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Thread: Oil Pressure & Hard Morning Start

  1. #1

    Join Date

    United States

    1985 Mitsubishi Mighty Max


    Oil Pressure & Hard Morning Start

    Hey All,

    If anyone can shed some light into this problem I'm having that'd be greatly appreciated!

    I've got a 85 Mighty Max SPX 2.3 4D55 Turbo Diesel, when I start the truck in the morning
    it doesn't want to turn over. It takes several cranks before she wants to start up.

    My mechanic said the oil pressure wasn't high enough and has to build before the fuel pressure sends the
    fuel into the engine. Does this sound familiar to anyone? I had the turbo replaced about a year ago
    and bought the truck with a supposedly "completely rebuilt" motor.

    When I first got the truck it kicked over like a charm without any use of the glow plugs.

    Anyone have any ideas on what it might be?



  2. #2

    Join Date

    Burbank, CA

    1983 Mitsubishi Mighty Max

    He's full of crap. Couple things I would do........... Invest in a harbor freight compression tester for $35 for diesel. Has adapter to fit in glow plug hole. Should be MINIMUM 350 PSI each.

    When it's running how much pressure is at dip stick tube ? (Hold finger over tube and release)

    How much air comes from crankcase breather hose?

    Unless the vehicle is warm from sitting in the sun, all diesels need glow plugs to start.

    When was the fuel injection pump overhauled? YOU MUST USE DIESEL ADDITIVE with these mechanical pumps as our LOW SULFUR diesel has almost zero lubricity . You will not get alot of good life out of pump without it.

    Todays mechanics do not know squat about these trucks. Be prepared to tell them what you want if you are not mechanically inclined. Invest in a service manual (Ebay) only bother with the factory book as the rest are vague on the diesel section.

    Has anybody checked the injection pump timing?

    You have to question if the rebuild was done right or not. These 4d55's always either need to be bored for the next size piston (available in .020 and .040 oversize) or new sleeves and standard pistons installed. Most people seem to want to Mickey mouse it as they are too cheap to buy pistons.

    If you really want to know more about this engine you could get an actual OIL pressure gauge and plumb it in. I recommend on these oil and water as the factory gauges were worthless. Heat is key to these motors. They do not do well with any overheat condition.

    If you were in So cal I would be happy to give you a no charge evaluation


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