignment conditions can really hurt overall economy and ruin your tires to boot.
• Air filters and fuel filters. Change regularly! See your owner’s manual.
• Use synthetic oils. Synthetic oils can improve gas mileage by lowering friction.
• Brakes. Have brakes checked regularly. A dragging brake can really hurt mpg.
• Engine tune-up. Keeping the engine in top running condition helps a lot! Fix minor problems before they “go critical.”
• Driving habits. I know, nobody wants to hear this, but the way you drive has a big effect on economy. Slow down! Especially in high-profile RVs, just driving slower (within reason) will reduce fuel consumption. Gentle starts and gentle stops will stretch your fuel as well.


I have an Onan generator in a 2010 Melbourne. Have tried to remove the spark arrestors. Just cannot get them out. The end is square. Also, they seem to be made of brass. Is there a special tool needed? Or just brute force? The manual says that they need to come out every 50 or so hours and run the generator for about 5 to10 minutes to clean out the muffler. It goes on to say that the generator performance will decrease it this is not done. How much is performance degraded? Thank you for taking the time to review and answer my questions.

Hi, Leo,

The proper method for removing and/or cleaning the spark arrestors depends on the model of the generator. Perhaps the easiest way to get the procedure is to visit and enter your model number (found on the ratings plate on the generator). Download or view the manual and find the procedure for spark arrestor maintenance. On some units, you simply remove one or more plugs from the bottom of the muffler and run the engine for a few minutes. On others, you have to remove a screen from the muffler outlet. If the arrestor is not cleaned, it will progressively clog over time and result in a significant loss of power (it will restrict the exhaust gas flow through the muffler). Normal hand tools should do the trick; special tools should not be needed. If you are having problems removing the arrestor plug or screen, you can apply a small amount of penetrating oil to it and tap it with a hammer (gently) to help the oil penetrate. Sometimes these things get really tight, so it may require a bit of force to remove. If you can’t get it out, you will eventually have to take it to a service facility and get it done.

Hi, Mark,

I was hoping for the know-how on how to hardwire an inverter into my 2005 Jayco Greyhawk (you have seen it and weighed it). I turn on the generator for the coffee and charge computer, phones and camera batteries while boon docking, and that is the only thing it is needed for. Enjoy your writings,

Hi, Chuck,

Most inverters large enough to run your coffeepot will have to be permanently installed in your RV (hardwired). Inverters of this category that are designed for RV use are fairly easy to install if you have some electrician skills. However, if you really don’t know much about electricity and basic wiring, it is a job best left to someone who does. That being said, the number one resource for installing the inverter will be the installation manual that came with the device. If you have an inverter already in mind, get a copy of the installation manual before you buy it and read up on the installation procedures and wiring requirements. There are also some good online resources that will help you either to safely complete the installation or to decide that it is beyond your comfort level. This is a great text article that covers the basics of what needs to be done (and figured out). This article shows some alternative installations for different-size inverters. This article is a step-by-step description of a typical inverter installation.

The job of hardwiring a large capacity inverter is fairly complex. If you can live with running the generator to make the morning coffee, all of the other tasks you mentioned can be handled by small portable inverters that do not require time-consuming installation. Plus, they are a lot less expensive!
Dear Mark,

Do after-market holding-tank flush kits really work, or are they a waste of money? I am looking for an easier way to flush out my black-water holding tank and, if they work, maybe adding it to my two gray tanks. I have seen some that you drill a hole into the rear of the holding tank to attach them and then run a line to one side of the trailer where you hook up a hose. If they do work, could you recommend a specific type or brand? Thank you,

Hi, Tom,

I can give you my personal recommendation: I find that these tank flushers are a mighty fine addition to your RV. They really do work and help make tank flushing a painless task. Sure beats dragging a garden hose through the door or bathroom window to use an old-fashioned flushing wand! I have installed them on all of my RVs for both the grey and the black tanks. I prefer the kind that has an extension hose that lets you locate the hose connection for the flusher in a convenient place. I have used the Camco brand in the past, and they are reliable. A couple of tips: 1) Install the flusher head at the far end of the tank, pointed towards the dump valve connection if possible. I think they work better that way. 2) Always be sure that the dump valve is open on the tank you are flushing. If, for some reason, you feel you must close the dump valve while you flush, never, never walk away or get distracted by something else. You will be setting yourself up for a major disaster when the tank overflows (and it will!).

