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Air bubbles in oil purging

BillAllen Member Posts: 103
Just tried purging oil through the beckett burner got lots of air bubbles. Here's what happened boiler was the subject of a flood but the water reached just below the burner. Also customer let the oil tank go to "E". Then since he is selling he added 15 gallons of diesel oil recommended by his oil man just enough to fire boiler for inspection.

So I'm not sure what is causing the air bubbles coming on to the burner. My guess is need more oil or air leak I'm not detecting or the suntec pump is compromised. Any thoughts?


  • STEVEusaPA
    STEVEusaPA Member Posts: 5,672
    With just a few gallons in the tank you may have turned a gravity feed to a lift.
    Either way you have to establish what type of bubbles. What I mean by that is are they from a high vacuum or a vacuum leak.
    Easiest way to check it with a vacuum gauge.
    If it's high leak, there's a restriction. If there is no vacuum it's a vacuum leak--is the basis to start to checking.
    After you determine and fix that, you'll need to properly bleed the fuel unit, and the best way to do that is with a power vacuum bleed.
  • BillAllen
    BillAllen Member Posts: 103
    Thanks for the insight. I do mostly gas very little oil. The bubbles are not a "foam" like normal heating oil, its more like liquid flow with air but not foam. I think the diesel creates that look.
    EBEBRATT-Ed Member Posts: 11,907
    Probably need more oil. The burner ran the tank empty probably not enough oil to get the prime back. Check the filter and pump strainer and blow out the line. Then try bleeding with a vacuum gage on the pump as @STEVEusaPA suggested.
  • BillAllen
    BillAllen Member Posts: 103
    Thanks EBEBRATT-ED Its got a new filter and cartridge bled at filter diesel was clear and flowing. I have a video too.
    HVACNUT Member Posts: 4,560
    How did you bleed from the filter? From the 5/16 hex screw and its gravity flow?
    One pipe?
    Where's the tank and where is the oil line(s) at the tank? Top or bottom?
    When priming the pump, the oil is spitting rather than solid?
    IMO, even if it was a top fed 1,000 gal tank, adding 15 gallons to the tank should net you approx 15 gallons at the fuel pump. The pick up point doesnt change.
    Certainly seems like a suction leak. Having a run out, especially if old oil lines can disrupt the spooge that was holding that leak together.