Tech Q&A: November 2020

five-gallon propane tank

LP-Gas Leak-Down

Red letter Q Is there a general rule as to how long the LP-gas lines should hold pressure after the cylinder has been turned off? I turned mine off, and the next day the red empty indicator came up in the regulator. Is a day all right or should I be looking for a leak?
James Pittman | Fenton, Michigan

Green letter A Technically, any LP-gas leak is a bad leak, Larry, so yes, you should be looking for the leak. The usual soapy-water solution brushed, sprayed, dribbled or poured on the joints is a good way to track down where that  LP-gas is going. It may not seem like much but consider if you’re dry camped and the LP-gas is turned on for several days. That overnight leak-down volume will still be happening while you’re using the system, day and night, and that equivalent amount of leaked  LP-gas can add up in a hurry. It’s also, of course, a fire hazard. If you can’t find the leak, take the RV to a dealer with a trained  LP-gas professional to diagnose and repair the system for you.

A spot to check that some people miss is the regulator body. The diaphragm inside it can fail and allow the gas to escape via the vent opening built into the regulator. With the LP-gas turned on, you may be able to catch a tiny scent of LP-gas near the vent opening on the back or lower side of the regulator. If so, it should be replaced. You didn’t say how old your RV is, but these regulators do fail, and they aren’t that expensive to replace. It’s a good step to take.

Freshwater-Tank Cleaning

Red letter Q I am not sure if this is the correct place to ask this question but I was wondering if you have any suggestions for a safe product to clean our potable water holding tank, besides bleach. I do not like to use bleach as I don’t feel like I can get it all out of our water tank and I do not want to use the water when it still smells like bleach.
Martha Tozer | Curwensville, Pennsylvania

Green letter A You came to the right place, Martha. If you can’t get rid of the bleach smell in your water you may have used too much bleach in the mix. As a rule, 1⁄4 cup per 15 gallons of freshwater-tank capacity is enough to do the job. Did you try the baking soda cleanse afterward? Once the bleach water is drained and rinsed, add about 1⁄2 cup of baking soda per 15 gallons of freshwater to the tank, fill it, run it through all the faucets and such, then drain and refill as before. The baking soda usually does the trick.

For a commercially available solution, Thetford offers its Fresh Water Tank Sanitizer product and we’ve heard some good things about it. Also, Camco has its Spring Fresh and TastePure. Those are good alternatives to the bleach-sanitizing process.

Slideout Awning Prep

Red letter Q Referring to the “Hands On” article on installing a Solera Slide Topper in the May issue, slide toppers are a great idea. I suggest that step zero should be to examine and clean the slide roof and check and lubricate the top seal. It will never be that easy to do once the topper is installed. I would appreciate any suggestions on how to do these things. Our camper has three slides and we have toppers for all three.
Ed Austin | Newport News, Virginia

Green letter A That’s a pretty snug space to get into for maintenance, Ed, and we agree, treating the seal and cleaning the roof before the awning goes on are a good idea. Even after installation you’ll want to re-treat the seals every now and then. About all you can do at this point, short of removing the awning, is to use a long-handled device to apply the slideout seal treatment and to do a slideout roof cleaning.

You might try a small block of wood attached to the end of a PVC pipe, wrapped with fabric like an old terrycloth towel, for starters. Shape the wood to fit against the rubber seal area, saturate the fabric with the seal lubricant of your choice and reach in to spread the lubricant on the seal. For cleaning the roof, a long-handled RV wash brush of some type is probably the best tool for the job.

PEX Pipe Leak

Red letter Q There was a leak that was coming down into the basement compartment of our new Jayco HT 24.5 fifth-wheel. The bathroom sink was just above that and the PEX waterline was installed at an angle up from the space below. In the back of the vanity cabinet, the angle of the semi-flexible PEX caused the rubber washer in the female-threaded supply fitting to be improperly seated on the faucet (a shortest distance between two points issue). I had to get a new washer (70 cents) and then purchased two 90-degree PEX fittings, a length of PEX, a PEX clamp crimper, PEX clamps and then rerouted the supply to come straight up to the fitting. Problem solved and a new tool for my trailer tool chest.
Rolf Tandberg | Missoula, Montana

Green letter A It’s always a good idea to have PEX-pipe repair tools in an RV’s kit, Rolf, and we’re glad you were able to solve the problem yourself. The situation you described, with the pipe stretched and bent excessively between point A and B, is a common lazy installation detail we see all the time in RVs. Rather than manufacturers using 90-degree elbows or other appropriate fittings, the fastest and cheapest solutions find their way down the assembly line.

It’s good that owners are able to upgrade to a proper setup as you did and eliminate that leak source before it becomes a problem later with saturated or rotten floor woodwork. As an alternative to carrying PEX tools and fittings, consider putting a selection of push-to-connect fittings for ½-inch PEX in your RV toolbox. SharkBite and Watts AquaLock/SeaTech are two brands of those, for example.

Truck and Clearance Heights

Red letter Q In the response to the Moore’s question in August’s “New Truck Sits High” letter, you mention that if the overall height of the unit is “Any higher than 13 feet, 6 inches” that you could be in trouble. Why that specific number? I understand about bridge/tunnel heights; however, most are above that number and are posted on the entrances.
Alan Grossman | via email

Green letter A The Department of Transportation (DOT) has established a minimum of 16 feet of clearance for bridge overpasses and the like on interstate highways, with variances on secondary roads. For example, California limits vehicle height to 14 feet statewide. In Massachusetts, “No vehicle shall exceed a height of thirteen feet six inches” without a permit. So, that 13-foot, 6-inch figure we used allows for some extra safety space above the vehicle height in most spots. A lot of drivers don’t pay close attention to vertical clearances, so the restricted vehicle height is a good idea.

Technically, within the realm of handling and stability and good judgment, you can tow something taller than 13 feet, 6 inches if you want to, but you’ll be taking a lot of risks on the highway.


Man leaning over engine wearing blue shirtJeff Johnston served as technical director of Trailer Life for 20 years and has been an RV enthusiast, mechanic and writer since he could hold a wrench. In his monthly RV Clinic column, Jeff replies to Trailer Life readers’ technical questions about RVs and tow vehicles. He also serves as associate producer of Rollin’ On TV, a nationally syndicated television program for RV enthusiasts.

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