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Thread: Motor back together but have a problem

  1. #1
    Ultra21
    I rebuilt by BBC after losing oil pressure last month and put it in this past Sunday. I'm running hydraulic lifters and ran it at about 1800 - 2000 rpm for 30 minutes to break in the cam and everything sounds great! I finished puting everything together and took it out tonight to Pudingstone for a test drive.
    Oil pressure was around 40 at idle and 65-70 at rpm. Ran for about an hour with water temp around 130 deg. Everything great until I took it up to 4000 rpm and ran for about 10 seconds and oil press went to 0.
    I do have the fuel pump shut off but the pump kept running so it must not have gone to 0 like the gauge read. Looked in the valve cover with it running and there's oil splashing so I thought it might be the gauge or sender. Trailered it and at home I pulled the sender and put a mechanical gauge on it. 10 psi at idle and 25 at rpm (?) What would make it drop so low? engine sounds great and strong.
    New Milidon high volume oil pump, new cam, lifters, valve springs, bearings, rings. Any info on what could cause this? It's a Gen V 454 and does have dual external oil filters.

  2. #2
    GofastRacer
    Sounds to me like the pickup fell off, when you're just idling the pump may be partially submerged in oil that's why you're gettin low pressure??..May be wrong though!..

  3. #3
    Ultra21
    Sounds to me like the pickup fell off, when you're just idling the pump may be partially submerged in oil that's why you're gettin low pressure??..May be wrong though!.. The pickup has a welded bracket that mounts to one of the main bolts and is pressed in pretty tight. It's not welded in but I figured with the tight fit and bracket it should be fine. I'm probably going to have to pull the engine again and will check it. Does anyone know if the bypass valves could have something to do with it?
    Thanks!

  4. #4
    Hallett19
    dude, you could have wiped your bearings .... I had a similar problem with lifters, but I dont think lifters would cause an oil pressure drop that bad, lifters would start chattering after the oil pan was sucked dry from my high volume oil pump/low volume oil pan. It was a mess, engine would hit 4400 rpm, stay for a second then drop 1500 rpms, awefull chatter, then back to 4400 rpms again... then, eventually, the oil press. would get lower and lower, so when I took the motor apart, the bearings were garbage.

  5. #5
    Ultra21
    high volume oil pump/low volume oil pan I'm hoping that's not the problem but my pan is stock and was cut and welded about 1" shorter to fit in the boat by the builder. It holds about 6.5 qts with 2 filters. Wouldn't take much to suck it dry.

  6. #6
    Hotcrusader76
    Ultra21:
    I rebuilt by BBC after losing oil pressure last month and put it in this past Sunday. I'm running hydraulic lifters and ran it at about 1800 - 2000 rpm for 30 minutes to break in the cam and everything sounds great! I finished puting everything together and took it out tonight to Pudingstone for a test drive.
    Oil pressure was around 40 at idle and 65-70 at rpm. Ran for about an hour with water temp around 130 deg. Everything great until I took it up to 4000 rpm and ran for about 10 seconds and oil press went to 0.
    I do have the fuel pump shut off but the pump kept running so it must not have gone to 0 like the gauge read. Looked in the valve cover with it running and there's oil splashing so I thought it might be the gauge or sender. Trailered it and at home I pulled the sender and put a mechanical gauge on it. 10 psi at idle and 25 at rpm (?) What would make it drop so low? engine sounds great and strong.
    New Milidon high volume oil pump, new cam, lifters, valve springs, bearings, rings. Any info on what could cause this? It's a Gen V 454 and does have dual external oil filters. What type of oil are you using?
    I ask because if it's the wrong viscosity then after the oil heats up it tends to cause a pressure drop. Just my 0.02
    [ July 16, 2003, 10:55 PM: Message edited by: Hotcrusader76 ]

  7. #7
    Moneypitt
    Hate to say this, but the milodon HV pumps leave alot to be desired. I installed a new one in a BBC and wiped out the mains in less than 5 minutes. After tear down, I looked at the pump. The clearance between the gears and the cover are suppose to be .002-.0025, and the cover should be square to the pump body. my new milodon pump was .007 at one end and .003 at the other end. really loose, and out of square. As for your problem, take an oil filter apart, look at what is trapped in the folds, see if its magnetic,(steel/cast iron), copper bearing material in the filter will give you a hint of what happened, but open up the oil pump for sure. If it has an arc on the cover, its not square to the pump. If it has a circle in the cover, your distributor/oil drive shaft, may have been bottoming out the gear. Be sure the dist. bottoms on the manifold, (without a gasket), to ensure that the pump isn't jammed against the cover when the gasket is added and tightened down..Sorry to hear about your misfortune.......Moneypitt

  8. #8
    HBjet
    Could he just have not enough oil in the pan? I remember Cyclones old motor had a problem where the PSI would just drop to zero of you where on the gas for any period of time (4-5 seconds) It turned out his dip stick wasn't the correct one for the pan and he just had too little oil in the motor.
    I would pull the filter and cut it up to see what you find. If everything looks good, drain the oil and see how much comes out.
    I run a Melling HV oil pump and at idle I'm around 65psi, 90psi when I'm on the gas. Over the winter we are going to make a change to bring it down to about 80psi when on the throttle and install an oil temp gauge.
    Good Luck and keep us posted
    HBjet

  9. #9
    TX Daytona
    I'd be looking for an oil pan, but also check the shaft between the distributor and oil pump as well. Use a good after market shaft not one of the factory jobs with the plastic sleeve on it.

  10. #10
    Ultra21
    What type of oil are you using? I'm using Valvoline 10W 40 as recommended by the shop that did the crank.
    Thanks for the responses! Looks like I'll be busy this weekend after I cancel my reservations in Laughlin
    Anyone know where I can get a larger oil pan that is short enough to fit in a jet boat? Or will it be easier to modify mine? I'm not sure about the baffling so would probably want to buy one.

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