Losing oil pressure, and what we found...
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Losing oil pressure, and what we found...

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    Senior Member Nordic78's Avatar
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    Default Losing oil pressure, and what we found...

    Hey jet boaters, my Brother in law's 21 silhouette deck, 454, mild build pump gas motor seemed as though he was losing oil pressure, as it came up to operating temp at cruising RPM of around 3500 he would get approx 10 to 20 psi oil pressure which is pretty low, when at idle pressure would come up to around 30 so we pulled the motor, pulled the pan and what we found had me scratching my head, the face of the oil pick up had formed a noticeable circle at the bottom of the pan, now the pick up is welded which makes me wonder if this is just to close to allow any oil to the pick up, we measured around an 1/8 inch between the pick up and the pan, plus the pump is a melling HV which would make matters worse if the void space for oil to collect before pick up was too small to begin with, now we did not build this motor so I have no idea how the tube would rotate or get closer to the pan bottom, anyone experience this issue before and what would be the proper clearance between pan and pick up? Thanks bros...

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    Most are 1/4 to 3/8 ,,,1/2 would be max, High volume pumps move the oil pretty well they need clearance
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    Senior Member bville's Avatar
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    I think 3/8 min.

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    Senior Member ol guy's Avatar
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    What pan would be good to know but as we speak the pump is sucking a dry pan creating the drop in pressure. Also that pick-up being that close to the bottom of the pan verifies the theory Not to mention what oil is he running?

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    Senior Member Nordic78's Avatar
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    Quote Originally Posted by ol guy View Post
    What pan would be good to know but as we speak the pump is sucking a dry pan creating the drop in pressure. Also that pick-up being that close to the bottom of the pan verifies the theory Not to mention what oil is he running?

    We looked all over the pan and could not find any numbers to identify the pan, oil is 20w-50.

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    Senior Member Boat 405's Avatar
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    What pan is it? If its a 10 quart box pan. I'd be willing to bet you have too much oil in it, causing the oil to hit the crank and foam and aerate the oil. Try 7 quarts in that 10 quart box pan. I bet your problems go away.

    On the dyno I've done extension tests with this topic. A good way to fix a majority of it is to go to a good quality kickout pan from Williams, Stefs, or Olson. If money is no object go dry sump. LOL. I have a 800 hp 540 that has had an olson kickout pan on it and a Williams kickout pan on it. Both have worked excellent.
    Boat 405.

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    Quote Originally Posted by Boat 405 View Post
    What pan is it? If its a 10 quart box pan. I'd be willing to bet you have too much oil in it, causing the oil to hit the crank and foam and aerate the oil. Try 7 quarts in that 10 quart box pan. I bet your problems go away.

    On the dyno I've done extension tests with this topic. A good way to fix a majority of it is to go to a good quality kickout pan from Williams, Stefs, or Olson. If money is no object go dry sump. LOL. I have a 800 hp 540 that has had an olson kickout pan on it and a Williams kickout pan on it. Both have worked excellent.
    Not thread jacking Im going to run Delo 15/40 oil in my 496 good or bad idea, motor was broke in on that, oil will be changed every trip or 2 being it has a blocked by pass your thoughts on this , I have the Canton no kickout running 7 quarts.
    Slinging Lead on and off the water for over 40 YRS

    82 18' Crusader Tunnel SOLD ,
    00 23' Mako 232 fish killer,SOLD
    78 19' Eliminator Daytona SOLD
    16 19' Predator/Cheyenne

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    'Nother thread jack.

    My mild built 460 does the same on VR1 20w50 and RP 10w40 HPS, but I have the crappy design Milodon 10 qt. pan. It probably doesn't help that the PO told me to make sure and keep the oil level at the bottom of the stick, which took exactly 12 qt. It also slings oil from (I think) around the rear main. I need to get another dipstick and figure out how much oil I should really be running and see if I can't clear up my issues before taking more drastic measures. The crank wants to beat up the chopped dipstick as it is, maybe this is actually why it's so short.

    Good luck with yours Nordic, pls update.

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    Senior Member Nordic78's Avatar
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    I will let you know, oil pump is new Melling standard volume oil pump set just under a half inch from the bottom of the pan, I think we will start at the lower end of the dip stick and trial run to see what type of pressures we get and then add as we go, motor goes in this Sunday and we leave for the the river on Thursday of next week, wish us luck.

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    Good luck!

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