Very slight propane smell

Don't know if we have a problem but would like your thoughts.  Every once in a while, we smell propane when close to the tank.  My wife has a keen sense of smell and notices it more than I.  Obviously the previous owner also smelled the propane since he had the unit looked at.  Three service facilities looked at the tank and did not fine a leak.  One of the three was the company we used for the PDI.  That was costly and while they didn't specifically state that they did a leak test, I'm assuming they did.  (I'm calling tomorrow to confirm)  I have sprayed soapy water around the connections and nothing.  No bubbles.  I've read that propane tanks can produce a smell when they're low on propane and right after they've been filled.  The tank probably had about 3 or 4 gallons when we filled recently.  So if 3 or 4 gallons would be considered low then that might explain that.  And we haven't used propane other than to run the refrigerator since filling the tank about a week ago.  So maybe we're still getting the just filled smell.  In any event, I'd like some confirmation that this is normal or suggestions on what we do next. 

As an aside and maybe related, based on what I know, the propane regulator may not be mounted correctly.  From what I read, the regulator is supposed to vent downward.  It does not.  It vents horizontally. 

One other issue on propane.  The gauge is broken.  It was taped to the unit when we bought it, but fell off after messing with it a few times.  I don't know how these work but recall seeing that they twist lock in place.  If so, I'll probably tape it again until I can find a replacement gauge.  If they do not twist lock in place, how are they attached?  The gauge has two wires that probably send info the the display inside the coach.  It would seem like a pretty easy replacement if that's all there is to it. 

You don't say how old or what type of RV you own, but since you mention a previous owner I am going to guess it is at least a few years old.  If that is the case I would suspect the propane regulator, in particular you may have a pin hole in the rubber diaphragm of the propane regulator.  I had a similar issue, just catching a faint whiff of propane when there was very still air, replacing the 15 year old propane regulator seems to have solved the problem for me.

for basic concept of how a gas regulator works see this video https://www.youtube.com/watch?v=n4DDnoMAHY8  your propane regulator will be a bit different, but fundamentals are the same

It's an 05 Pace Arrow.  We've had it for about 2 months.  Not sure I sprayed soapy water on the diaphragm.  Guess I'll have to give that a try. 

There is very small drain/vent hole on the bottom side. I had one leaking there/

Hi garyb1st and all,

Since you just had it filled, wondering if it is warm or hot in your area. It could be that the tank is venting due to expansion of gas.

I don't think "getting low" can cause any propane smell.  Re-filling the tank, though, always involves opening the vent/overflow and some vapor escapes (by design). There may be a brief lingering smell, but it should dissipate within minutes.    The tank will also vent some vapor if overfilled, especially on a very hot day. Again, by design.

As others stated, the regulator can be a source of a tiny leak. It too has a vent hole in the body and an internal leak will vent a tiny bit of LP vapor. If in doubt, just replace it. They aren't very expensive and it;s an easy enough DIY if you have a couple wrenches.

I would not anticipate an actual tank leak (a rust pin hole) in a 2005 vintage coach, but I suppose anything is possible.

  Check the "spitter" valve,, should be finger tight, many times the tech won't get it tight enough when filling.>>>Dan

utahclaimjumper said:

  Check the "spitter" valve,, should be finger tight, many times the tech won't get it tight enough when filling.>>>Dan

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I Googled "spitter" valve and came up with nothing. Is that the small screw which the Tech backs off with a screwdriver prior to filling and then shuts it with a screwdriver when propane comes out of it. If it is, I've never seen it just finger tight. They always use a tool to operate it. Maybe being just finger tight is the source of the leak.

While it's been pretty hot here we've smelled gas when the tank was pretty low.  Maybe 4 or 5 gallons.  So I don't think expansion would be the problem with only a few gallons.  I'll pick up a regulator when I'm at a RV store.  Camping World didn't have the right one when I was there a few weeks ago.  I'm trying to find a horizontal regulator with a vent in the down position. 

Thanks for the responses. 

Every time I try to excuse the smell of propane as normal, I end up finding a leak eventually.  Two were failing regulators, one was a hard pipe fitting that leaked from the factory and was repaired under warranty.

Regulator venting could be at issue as you mentioned the vent orientation.  However, there are "horizontal" and "vertical" vent regulators.  If you can get the part/model number and mfgr off the regulator, you should be able to find it on the Internet where it should indicate the vent mount orientation.

An upright tank has the valve you describe that uses a screwdriver,, the laydown tank has a knurled knob above the fill fitting.>>>Dan

utahclaimjumper said:

An upright tank has the valve you describe that uses a screwdriver,, the laydown tank has a knurled knob above the fill fitting.>>>Dan

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Got it. Thanks Dan.

Finally found the leak.  It was leaking from the regulator itself.  It didn't occur to me that the regulator could be bad so all I never sprayed soapy water on it.  The previous owner stated he had a new regulator installed because he was also smelling gas.  The unit must have been bad from the get go. 

Gary RV_Wizard said:

I don't think "getting low" can cause any propane smell. 

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I have not been able to figure out the science behind it....
but we have a non-vented LP fireplace in our house.  No chimney, no stack.... not vented in any way to the outside.
There is no appreciable smell normally....but when the tank gets low, it does emit a fairly strong smell as it burns.  Smells sort of like a propane leak.
refill the tank, the smell goes away.
I guess it's a function of pressure.

I asked the LP gas man about it, he said "it's normal"....but didn't (or couldn't?) go into detail

My understanding is that the Mercaptan (purposely stinky additive) gets more concentrated as the LP level decreases thus the increased smell.  It is placed in there to give it that "find the problem" stink.

What Old Racer said... the  Mercaptan  settles to the bottom of the tank and as you start pulling propane from the lower level more of it is sucked up and gets burned. Higher concentration, higher smell. Adding propane to the tank changes the concentration of gas to Mercaptan    blw2....  Your supplier should have had some idea of what was going on.

Finally found the leak.  It was leaking from the regulator itself.

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Gary, we had a system air leak and the Monaco techs struggled to find it over several rallies.  They found several small ones but the air kept leaking.  At one point they put in three new vacuum "thingies" for our step cover.  The original leaked and two more fresh out of the box also leaked.  The fourth didn't and has worked just fine since installed.  The head of service said they knew they had a supplier problem and this proved it.  The final leak, however, was the dashboard gauge itself and the only reason we found it was that one of the techs had to work under the steering wheel to tighten something and suddenly he shushed us all.  He could hear air escaping near his head and just put his ear against each gauge until he heard it clearly and we all confirmed it.  The last thing we expected was the air gauge!  So sometimes it's the most simple explanation and often not expected.

ArdraF