Found and fixed a slow propane leak: lessons learned . . .

[profdant139]

This is a much longer story than the usual "repair report," but I hope that it will help some future leak sufferer avoid some of the mistakes I made. And before I get going, a big "THANKS!!" to all of the forum members who gave me so many useful pointers along the way. (You know who you are, and you may recognize some of your own tips and tricks described below.)

So -- on a recent camping trip, DW said that she smelled propane once in a while -- very faint, intermittent, impossible to locate, but she was sure there was a leak somewhere. I couldn't smell anything. (But I have since read that women often have a better sense of smell than men do.)

When we got home, I did an experiment to see if we really had a leak: I weighed the propane tank on the bathroom scale, hooked it up to the trailer, and turned it on. The next day, the weight of the tank had dropped a pound, equivalent to a quarter of a gallon, or roughly an ounce per hour. Yep: a very slow leak somewhere.

Next, I "painted" all of the propane lines and connections with a soapy water solution. Did not see any bubbles.

I removed the plastic housing that covers the bottom of the regulator and painted the whole thing with soapy water, including the seams and the vent. No bubbles.

Next, I bought a General propane detector for $35 at Lowe's and crawled around under the trailer, letting it sniff all of the lines and connectors. (Note: this was on a breezy day -- more on this later!) The detector did not go off. Just to make sure the detector was working, I briefly turned on one stove burner without lighting it. The detector went nuts right away.

Next, I bought a container of Oatey Mega Bubbles for about $8 at a plumbing supply store. I painted what I thought was the whole propane system. (Note: more on this later!) Still no bubbles.

Next, feeling desperate, I replaced the regulator with a new one from Camping World (around $50). I did the whole tank weighing trick. We were still losing propane. Darn! I thought the new regulator would do the trick.

I was getting ready to take the trailer to a dealership and let them find the leak, at great expense. But one calm, windless morning, I opened the propane valve, to give it one more try. (By the way, did you know that the propane valve should be opened slowly? I didn't, but it turns out that if you open it fast, you can damage the regulator.)

Standing near the lower fridge vent, I caught a faint whiff of propane. I removed the fridge vent, grabbed my General gas detector wand, and: Nothing.

But I recalled that the outside barbecue quick-connect fixture was under the trailer right near the lower fridge vent. So, what the heck -- let's give it a try.

Very slowly, I slid the wand along the barbecue outlet. The little green light, indicating no propane, flashed and beeped every few seconds.

And then: a yellow light! Just for a moment. I narrowed down the search area. Yes! The infamous pinhole leak. The yellow light indicates a low-level leak. A bigger leak would have triggered a red light.

I confirmed it with some Mega Bubble -- I had to force the little applicator into a narrow gap between the frame of the trailer and the top of the barbecue connector. (More on that later.) Bubbles slowly emerged. The bubbles were unambiguously inflating from within -- these were not the small random bubbles you'd get from a sudsy brush.

The rest was easy. I got a black iron (not galvanized) cap from the hardware store. I sprayed the barbecue connector with PB Blaster to loosen up the rust and waited a day to let the lube penetrate.

Using a pipe wrench to hold back on the pipe, I used a big crescent wrench to loosen the barbecue connector. (Usually, I avoid crescent wrenches but did not have a one inch open end wrench.) . I used yellow Teflon tape to seal the threads -- could also have used Teflon paste.

I then hooked up the tank, turned on the valve, waited a day, and weighed the tank. No leak!

Some important lessons learned:

When your spouse says she smells propane but you aren't sure if there is a leak, turn on the propane valve and weigh the tank on a digital scale for several days in a row.

Clean off the propane lines before starting the hunt for the leak. Mine were covered in dirt; I think that was one reason my initial testing was unproductive.

Before you buy a gas detector, first try the "soapy bubbles" test with ordinary dish soap. You may get lucky and save yourself a lot of money. They say a mix of five to one is best -- I later found that for a slow leak, you need a thicker solution.

When you buy a gas detector, first make sure it works by testing it over an unlit burner on the stove. The first one we bought did not work!

When you use the gas detector, I would wait for a really calm day. A breeze will disperse the propane from a slow leak. I think that is why my first inspection with the wand was unproductive.

