LP generator hose leak + Propane Testing Info

onemanvan

Member
I ran this leak down test:

1) Turn on LP at tank
2) Let system pressurize
3) Turn off LP at tank
4) Wait 24 hours
5) Turn on one of the stove burners
6) Confirm gas hisses for 30 seconds or more...

Mine did not pass this test - no hiss at all...
I used an Inficon Gas-Mate to trace down the problem.
I isolated the problem to the 'Rubber LP generator hose'.
Where the hose meets the generator it bends 90 degrees in the space of a few inches!
I believe this was too much stress for the rubber itself and/or the brass-rubber connection.
At any rate - where the rubber meets the brass there was a leak!
I removed the hose - capped off the line - and I'm running another 24 hour test...
I'll replace the hose and try to squeeze in a 90 degree brass elbow to relieve the stress.
 

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MrTomacco

Mr. Tommaco
Re: Rubber LP generator hose leak

Are the gas detectors typically available for rent somewhere or are they cheap enough to buy?

Rob
 

onemanvan

Member
Re: Rubber LP generator hose leak

They cost about $200 - I'm not aware of any place that rents them... I happen to have one because in one of my previous lives I was an RV repair technician... I'm just an old retired codger now:)

BTW: I re-ran the 24 hour leak down test with the genset line capped off at the tee and it passed the test with flying colors! Stove burner stayed lit for over 4 minutes on residual pressure! That confirms I'm on the right track and there aren't any leaks in the lines that Westfalia expertly installed!

One other note: I also found a leak at the test port on the carburetor - tightened down the plug and stopped that leak as well...
 
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onemanvan

Member
Re: Rubber LP generator hose leak

If your'e ever in Benson Arizona feel free to look me up and I'll share with you whatever you need!
 

onemanvan

Member
Re: Rubber LP generator hose leak

I couldn't squeeze a 90 degree brass elbow into this space, so...
I made a 90 degree elbow out of 3/8 soft copper tubing and installed a new hose.
Test ran the generator - checked for leaks - started another 24 hour leak down test...
Yes, you can borrow my copper tubing bending and flaring tools too :)
 

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onemanvan

Member
Re: Rubber LP generator hose leak

My propane system now passes the leak down test!
Replacing and re-routing the hose to the generator fixed the problem.

Footnote:

To further illustrate the incompetence of the Airstream upfitters/installers.
I found teflon tape on the flare fittings they used...

Copper Handbook

"No material (e.g., pipe joint
compound) should be applied to the
mating surfaces of the flare fitting and
the flared tube end before attaching the
flare nut to the fitting body."

Page 53 - Copper Tube Handbook, put out by the Copper Development Assn. http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf
 
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OldWest

2004 T1N Westfalia
Re: Rubber LP generator hose leak

Thanks.

Also, someone posted awhile ago to check the routing of the propane line above the driveshaft. In that case, the propane line was not properly secured and was dangling and rubbing on top of the driveshaft. A circular line on the driveshaft could be seen where the propane line was touching the driveshaft. .
 

OldWest

2004 T1N Westfalia
Re: Rubber LP generator hose leak

Not related.

In the photo above to the right, you can see the gray water valve by Valterra--the square and the square bracket. You can see that a cable is in the middle of the large open square bracket area. After taking proper precautions like jackstands, you can spray some silicon lubricant where the cable runs through the square bracket opening. If you can't see, just spray everything. Had a gray water tank leak from the hose and finally figured out that the gray water valve wasn't closing because of a binding cable. Spraying thus area and the gray water tank valve handle area solved the problem.
 

onemanvan

Member
Re: Rubber LP generator hose leak

The place where mine was leaking is 'hidden' behind a support strut for the generator.
This makes it very difficult to spray soapy water on the place where the rubber meets the brass.
Much less see the results...
In lieu of a leak detector you might try this:

1) Stop off at your favorite hardware store and pick up a 3/8" flare cap and plug
2) Loosen flare nut on LP hose at the tee and cap off the tee
3) Run a leak down test - if it passes goto step 4 - otherwise you've got a different problem
4) Reconnect the LP hose to the tee
5) Loosen flare nut on LP hose where it meets the generator and plug the hose
6) Run a leak down test - if it fails replace the hose - otherwise the leak is in the generator...

Attached images of cap and plug:
 

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