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Thread: oil pressure

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    Jedi Hopeful
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    oil pressure

    Engine rebuilt and almost ready to start, but not quite! I have read previous posts ( Healey forum) about the oil line and pressure, and have turned over the engine with no plugs, but get no reading on the OP gauge. Apparently there is no need to bleed it, and it has a new line. There was good pressure when I took it apart 20 years ago (!). I used appropriate assembly lubricant as I put it together, but cannot remember what it was. (Another (!))

    As far as I can tell the pump is engaged properly. The shaft dropped in quite distinctly.

    How long do I crank before the pressure should rise or am I missing something potentially drastic?
    Is it worth trying to fill the system through the OP line?

    Or do I worry too much?

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    Yoda CJD's Avatar
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    Re: oil pressure

    I would not worry about pressure at cranking speed. I usually spin the oil pump with a long screw driver before installing the distributor. Without the distributor the oil will not build pressure, but you can look in the hole and tell that it is flowing up and back into the crankcase. That is proof that all is primed and ready to pump. After that I just start the motor when it's ready. You should see oil pressure on the gage within 5 seconds after starting...or shut it down and figure out the problem. If you lubed the motor during assembly, 5 seconds will do no harm without pressure.
    John

    1955 TR2

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    Great Pumpkin TR3driver's Avatar
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    Re: oil pressure

    If you didn't pre-fill the oil filter, it can take a surprisingly long time to build oil pressure while cranking, even with the plugs out. The pump only moves a small amount of oil for every revolution, and runs at half engine rpm. Obviously it has to fill that entire canister before it can build any pressure.

    Some people do use a dummy shaft to turn the oil pump directly with a drill motor.

    But assuming you've used plenty of assembly lube, I don't think it hurts anything to just keep cranking until it comes up. With the plugs out, there is very little load on the bearings; and such low rpm means the lifters aren't working very hard either.

    You might try loosening an oil gallery plug, as a tell-tale for having oil pressure; just in case there happens to be something wrong with the gauge and/or it's connection. But I'd give it at least a couple of minutes before worrying about it.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: oil pressure

    Thank you both.
    I am reassured.
    The gauge was working OK when I put her away, but I could open the line and see if it squirts at me to make sure the connections are good at the pump and filter
    I will finish setting up the carbs and give it a serious whirl next week.

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    Yoda martx-5's Avatar
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    Re: oil pressure

    A friend of mine had a problem with the oil pressure reading on his 3B when he first went to start it after the restoration. As it turned out, he got too exuberant when using gasket sealer on the filter head and plugged up everything where the oil travels by the stud into the oil line. He had pressure, but it couldn't get to the gauge.
    Art
    '58 TR3A TS236xxL
    '92 Mazda Miata -- Supercharged
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    Re: oil pressure

    Just another little tip I learned from ruining fresh rebuilds over the years...

    I never spin a new engine with a starter until I am actually starting it. If you lubed all the bearings and cylinders, then spinning it without oil pressure won't necessarily hurt it, but it also doesn't do it any good. The parts that take the most stress from free spinning is the cam and lifters. Spinning scrapes the oil off the cam, and it will not be replaced until the engine comes up to speed and slings more oil to it off the crankshaft.

    Granted...I have had several rebuilds that did not start immediately, for one reason or another, so it does happen. But if I have a starting issue and it doesn't start within a reasonable time, I pull the valve covers and pour more oil down and around the cam...so down the pushrod tubes on the TR engine. If I want to check oil pressure and gallery integrity, then I do it by pulling the dizzy and spinning the oil pump shaft without turning the engine. For Fords and Chevy's I have taken junk distributors and cut the tops off so the oil gallery can actually build pressure (every engine I know of requires the distributor to be in place to build pressure). I have wanted to do the same for my TR engines, but I have not rebuilt enough to get serious about it. For my TR's I just spin the pump until I SEE the oil moving, and then seal it back up and start it.

    Like Randall mentioned...always fill the oil filter as high as possible, not just for initial rebuild starts, but also on oil changes. The goal is to minimize any time spinning the engine without oil pressure.
    John

    1955 TR2

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    Yoda Geo Hahn's Avatar
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    Re: oil pressure

    Quote Originally Posted by TR3driver View Post
    ...it can take a surprisingly long time to build oil pressure while cranking, even with the plugs out...
    I distinctly recall one of the longest minutes of my life waiting for the gauge to move (it finally did).

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