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Primus 5 Leak

Discussion in 'Fettling Forum' started by BradB, Nov 13, 2017 at 11:26 PM.

  1. BradB

    BradB United States Subscriber

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    My Primus 5 seems to have developed a leak. It was working fine for the several months I have owned it. It started burning down at the priming pan which caused an under burn. I replaced the jet and the washers on the burner, on top of the priming pan and underneath. Not knowing quite what to do, I put the gray lead (??) washer on top and the orange fiber looking one on the bottom. I also added a brass mesh screen in the burner tube.

    The burner burned normally on low pressure for about 30 seconds to a minute and then would develop a flame at the primer pan. I kept tightening the burner and watching it closely. It would burn normally and then I could see liquid kerosene seeping out on top the pan. When enough collected it would ignite. I kept tightening until now it will burn normally. At higher pressure, about 12 pumps, I can still see some seepage but it is not leaking fast enough to collect enough to ignite. It is very close to igniting but I did burn it for about 10 minutes under high pressure.

    I have two questions. 1) Is the type of gaskets I am using correct? 2) How tight do you tighten the burner? Right now I can't make it any tighter but I can still see the seepage. The "stain" you see on the burner nut is seepage.

    IMG_0872.jpg
     
  2. Ray123

    Ray123 United States Subscriber

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    I would replace the lead with a fiber washer since that is where the leak seems to be. Some people report good results with lead burner washers but I feel the fiber washers seal better.
    Brass mesh in the burner tube is probably unnecessary. Maybe it's simply a loose mesh strand is preventing the washer from sealing?
     
  3. BradB

    BradB United States Subscriber

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    Before I added the lead washer I tried two new fiber washers. It didn't stop the seepage. They also did not survive when I took them off. The brass mesh was an afterthought, but the stove was leaking before I put it in. The addition was an idea from Bernie Dawg on my Optimus 1S, so I thought it couldn't do any harm. Adding it seemed to stop a chuffing action in the 1S.
     
  4. hikerduane

    hikerduane United States Subscriber

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    I've noticed that a few priming cups have a larger hole, leaving a gap around the threads, which two heat proof washers won't seal it seems. Try just one, I think I've placed it under the priming cup. Seems the more logical place. I believe i read to soak washers in water for a bit. I've experienced the exact issues you describe except for the pooling in the priming cup. Mostly vaporized fuel, see wisps around the joint.
    Duane
     
  5. hikerduane

    hikerduane United States Subscriber

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    Center the priming cup best you can if there is a gap around the riser so if using one washer, it can seal the bottom of the burner with the riser.
    Duane
     
  6. BradB

    BradB United States Subscriber

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    Hmmm, I forgot the trick of soaking the fiber washer. Guess I will try that next, as well as other good hints here. It actually is not pooling up but just the tiny bit of seepage builds on the nut until it ignites.
     
  7. Tony Press

    Tony Press Australia Subscriber

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    @BradB

    As advised above, use two fibre washers. Don’t overtighten. I go through the ritual of 1. Hand tighten (don’t force); 2. Use a spanner to tighten firmly (Svein don’t force); 3. Burn for a while and observe; then, 4. Use a spanner to tighten a little bit more, but only if it moves without much force.

    Cheers

    Tony
     
  8. BradB

    BradB United States Subscriber

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    I soaked two fiber washers in water for 1 1/2 hours. Then I hand tightened the burner. The priming pan was indeed much larger than the riser and it is not easy to keep it centered, but I did the best I could. I just did a 10 minute test burn and it did not seem to leak or ignite accidentally. Good so far.
     
  9. Simes Reserved

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    @BradB I have to admit I've not attempted this on any fixed leg Primus/Optimus, but I have a Valor Pakaway with a spirit cup which spins like a top and is completely gas tight.

    My assumption from the Valor is the packing is there just to clamp the cup. If you are in the middle of fettling would it be worth trying the connection without the cup and see what happens? The other conclusion may be that you have too much packing and it's stopping the two sections sealing correctly. It wouldn't take much washer thickness to keep you from tightening the pieces together.
     
  10. nmp

    nmp United Kingdom Subscriber

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    Having similar problems myself I have tried as many combinations of washers as you can imagine both wet and dry and the problem still raises its ugly head every now and then. I am waiting for new washers from fettlebox to try and solve the problem on a Radius 17.

    Going to try one soaked washer tightened and then allow it to dry before firing.

    I find that firing it up with damp washers the washer dries out fast and the joint leaks. So I thought I would give it a go this way checking tightness before firing? Any more ideas?
    Nick
     
  11. BradB

    BradB United States Subscriber

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    I just cooked soup on my Primus 5 with no problems. If the problem reoccurs, I might try some of my Master Plumbers TFE paste. It is heat resistant and does not harden permanently. I have used it very successfully on several Coleman stoves.