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  1. #1
    Lieutenant Junior Grade marc c's Avatar
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    Default Trim Pump Vent Screw

    Hi There. Just removed the Vent Screw on "my new to me" used trim pump and noticed that it looks like a #10 Sheet Metal Screw with a Blunt Nose.

    Just wondering if that's the correct screw for the vent?
    The fill screw is a machine thread.

    Also, I need to replace the plastic down hose (lower circled fitting) that goes from the pump to the trim indicator piston. What kind of pressure is on this hose?

    Thanks


  2. #2
    Petty Officer 1st Class
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    Default Re: Trim Pump Vent Screw

    everyone knows sheet metal screws aren't meant for engines bit some idiot zipped it in there. personally, i would use a tri-tap and rethread the hole to, maybe the next size larger, but one that fit correctly. some may differ and say, if it doesn't leak, it's ok. you're call. about the trim hose, i can't help you there, but i'm sure someone here will, sooner or later. good luck!

  3. #3
    Vice Admiral Reel Poor's Avatar
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    Default Re: Trim Pump Vent Screw

    Pump pressure is 400 to 600 psi on down side, and 2200 to 2600 psi on the up side.
    Of those who receive good advice, only the wise will profit from it.

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  4. #4
    Lieutenant Junior Grade marc c's Avatar
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    Default Re: Trim Pump Vent Screw

    Thanks for the prompt replies.

    Anyone know what size fastener should be in the vent hole?

    Also, if it's a machine screw - how does it vent?
    1974 Glastron V-179, Mercruiser 140
    1984 16.5ft. Alumarine Sealark side console with 82 Merc 50
    Homeport - Lac du Bonnet, MB, Canada
    I've used Fram oil filters in all my junk for 35 years-no problems

  5. #5
    Admiral ziggy's Avatar
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    Default Re: Trim Pump Vent Screw

    if yer gonna tap that hole. i'd be concered about where the metal shaveings from the tapping process go. like into the trim pump maybe. that might not be to good for it.....i think if it were mine, i'd just leave the sheet metal screw in it and leave well enough alone...it's just a vent......
    'Lime Time'
    1975 AristoCraft Nineteen
    Mercruiser 165hp (chevy 250 L6), MC-1 drive

  6. #6
    Petty Officer 3rd Class
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    Default Re: Trim Pump Vent Screw

    Marc C,
    On http://dougrussell.com web site, I found the reservoir fill plug part number 392-7728 for $4.39 each. I looked under Mercruiser Alpha 1 "Hydraulic Pump Prestolite" parts listing.
    Crawdadric

  7. #7
    Lieutenant Junior Grade marc c's Avatar
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    Default Re: Trim Pump Vent Screw

    Quote Originally Posted by crawdadric View Post
    Marc C,
    On http://dougrussell.com web site, I found the reservoir fill plug part number 392-7728 for $4.39 each. I looked under Mercruiser Alpha 1 "Hydraulic Pump Prestolite" parts listing.
    Crawdadric
    Thanks for the link. I found some part numbers for an older model that might help me out.
    1974 Glastron V-179, Mercruiser 140
    1984 16.5ft. Alumarine Sealark side console with 82 Merc 50
    Homeport - Lac du Bonnet, MB, Canada
    I've used Fram oil filters in all my junk for 35 years-no problems

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