The Infamous Auto Stop Propane Fill Valve.

We live full time in a 1987 32′ Rockwood in New England, starting in November 2011 so Propane is near and dear to our hearts. As we revived and grudgingly updated the quarter century old systems we danced around the 100 pound propane tank and its original fill valve. The only other place that I had seen these is on the VW type II Westfalia campers. Finally we couldn’t fill the tank again. Couldn’t find anyone willing to touch the tank. So we took the least intrusive route and disassembled the Auto Stop Valve and replaced the o-rings. We bought Viton o-rings because that what stands up best to halogenated cutting oils and the like. Never considered that propane boils at -40F. Buna-N is the material of choice because it works well with propane and stays resilient down to -40F. But we managed to keep most of a tank of propane and that was enough to allow me to order a modern 1-1/4 inch ACME thread double check fill valve and a 10% outage or bleed valve for the 80% fill line.

The solution is a lot easier than dealing with this early attempt at a solution without a problem. In the long run the only use that I can imagine for this Autostop valve is to allow operator-free propane tank filling.

The solution to the AutoStop problem is to replace this valve with two new valves, an industry standard double check fill valve and a 10% outage or bleed valve at the 80% fill line on your tank.

In some jurisdictions state regulations require that this work be done by a certified propane technician. Having these parts on hand may make it easier for your certified technician because for his day to day work these are not a high replacement item and would not be a stock item.

Here are the AutoStop patent drawings and description:


About Art

55 years old. By training, ability and experience I am a master toolmaker. My most recent projects include designing and building a process to grind a G rotor pump shaft with four diameters and holding all four diameters within plus or minus 4 microns of nominal. This was an automated process using two centerless grinders refitted to my specifications using automatic load and unload machines plus automatic feedback gauging. I also designed and built an inspection machine to check for the presence and size of a straight knurl on a hinge pin using a vision system for non-contact gauging.
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21 Responses to The Infamous Auto Stop Propane Fill Valve.

  1. Bruce Goldthorpe says:

    Hello Art,
    I need the details for the two valves pictured above. My auto stop valve died on me. The issue is the o-ring which is allowing gas to escape from the weep/bleed hole. I’d like to take your recommendation to get the larger intake valve and the smaller 80% valve. Can you give me the details (name, part numbers, where I can order them, etc.)? Thank you for your help.

    Regards, Bruce Goldthorpe

    • Art says:

      I’m not certified to do any more than post my opinions and what I’ve done. You need to find a propane technician willing to do the work for you. I’ve given the specifications for the fill and vent valves and pictures of the replacement parts, People qualified to perform this up-grade will be able to source the necessary parts and materials. Good luck. I know how it feels to watch your fuel gas float away on the breeze.

  2. Howard Fortner says:

    Propane Tank Fill Valve:
    Manufacturer’s Part #: 1855SD sells these 2 items.
    $35.00 or less
    Good information
    I am not certified either, but I can Google stuff.

    • Art says:

      Yeah Howard. Google or Duck Duck Go is our friend giving us access to more information with great ease. Is there a delicate way to tell people to RTFM? With most things I find there is a certain minimum amount of reading to be done before proceeding and I spend a great deal of time trying not to be painfully blunt with people about their shortcomings. Thank you for your comment.

  3. Albert Caum says:

    I have a fuel tank that was mounted on a commercial truck it is leaking; and when trying to refill liquid propane leaked out No fuel was allowed to enter the tank, after the second try, the valve started leaking with a rather loud hissing noise. I would like to replace it if possible, who would I contact for help on this matter? AGC

    • Art says:

      The best way is to have a propane certified plumber do the job. If you feel that you can do it yourself you can find a new industry standard fill valve and a 10% Outage valve through suppliers on the internet without too much trouble. The Autostop valve is a good design only in that it stops filling when the tank reaches the full line. It has one o-ring only keeping your propane from the outside world, that o-ring fails you lose your fuel. The new fill valves are double check valves so you get that additional safety factor. Good luck, Art.


  4. peter says:

    Thank you so much for posting this information. I was thrilled when I found out someone had the same issue.
    I have an 84 asi riviera vanagon. The 3 gallon tank has this exact valve. Upon filling it started pissing out the weep hole…(2 hours later) I drove it home and pondered…
    So… I will get the new fill valve and install it. Where my confusion lies and question is… Am I reusing this existing valve somehow? Where do i connect my outage port to?
    Do you think I could just replace the 3 “O” rings on the inside valve stem??

    Any advice would be greatly appreciated.

    Peter in Seattle

    • Art says:

      Peter, check with your local regulations before doing this work yourself but, once you disconnect the small vent line, the Auto Stop valve unscrews from the tank. Follow the vent line to where it goes into the tank and you’ll see where to put the new outage valve. You’re local plumber should be able to help you out. Your local Manchester tank dealer can also help you buy a replacement tank, and maybe you can fit a larger tank under your Vanagon. 3 gallons is about 12 pounds and the DOT cylinder for your BBQ grill is 20 pounds.

  5. Mike Fulper says:

    Great info… I just bought a 87 Pace Arrow and the propane tank has this Autostop


    doesn’t leak.. but cant get propane to go in..

    your two pcs… solve the problem… thanks, Mike

    Not one RV service center knows what to do about these Auto Stops…

    saves me buying a THOUSAND DOLLOR TANK….:)


    • Art says:

      You really can’t blame the RV service center. They’re a little gun shy because of the type of people they normally deal with so if it ain’t new they don’t want to touch it. Same for propane dealers. Given a large enough number of used tanks, one of them is going to fail. So they insist on selling new tanks whenever they have to deal with older equipment. As you’ve learned, the AutoStop can be made to work but it’s better for all concerned to replace it with new fill and outage valves. And keep your tank rust free, clean and painted.

  6. Shannon Beasley says:

    Where can I order this part? Could you contact me by phone or give me a contact number so I could contact you. I was given your website info by Carpenters Camper in Pensacola Fl


  7. Jake checani says:

    Hey Art, I gather from the information provided that the new bleeder valve will screw into where the old vent line connected to the tank from the old auto stop valve. Do you mean that one must drill a no.54 drill bit into this area to make this new piece fit in? Could you just confirm that to clear up my confusion. Thanks for your time.

  8. Wayne says:

    Is there a video somewhere showing the replacement procedure?
    Mine isn’t leaking, but the release button is a pain and not many propane fill personnel know about this old valve. So replacing the old valves with the new valves would make life a little easier.

  9. Kent says:

    I think I’m having the same problem with my 1988 fleetwood. My propane won’t fill. The gas shoots out the bottom through the auto stop.? My valve looks like it’s the same on you have on your site. Looking for suggestions. Feel free to email me too.

    • Art says:

      The AutoStop valve is a dancing bear, the bear dances but not well. Changing over to the standard valve is an easy solution. If you don’t feel comfortable doing it yourself a friendly propane repairman can do it for you.

  10. Rob Turner says:

    Make sure you check with the rules in your state before you remove the autostop and go to a straight filler valve and bleeder. Most states have adopted NFPA54 & NFPA58. Having a autostop is a DOT requirement for all RV tanks and is not optional.

  11. Tom says:

    I have a 85 rockwood 36ft while gas man was tightening his filler hose we broke the threads vavle is DOA were can i find a updated replacement or even a new thank u

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