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  1. #1
    Join Date
    Nov 2012
    Location
    San Francisco Bay area
    Posts
    6

    Default low oil pressure after rebuild

    We have a power boat with twin Perkins 6-3544M 200HP turbo diesel engines.
    We replaced a cracked block with a new one which came out of a turbo diesel tractor.
    Everything fits perfectly and the engine runs smoothly but I have extremely low oil pressure.

    I have run the engine for hours and brought it to temperature although I've been nervous about putting
    it under any significant load because of the low oil pressure. Pressure should be around 60psi @ 1200-rpm's
    and its more like 10psi... at 1200-rpm's


    Are there any differences in the two blocks which might cause this....any adaptations that need to be made?
    The oil pump is new, as is the pressure relief valve, pistons, oil cooler, bearings bushings, rings gaskets, etc..
    (yes, we plasti-guaged)... Are there internal plugs involved with the routing of the oil which need to be attended
    to? We are stumped.

  2. #2
    Join Date
    Nov 2012
    Location
    San Francisco Bay area
    Posts
    6

    Default Re: low oil pressure after rebuild

    Quote Originally Posted by kimcrwbr1 View Post
    Have you tried swapping the guages are they mechanical or electric.
    Sure did. That is one of the first things we did. They are mechanical and we're monitoring the oil within a foot or two of leaving the engine.

  3. #3
    Join Date
    Nov 2012
    Location
    San Francisco Bay area
    Posts
    6

    Default Re: low oil pressure after rebuild

    We didn't change the oil pan, but we'll look into the pickup.... We did start the engine with the rocker cover off and it didn't splash like we expected... just bubbled slightly.... its possible a problem exists there. We'll ask our mechanic what can be done to remedy this.... Thanks

  4. #4
    Join Date
    Nov 2012
    Location
    San Francisco Bay area
    Posts
    6

    Default Re: low oil pressure after rebuild

    Quote Originally Posted by kimcrwbr1 View Post
    It could be sucking air between the pump and the pickup it should be getting good oil flow out the rockers. I couldnt find a parts diagram can you pull the oil pump without pulling the oil pan?
    No we can't but we have it apart now. We dropped the oil pan and removed the pump and pressure relief valve...

  5. #5
    Join Date
    Nov 2012
    Location
    San Francisco Bay area
    Posts
    6

    Default Re: low oil pressure after rebuild

    This is an update for those interested in how we fixed this problem. We had to do a complete rebuild and by that I mean; because we could not find a short block, we had to buy a bare block and start from scratch. Well there was an internal freeze plug missing. Once we got an air tank and stethescope to quietly listen, we could hear the air escape right around the timing gears... That pretty much solved the problem. The only thing now is, the pressure is at about 50psi and we'd actually like it to be 60psi like our starboard engine. When the engines are warmed up the psi goes down. The port rebuilt to about 30psi and the starboard to about 50psi. We put in a new oil pump as well and was wondering if there was any kind of pump or something that might add the additional psi (or, if thats the right way to look at it)... What is the correct psi range for theses engines by the way? Thanks.

  6. #6

    Default Re: low oil pressure after rebuild

    This is way old and the boat has probably been scrapped but I would like to know what that FREEZE PLUG bit is all about . Have googled without sucess . Is it a welsh plug or a screw in stop plug? And where exactly is it . Its not something I have heard of before.

    EDIT OK found it Its a welch/welsh plug. Name is a myth related to letting the pressure of water freezing out. I assume then it must plug up a drilled oil feed line up the front of the motor and that welsh plug had been blown out ?
    Last edited by tytower; 12-13-2014 at 01:23 AM.

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