Cranking Oil Pressure

PaulW_NJ · Aug 9, 2013

I'm finally getting to starting up the C123 motor in my 240U that I rebuilt. Block was tanked clean, new sleeves, pistons, etc. Rocker arm was disassembled, and rodded out and cleaned. So passages should be clean. Oil pump looked fine: I sanded flat the bottom plate & replaced gasket. Oh yeah, I almost forgot: I replaced all rod and main bearings too.

I want to be sure the oil circulation is OK before firing it up. Cranking it (without starting it), I'm not seeing any appreciable oil up on the rocker arm. Which is my concern. Is that normal? I opened the oil pressure gauge port, and oil flows from there when cranking. I connected an accurate gauge to the port, and it goes up to 10 psi when cranking. So I assume it's priming OK. I read it's supposed to go to 45 psi when it's actually running. . . so far I'm only cranking it.

This is my first major rebuild, so don't know if what I'm seeing is a problem, or not. Appreciate your advice.

Nebraska Cowman · Aug 9, 2013

If you oiled everything as you put it back together i wouldn't worry about it.

CNKS · Aug 9, 2013

Start the engine with the valve cover off, be sure you have pressure, it may take a few seconds, then look at the rocker arms. If no oil then something is plugged. I think the oil goes up thru a hole in the middle rocker arm support.

pete 23 · Aug 9, 2013

I would start it and watch for oil at rockers. It won"t hurt a bit to run without any top oil for several minutes. Perfect circle used to recommend blocking the oil flow to head when checking for oil consumption through the valve guides and run it several miles to check it out. If you do not get oil, suspect the center stud for rocker arm shaft as it has a hole drilled part way through and then out the side of stud so if you put in upside down or substitute a different stud you will have no oil to rockers.

Ron W · Aug 9, 2013

If you are really worried, remove the spark plugs, and have someone pull start (without actually starting the engine) you until you have oil pressure. Check it all out. Then put the plugs back in and go for it!

gene bender · Aug 10, 2013

You sure did lube all the bearings and pistons when you installed them correct. Just start the engine and quit fretting. Oilwill get to the rocker arms quickly providing you didnt get the stud in wrong. Ive been rebuilding those engines for 40 yrs and never had any problems yet starting with oil pressure. Those arent racing engines

PaulW_NJ · Aug 10, 2013

Thanks for all of the helpful responses. I"ll finish getting the rest together, and get it started, and then keep an eye on the rocker shaft. I did lube everything up down below the head, but I"ll pour a little oil onto the rocker until it runs.

mkirsch · Aug 10, 2013

I've never seen these old engines develop any appreciable oil pressure until at least a few seconds after they start.

Cranking Oil Pressure

PaulW_NJ

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Nebraska Cowman

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CNKS

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pete 23

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Ron W

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gene bender

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PaulW_NJ

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mkirsch

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