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Moss Motors, Ltd » Austin Healey 100, 3000 » Mechanical » zero oil pressure etc.

zero oil pressure etc.

Last post 06-01-2008, 3:34 PM by motorbill66. 1 replies.
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  •  06-01-2008, 2:50 PM 14702

    zero oil pressure etc.

    I have a 1958 Austin Healey 100-6, BN6. The problems are -- When the clutch is depressed the engine slows down about 200rpm, engine noise and zero oil pressure.

    I have found the following:

    1. When engine was cranked could not detect oil coming out in the rocker area or out of the oil feed pipe (when disconnected). However, when air pressure was introduced at the oil filter (filter removed) residual oil at the rockers could be seen moving.

    2. The crankshaft is shifting slightly (end-float)

    3. A feeler gauge shows that end-float is .016” (checked from beneath engine with oil sump removed)

    (specs say .0025 to .0055”)

    4. The no. 3 cylinder connecting rod is dry while the rest of the internal engine is covered with oil

    5. The oil pump is putting out 45psi as read with a pressure gauge where the oil comes out of the engine and into the oil filter (spin on oil filter removed)

    6. Each connecting rod big end will shift slightly side to side leaving a space of about .010“.

    7. The oil pressure gauge on the dash is functional.

    8. The oil line from the engine to the gauge is clear.

    Why no oil pressure? What’s causing the engine slowdown when clutch is depressed? Future plan of attack?

  •  06-01-2008, 3:34 PM 14703 in reply to 14702

    Re: zero oil pressure etc.

    It seems you have so many places where oil pressure is not being contained by the components involved that even if the pump itself is functioning well, it can't push enough volume to keep up. The RPM is dropping most likely because the thrust bearing babbit is gone and the friction at the thrust face is increased. If this continues, the connecting rods will(and may already have) run out of longitudinal clearance, whereupon the pistons will tilt in the bores due to bending forces on the rods. Sounds awful, huh? Additionally, you may have spun a bearing, or at least destroyed it, on connecting rod number three's big end. Have you pulled down the connecting rod bearing caps for inspection yet?

    Future plan of attack? Yank it out and overhaul it thoroughly. Don't run it any more. You you could hurt something very expensive to replace.

    Motorbill
    From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon