Newbie 540 BBC Oil Pressure Question
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Newbie 540 BBC Oil Pressure Question

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    Default Newbie 540 BBC Oil Pressure Question

    Great Forum Guys.
    My question, I have recently purchased a 20 1/2 Ft Carribean with a 540 engine. Do not have many of the build details as the previous owner did not do much engine work himself. Engine has hydraulic roller cam and roller rockers. Under hard acceleration from stop, the oil pressure will drop about 20 psi. It will come back when the boat is on plane and no longer accelerating. Once on plane if engine is held above 4500 Rpm for 3-5 minutes, the pressure will start to drop again. Reducing engine speed to 3500 Rpm or less will let the pressure come back up. The engine came with a box type Milodan pan. I am guessing the first pressure drop is caused by the oil being thrown to the back of the pan and the oil pump is sucking air. The second may be due to windage and or oil not draing back to the pan. Oil temp at this point has never exceeded 130 degrees and is about 40psi with 20W50 oil. I am pulling the engine to change the pan to one with scrapers and windage tray, check brg clearances, change as needed, and replace the oil pump. Do not intend to put high volume pump as boat is primarily used for pleasure. Since I will have the engine torn down to a short block, is there anything else I should be looking for?

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    Quote Originally Posted by fastmarlene View Post
    Great Forum Guys.
    My question, I have recently purchased a 20 1/2 Ft Carribean with a 540 engine. Do not have many of the build details as the previous owner did not do much engine work himself. Engine has hydraulic roller cam and roller rockers. Under hard acceleration from stop, the oil pressure will drop about 20 psi. It will come back when the boat is on plane and no longer accelerating. Once on plane if engine is held above 4500 Rpm for 3-5 minutes, the pressure will start to drop again. Reducing engine speed to 3500 Rpm or less will let the pressure come back up. The engine came with a box type Milodan pan. I am guessing the first pressure drop is caused by the oil being thrown to the back of the pan and the oil pump is sucking air. The second may be due to windage and or oil not draing back to the pan. Oil temp at this point has never exceeded 130 degrees and is about 40psi with 20W50 oil. I am pulling the engine to change the pan to one with scrapers and windage tray, check brg clearances, change as needed, and replace the oil pump. Do not intend to put high volume pump as boat is primarily used for pleasure. Since I will have the engine torn down to a short block, is there anything else I should be looking for?
    Too much oil in the pan. I'm guessing a 10 quart pan with probably ten quarts. Do a search on here. Lots of discussions about oil pans.

    With 10 quarts they are way too full. Try running 7 quarts and see if it improves before you yank the motor and pull the pan. BTW 7 quarts is plenty of oil for a BBC.
    Last edited by Boat 405; 12-14-2009 at 04:19 PM.
    Boat 405.

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    Quote Originally Posted by fastmarlene View Post
    Great Forum Guys.
    My question, I have recently purchased a 20 1/2 Ft Carribean with a 540 engine. Do not have many of the build details as the previous owner did not do much engine work himself. Engine has hydraulic roller cam and roller rockers. Under hard acceleration from stop, the oil pressure will drop about 20 psi. It will come back when the boat is on plane and no longer accelerating. Once on plane if engine is held above 4500 Rpm for 3-5 minutes, the pressure will start to drop again. Reducing engine speed to 3500 Rpm or less will let the pressure come back up. The engine came with a box type Milodan pan. I am guessing the first pressure drop is caused by the oil being thrown to the back of the pan and the oil pump is sucking air. The second may be due to windage and or oil not draing back to the pan. Oil temp at this point has never exceeded 130 degrees and is about 40psi with 20W50 oil. I am pulling the engine to change the pan to one with scrapers and windage tray, check brg clearances, change as needed, and replace the oil pump. Do not intend to put high volume pump as boat is primarily used for pleasure. Since I will have the engine torn down to a short block, is there anything else I should be looking for?
    I hope you meant 230*. 130* is impossible to believe, and if thats what your gauge says, check your gauge. Some of your troubles are caused by the Milodon pickup. The damn thing will make even the best pumps cavitate. It also seems to whip air into the oil more than most. Most of your pressure drop on long runs is caused by whipped oil. Like widiwmaker said, you can try lowering the oil level a quart and see if that helps. If this is strctly a pleasure deal, grap a B&B pan REX Marine. I am going to post up a few things soon that I learned about that pan over the Thanksgiving weekend. That pan really surprised me.