Move the gas detector very slowly along the propane lines. It takes a few seconds for it to "sniff" each site. I think I was going too fast during my first inspection of the lines.

Even the inexpensive General gas detectors do work, when given a fighting chance. This was a really tiny leak, but the gas wand was able to pinpoint the pinhole.

If you use the Mega Bubbles, be sure to force the little applicator into every possible crevice. The applicator is about an inch wide. On my first try with the Mega stuff, I did not jam it into the space above the barbecue connector and thus missed the site of the leak!

When you apply the bubble solution (either of dish soap or Mega), be patient. If this is a really slow leak, the bubbles will not come shooting up at you. They will slowly inflate. The advantage of the Mega stuff is that the bubbles are fairly durable -- they do not pop quickly but instead will continue to inflate, making them easier to see than the bubbles from a dish soap solution.

Finally, be dogged and relentless. The chances are good that you will find the leak yourself, after spending many fun hours crawling around under the RV. I would guess that this particular project took me a total of 30 hours of work, most of it fruitless.

[profdant139]

Spent a frustrating hour trying to replicate the problem -- no luck. I could not develop a tight enough seal for my compressor nozzle.

I am guessing that if I had just tightened the bbq connector while it was still hooked up to the trailer's propane system, I would have discovered the leak was at the joint between the black iron stub and the brass connector. But instead of tightening an already-troublesome and utterly-useless (to me) bbq fitting, I chose to get rid of it and cap off the line.

But even though we don't know the precise origin of this particular leak, at least we've collected some tips and tricks that might save other folks from making the time-consuming errors I made during this search process.

[profdant139]

I don't know, at least not yet. I could not get eyes on the problem while the system was pressurized. There was no clearance for inspection. So I just removed the whole fitting and capped the stub. And when I removed the fixture, there was teflon paste residue on the threads.

But I hung onto the fitting. I am now trying to figure out a way to pressurize it with my compressor, so that I can see exactly where the air is escaping. I do not see any visible damage.

The weirdest part of this is that I am sure there was no leak during our last big trip, in November. So what could have caused a leak to develop? The bbq fixture was not subject to any stress -- we never used it, and it was tucked up under a frame member.

Wild guess: this is some sort of corrosion?

If I am ever able to isolate the problem, I will post the info.

[time2roll]

"Very slowly, I slid the wand along the barbecue outlet. The little green light, indicating no propane, flashed and beeped every few seconds.

And then: a yellow light! Just for a moment. I narrowed down the search area. Yes! The infamous pinhole leak. The yellow light indicates a low-level leak. A bigger leak would have triggered a red light."

So was it a damaged fitting? Poor connection? Road hazard? No pipe tape? Defect in the pipe? External damage?

[rexlion]

Double post, thanks rv net...

[rexlion]

I am glad you were dogged in your search. Wouldn't want your wife to have reason to get catty. 😉

[Old-Biscuit]

Buy a bottle of that bubble solution kids use to make bubbles...Dollar General, Dollar Tree, 99 cent Store etc

Cheap and great for using as soapy solution to do leak checks with



Opening the Propane Service Valve will NOT damage the regulator.
It CAN cause the Excess Flow Device to trip which then limits the flow of propane.
Opening it slowly allows downstream/upstream pressure to equalize w/o tripping the Excess Flow.
If tripped...close Service Valve...wait 30 seconds and then SLOWLY open Service Valve again



Propane Service Valves should be fully Open or Fully Closed.
No 'partially open'

[road-runner]

We had a really, really slow leak in our home propane range that took me a couple of years to find. There was an occasional bad smell that I never even realized was propane for a long time. Initial work with a gas sniffer yielded nothing. It was only a fluke that somebody opened the refrigerator door (a few feet away) while I had the sniffer running and got a very faint hit on it. I think what happened is that the gas built up under the range, then the draft from opened refrigerator pushed it out from underneath. It was leaking where a straight pipe was threaded into an elbow. With the range opened up and soap solution applied, the bubble blew up at a rate akin to watching paint dry or grass grow.

[4aSong]

You went to great extreme to isolate the leak and saved having to take it to a shop. I will take note of your approach for finding the leak should I ever need it. Thank for finding the time to document your methodical approach and sharing it with fellow RV's.