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Thread: BBF oiling problems

  1. #1
    llepd
    I have a bbf that keeps losing oil pressure, after hard runs. spun bearings on one last year. changed to 10 qt rr sump pan, high volume pump, windage tray and last weekend lose oil preasure again have not torn down yet but suspect same thing. Any ideas? I'm new to jet boats. here is my theory jets are not made for long runs and when catching air it over loads the engine causing bearing failure. open for ideas. Don't what change to chevy this year.

  2. #2
    hack job
    do you have any idea what your oil temp is after your wide open runs? also what kind of rpm are you running it at. on a side note loading and unloading your pump is not goof for the motor or the pump.

  3. #3
    llepd
    do you have any idea what your oil temp is after your wide open runs? also what kind of rpm are you running it at. on a side note loading and unloading your pump is not goof for the motor or the pump.
    DON'T HAVE OIL TEMP GAUGE, WATER TEMP 140 TURNING 5000.

  4. #4
    Danhercules
    In my old boat, (BBF) when I would make WOT runs for 2 min I would watch the oil press. After a bit the pressure would drop a few psi, I then let off and cruised nice a slow to cool the oil back down. Oil temp would be a good idea.

  5. #5
    Senior Member
    Join Date
    Feb 2009
    Location
    Northern Illinois
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    1,090
    Check your crank journals, there are some cranks out there that are not exactly round, and really mess with your oil pressure.

  6. #6
    Senior Member
    Join Date
    Feb 2009
    Posts
    4,169
    To get to the root of your problem, an little more detail is needed. When you say you "lose" oil pressure, how low does it go, does it come back up as the oil cools, and how many quarts are you running in your 10 qt pan? It often helps running it a quart low to keep from aerating the oil. Your problem can be that, oil temp breaking down the viscosity, running a Fram filter, or all of the above.

  7. #7
    llepd
    To get to the root of your problem, an little more detail is needed. When you say you "lose" oil pressure, how low does it go, does it come back up as the oil cools, and how many quarts are you running in your 10 qt pan? It often helps running it a quart low to keep from aerating the oil. Your problem can be that, oil temp breaking down the viscosity, running a Fram filter, or all of the above.
    OK last time oil pressure gauge was at 0 shut it down and let set restarted it pumped back up after few seconds. running 9 quarts oil, checking oil doesn't seem deluted, i'm running fram filter, 20-40 valvo racing oil. limped home put trailer seemed to have oil preasure until you put loas on it and it would drop. goin to put in water tomorrow just to check it again but I'm afraid it is to late.

  8. #8
    Senior Member
    Join Date
    Feb 2009
    Posts
    4,169
    If it were me, I would replace the filter with something OTHER than a Fram (I use Purolator), cut the old one open and inspect it.
    I assume you didn't have the pressure problem after you replaced the pan and that when you put it on you checked to make sure you had 3/8" clearance between the pickup and the pan.

  9. #9
    058
    OK last time oil pressure gauge was at 0 shut it down and let set restarted it pumped back up after few seconds. running 9 quarts oil, checking oil doesn't seem deluted, i'm running fram filter, 20-40 valvo racing oil. limped home put trailer seemed to have oil preasure until you put loas on it and it would drop. goin to put in water tomorrow just to check it again but I'm afraid it is to late.
    There can be alot of reasons for losing oil pressure and bearings. Clearances too tight? Mains not in alignment? Crank not ground and polished correctly? Rods not in good condition? Engine detonating? Oil not getting to the mains due to internal leakage from a missing plug or worn lifter bores? Wrong bearings? Oil breaking down? The list goes on and on. Spinning the engine 5K should be no big deal but some provisions must be made. Start with the block and have it align honed, have the crank ground and polished by a good shop that can do it correctly[should be ground in the rotation of the engine and polished in the opposite rotation] get a good set of steel rods[Crower, Oliver, Carrillo etc. or if you are on a tight budget a set of Eagles or Scat rods will work just fine for your application. Set your bearing clearances as followed: Mains: .003-0035" Rods: .0025" rod side clearance: no less than .020" Have the block zero decked to help prevent detonation,check your tune up and confirm your timing marks. Start with 34-36 total timing depending on the cyl. head you are running. Make sure the engine is getting enough fuel so not to cause lean out. That should give you something to go on. The BBF is not prone to bearing problems as many have run as much as 9000 rpms with a cast crank and a passenger car block for 25 seconds at a time [truck pullers] so your jet boat application should be a piece of cake.

  10. #10
    victorfb
    FRAM?????????? Yikes!!!!!!!!!:jawdrop: i know what i would change first.

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