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    Quote Originally Posted by fastmarlene View Post
    Great Forum Guys.
    My question, I have recently purchased a 20 1/2 Ft Carribean with a 540 engine. Do not have many of the build details as the previous owner did not do much engine work himself. Engine has hydraulic roller cam and roller rockers. Under hard acceleration from stop, the oil pressure will drop about 20 psi. It will come back when the boat is on plane and no longer accelerating. Once on plane if engine is held above 4500 Rpm for 3-5 minutes, the pressure will start to drop again. Reducing engine speed to 3500 Rpm or less will let the pressure come back up. The engine came with a box type Milodan pan. I am guessing the first pressure drop is caused by the oil being thrown to the back of the pan and the oil pump is sucking air. The second may be due to windage and or oil not draing back to the pan. Oil temp at this point has never exceeded 130 degrees and is about 40psi with 20W50 oil. I am pulling the engine to change the pan to one with scrapers and windage tray, check brg clearances, change as needed, and replace the oil pump. Do not intend to put high volume pump as boat is primarily used for pleasure. Since I will have the engine torn down to a short block, is there anything else I should be looking for?
    Sounds just like my jet. I warm my oil up quite a bit more before I push it. I am also running the Milodon pickup. My engine must areate the oil cause it will drop to 45 after hard runs and 25 at idle then 2 minutes later it is back to 70?? I also learned on the dyno that that engine made 6 more HP with 8 quarts than it did with 9. I wish I would have tried it at 7. Next season I'm going to tig a different screen to the milidon tube.

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    I agree with GN7, 130* is way to cold for the oil to flow. I also would change the pickup, but for me that easy I always make my own pickups and pans. A stock chevy oil pickup is a better design than that Milodon. I was taught by the old guys is that if you need 50 weight oil you should be using an oil cooler. But remember that everybody has an opinion. Asks lot of questions then make up your own mind.
    Need help finding this 1973 Sanger 18'6" bubble deck mahogany bottom and stringers I was living in Pomona when I sold her in 1979. Just wonder if she still exists

    Update Found my old Sanger 12/7/14 in Reno.

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    If the oil is only getting to 130 and no oil cooler, your bearing clearances are suspect.

    Low oil temps and low oil pressure when running 20w-50. I'm hoping 40 psi is idle oil pressure. Maybe a little more information would be helpful.
    Boat 405.

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    I suspect that 130 temp is your water NOT oil. If your oil is only 130 it would be hard to whip it up and you surley wouldn't be hot enough to get rid of condensation! I would be willing to bet you are a qt or two too much oil.Your pickup needs attention your pan is crap but can work for your application with the proper windage tray I believe milidon makes a tray with a scraper you can buy at summit or maybe rex. Milidon pickups are junk but modified they work.JMO

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    X2 on that last response. I found the best way (cheapest) was to pull the
    pickup, get rid of the crappy designed "perforated plate" type screen, slip
    in a piece of stainless steel screen, and tig, or gas weld it back on the pickup box. and while the pump is off, slip one of those trim to fit baffles
    in between the pump and cap and be done.

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    Quote Originally Posted by jungledave View Post
    Sounds just like my jet. I warm my oil up quite a bit more before I push it. I am also running the Milodon pickup. My engine must areate the oil cause it will drop to 45 after hard runs and 25 at idle then 2 minutes later it is back to 70?? I also learned on the dyno that that engine made 6 more HP with 8 quarts than it did with 9. I wish I would have tried it at 7. Next season I'm going to tig a different screen to the milidon tube.
    Dave if that is the pan you are using from the boat when I sold it to you.

