Strange noise!

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Karl

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Since being parked continually except for an occasional trip to the dump station, I've heard what sounds like a small sonic boom once in a while, every few weeks. Nothing rattles or shakes, the coach doesn't shift or sink, but it sure gets your attention. My jacks are down but just enough to level; not any real weight on them, boards under the wheels (bowed slightly but not broken). It's not anything propane related, gasoline and water tanks about 1/4 full. Thought very hard about the jacks, but since there is no movement or shaking of the coach I kinda ruled that out - maybe too soon.

Any suggestions what it might be? 
 

Ned

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Does it happen when there is a large temperature change?  If so, it could be something expanding and contracting under tension.

Or it could be a sonic boom, look for high flying planes :)
 

Tom

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A couple of nights ago Chris asked me to turn the volume down on the TV because she could hear some loud noises I hadn't noticed. Sure enough, they sounded like sonic booms. Then we noticed fireworks above the houses in the distance. Yesterday, a friend from that part of town stopped by and mentioned the very loud fireworks in her neighborhood on the night in question.
 

JerArdra

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Karl,

On our 1999 Windsor sometimes an overhead cabinet would slam down with the same effect.  It had upper cabinet doors that hinged upward and were spring loaded so when they slammed down it was a LOUD boom.

JerryF
 

Terry A. Brewer

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Karl

>>I've heard what sounds like a small sonic boom once in a while, every few weeks.<<

I have read on other forums that it was caused by HWH jacks or fuel tank expanding/contracting..."Tin Can Effect"


Terry
At Great North American Rally, Redmond, OR
 

Karl

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Thanks for all the suggestions.

Jerry, it's not a cabinet door for sure, but good thought.

Ned and Terry, - very possibly, 'cause we've gone through some large temp. differentials and the gasoline tank had a lot of air inside. Could very well be oil canning. If it was the jacks, it was so small that marking them with a Sharpie and looking for a change the next time it happened would probably not show any change. Like I said, I couldn't detect any vibration, settleing or shift.

Tom, also possible, but I would have expected more than one and darn, I sure would have liked to have seen them. Also, one of them came mid-day, so I suspect it wasn't a black powder burst.

For now, I'll hope it was oil canning and not my frame deciding to do a backbend. If I don't make it to QZ next time around, you'll know it was something more serious ;D 
 

JerArdra

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Karl,

I had one other idea.  Twenty years ago I had a MH that had a loud bang and it turned out to be the "overpressure" valve on the propane tank releasing propane.  In my case heat caused this to happen.

JerryF
 

Karl

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Elkhart Lake, WI for the summer. Work at Road Amer
And the 1st prize goes to ..... Terry Brewer! (Huzah, clap, clap, hat tossed in the air...)

I was crawling around underneath measuring for the new exhaust system (finally got it) and lo and behold, it indeed was oil-canning of the fuel tank. Next time I have $600 bucks or so I'll fill 'er up and eliminate the problem ;D It was a lot less full than originally thought - only about 1/8th.

Thanks to you all for the suggestions.
 

DougJ

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PMJI Karl, but what's "oil canning" as in oil-canning of the fuel tank?

Ciao,

Doug
 

Karl

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Doug,

Back in times of yore, ye old oil can was the banisher of squeaky door hinges and hard turning nuts and bolts. No self-respecting do-it-yourselfer would be without at least a couple of them. Shaped more or less like a ball sliced in half; the flat portion being the base and an elongated spout screwed into the top center of the round portion, a few pushes with the thumb on the slightly convex bottom would, while inverted, force oil thru the spout to the place desired, and would make a characteristic "pucka-pucka" sound as the base went from convex to concave with each push - thus the term "oil-canning". My gas tank was expanding with increasing temperature, occasionally making a very loud "PUCKA"!  Upon cooling sufficiently, the sides would contract making an equally loud "AKCUP"  (a reverse PUCKA) ;D
 

DougJ

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Oh boy, you can tell I'm not a do-it-yourselfer :).

Come to think of it, I can't remember the last time I held an oil can in my hand.  Mind you, on occasion I am moved to pick up a tool and do a little futzing on our rig.

Oh, and thanks for the explanation.

Ciao,

Doug
 

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