Hi, Mark:

I've always enjoyed your column, so decided this was worth a try. We have a 2004 TropiCal. The generator has always been very trustworthy. We haven't used our RV for about two years. To make a long story short, the generator fires up and hums along perfectly for two minutes, then shuts down. I read the manual and know that it is showing a code 33, which is high coolant temperature. We have checked the oil, coolant level, air intake and filter and exhaust. Everything seems to be fine. The fuel filters were changed recently by us, and we have three-quarters of a tank of diesel, so I know that isn't the problem. Everything that I have read online points to a faulty high coolant temperature sensor. Our generator is in the nose and is not on a slide-out, so it will be a difficult fix. My question to you is: How much should we expect to pay to get this fixed at a CumminsOnan dealer? We would love to be able to do this ourselves, but I just don't know if it is worth the trouble to pull the generator. Please give me your best advice.
Thanks, Peggy

Hi, Peggy:

Let’s see, that generator is about eight years old, and it sat unused for two years. It may be time to bite the bullet and have it inspected and serviced by CumminsOnan. Although the coolant sensor may be at fault, it might be something more critical, like a clogged cooling passage, or bad water pump, that’s causing the generator to shut down. That unit also needs an oil change and a coolant flush/refill before it is put back into operation if it sat idle for two years. Given the age and history of the unit and the difficulty accessing it, this might be one for the service techs. It will probably be somewhat pricey, though. Most shops charge at least $100 an hour for labor and will nick you pretty hard on parts, too. You should be able to take the RV to a local CumminsOnan dealer and ask them for an estimate before any work is done. They should have a standard procedure book that gives labor hours for various maintenance tasks, and they can give you some idea of the price. I would be surprised if you got away for less than $500, though, as I’ve heard that the Onan standard 500-hour maintenance service for that generator can run you upwards of $500. Please let me know what you decide, and how much it winds up costing you, so I can pass it along!


Hi, Mark:

How do you check a converter/charger to see if it is working properly? I don't believe that mine is trickle-charging my battery.

Hi, George:

Here’s a simple test that’s really easy, and all you need is a digital voltmeter. Leave the RV plugged into shore power overnight, and then check the voltage directly at the terminals of the house battery(s) with your meter. If you are reading 13.2 to 13.8 volts, then your converter is probably fine. If it is below 13v, chances are your converter is broken, is not getting AC power, or the connection between the battery bank and the converter is open. If the answer is “none of the above” or your voltages are way out of range, get an RV tech to look at the system.


Hi, Mark:

I understand there are two companion books that truckers and many RVers use to research grades, clearances, etc. when driving their rigs in the mountains. We are planning a trip from Illinois to Los Angeles, CA, and would like to get a better understanding of the interstate options. Can you provide us with the name(s) and a source to purchase such references?
Thanks, Bill

Hi, Bill:
The two books you are looking for are titled Mountain Directory West (and East) for Truckers, RV, and Motorhome Drivers, produced by R&R Publishing. Selling for around $16 each, they are a super resource for any RV owner. The “West” book covers Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The “East” book covers everything east of the Mississippi. You can buy them at most large truck stops, or directly from the R&R Publishing website at They also offer the directories as Windows-only e-books for about the same price.


Mark NemethMark Nemeth has been involved with all things RV for more than ten years, including almost 5 years on the road as a fulltimer. Nowadays, Mark is parked for a while and works on staff for the Escapees RV club as technical advisor, consumer affairs director, and instructor in the Escapees RVer's Boot Camp program.

Founded in 1978, the Escapees RV Club provides a total support network for Rvers that includes a wide variety of opportunities for fun, adventure, and education. CHAPTERS There are 51 chapters across the U.S., Canada, and Mexico that offer local luncheons and rallies within 150 miles of home. Everyone is welcome to attend. HOPs Theme–related outings and adventures held across the country. ESCAPADES Five–day events, Escapades offer over 60 seminars and workshops to educate, entertain, and enhance the fun and use of RVs. PARKS Our RV park system offers short–term, long–term, and home–base parking options. MAIL SERVICE The best mail–forwarding service in the country. Members can personalize their mail delivery receiving only the mail they want when they want. PLUS MUCH MORE! A complete listing of all Escapees events, and a comprehensive list of member benefits are found at

Escapees RV ClubSome content previously printed in Escapees magazine, published by the Escapees RV Club. All material provided by Mark Nemeth, Escapees Magazine Technical Advisor and Boot Camp Instructor. For more information about the Escapees RV Club, please visit or call 888–757–2582.

Woodalls subscribers can save $10 on a new Escapees membership! For more information, visit the Escapees website.

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