    We did notice a fall off on the dyno with that pan at WOT the oil pressure started to dive and not come back till you would let off. I never really kept into it more than 30 seconds at a time remembering that issue.

    We thought it might be the HV pump but it was a combination of the two

    That 540 ran with great oil psi numbers in my vette last summer using a Steffs 6qt oil pan and a standard volume pump.

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    One other thing to check is the pan bottom to pickup clearance ,,, 3/8" is what I strive for,,, and you dont want to be farther than 1/2" ,,, .......................Eric

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    Quote Originally Posted by Fonz69 View Post
    Dave if that is the pan you are using from the boat when I sold it to you.

    We did notice a fall off on the dyno with that pan at WOT the oil pressure started to dive and not come back till you would let off. I never really kept into it more than 30 seconds at a time remembering that issue.

    We thought it might be the HV pump but it was a combination of the two

    That 540 ran with great oil psi numbers in my vette last summer using a Steffs 6qt oil pan and a standard volume pump.
    Yea sme pan. I am convinced it is the pickup and not the pan. It did drop off on the dyno. I drained out 1 t0 1.5 quarts and the pressure stayed up along with a 6 hp gain. I ran the same HVHP melling select pump, same engine with a factory LS6 pan and tray with no problems oil pressure wise in my sleekcraft. I even ran it at 4900 to 5000 rpm for 20 miles with the old pan with no problems.

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    Default Newbie 540 BBC Oil Pressure Question

    Thank for all of the response.

    Water Temp, there was no thermostat on boat or valve in water line from pump. Installed valve to cut water back and that is when I got oil temp up to 130. Engine Temp was 110 running at speed. When oil pressure started to go down, figured no point to throttle cooling water any futher.

    Oil Temp, yes it is less then 130 degrees. Could not believe it myself. No temp guage but felt pan itself with my hand was just barely warm. Shot with infra red temp gun to be sure. Do not have oil cooler.

    Oil Pan, that is why I am pulling engine.

    Oil level, supposedly 8 qt. pan. Per earlier threads was going to experiment with with oil level but figured I would do that once pan is replaced.

    Brg Clearances, that is other reason for pulling engine.

    Pressue guage, put mechanical guage on engine where sender for electical guage was so think numbers are accurate. Sender was mounted on back of the block by distributer.

    Thanks for all of the input. Another set of eyes and ideas are always helpful.

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    If you are going to change the pan, I would seriouly look into the B&B pan. But you will make quite abit of improvement by just canning the Milodon or at the very least, rip off the perf plate and replace it with a screen. If yur oil is really 130* (which I find to be almost impossible if the thing has run for more than 15 minutes), that is way to cold and you are going to turn your oil to sludge in no time, and it isn't lubing worth a shit. You need to fix. Good Luck



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    Quote Originally Posted by fastmarlene View Post
    Oil Temp, yes it is less then 130 degrees. Could not believe it myself. No temp guage but felt pan itself with my hand was just barely warm. Shot with infra red temp gun to be sure. Do not have oil cooler.

    Oil Pan, that is why I am pulling engine.

    Oil level, supposedly 8 qt. pan. Per earlier threads was going to experiment with with oil level but figured I would do that once pan is replaced.

    Brg Clearances, that is other reason for pulling engine.

    Pressue guage, put mechanical guage on engine where sender for electical guage was so think numbers are accurate. Sender was mounted on back of the block by distributer.
    As the others have said, 130* oil temp is about a 1 mile idle, running a big oil cooler. Something is very wrong there. If that was correct, unless you have some huge clearances or a terrible oil pump, with the oil you are running, pressure should be very high.

    I am not familiar with the pan/pickup you are running. We run the stock Mercruiser/GM pan/pickup, with high volume Melling/Moroso pumps, and see a steady 60-70 psi at WOT with oil temps in the 200-230 range. and the pressure never varies. and this is running in the ocean from calm to 3 footers and more, so needless to say the oil is getting boounced around and not always wating to stay in the sump where its supposed to return to.

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