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Thread: 49 panhead oil pressure switch and light

  1. #1
    Join Date
    Feb 2010
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    ***an
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    Default 49 panhead oil pressure switch and light

    hi
    I run my 49 sometime, ,, after 20 or so minutes ride oil light gets on... I thought the swich was no good and changed it.. but same thing happened with new switch.. something wrong with the pump ? or just use thicker oil ( I use 20-50) ? any suggestion please. tks Shin IMG_8121.jpg

  2. #2
    Join Date
    Jan 2006
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    Menomonie, WI
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    Once a Panhead engine gets warm it is not uncommon to have the oil light 'flicker' at idle. That is normal behavior and is Ok. If it stays on solid maybe try 50w oil. I have never used 20/50 in a pan so I am out of my range of knowledge on that.

    Jerry

  3. #3
    Join Date
    Dec 2009
    Location
    Upstate NY
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    I think 20-50 is too light. Like Jerry says, at least 50 weight. I run straight 60 in my pan, and the only time the oil light ever came on when the bike was at idle was when the clearance between the rocker arms and the blocks wore out of tolerance. Took the blocks out and dressed them, reamed the cradle hole for the rocker arms and re-installed. No problem since. I think the reason why I never get even a flicker is because I updated the pinion shaft and oil pump gear in the timing case many years ago.

  4. #4
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    Jul 2006
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    Central Florida
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    Using 20W50 in your Panhead? That twenty minutes is the time it takes for the 20-wt to thin to about the thickness of water (H2O) and stop lubricating. Get that stuff out of there, and run either straight 50-wt or 60-wt in your crankcase! That twenty-weight oil is not doing the job of lubricating your engine. Except wearing it out prematurely.

    Straight 50-wt oil is the only thing sold in a modern Harley-Davidson "boutique" that my pre-war Harleys can use. Fifty in the Winter and 60-weight in the Summer.

  5. #5
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    Jun 2005
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    Northern Colorado
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    I use nothing but straight 60 in my Panheads. When the 20w50 came out back about 1981, the MOCO indicated it would be fine for all Big Twins, but we found that to be inaccurate...
    VPH-D

  6. #6
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    Nov 2008
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    Virginia
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    I agree on the either 50 or 60 wt conclusion. I have a number of antiques from 1933 on and run 60 in all of them in engine and tranny. This is just an extension of the "endless oil debate" but IMHO I stick with what has worked for 45 or so years for me and all the stats and tech sheets isn't going to change my mind and my 45 plus years of experience. Some will disagree and say I know nothing but I know what works!

    Tom (Rollo) Hardy
    AMCA #12766

  7. #7
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  8. #8
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    Oct 2016
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    1962 Panhead, 48,000 miles and counting, never had any thing but 20W-50 in it, rebuilt to modern clearances, runs great.

  9. #9
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    Feb 2010
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    Quote Originally Posted by pan620 View Post
    1962 Panhead, 48,000 miles and counting, never had any thing but 20W-50 in it, rebuilt to modern clearances, runs great.
    Mine too! 30 to 110 degree swing!

  10. #10
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
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    4,143

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    This shouldn't be an oil thread, Folks!

    It should be about Hdhikaru's original question, as his instincts were good.

    If it ain't an OEM switch, it invariably switches at unknown higher pressures, signalling a false alarm at low RPM.

    The truly anal measure them. (Repop in attachment.)

    ....Cotten
    PS: Once upon a time, I lost a wrench, and tooled my 86" Pan slowly around my small town looking for it, *quite* warm, with a 4 psi OEM switch 'on' constantly.
    There were no protests from the motor (and I could still hear back then)...
    Even a veteran pump provides the necessary flow, with pressure indicating only restriction.

    So its hard to call the oil light an alarm,.. unless you are rolling down the road!

    PPS: The photo attachment protocol for this site annoyed me at first, but since eight out of ten of my postings have already been uploaded and posted, its appreciated. Saves data for edits.
    Attached Images Attached Images
    Last edited by T. Cotten; 12-20-2018 at 03:54 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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