Quote:
Originally Posted by chipj29
I was always under the impression that when oil pumps fail, they fail "open", so there is no stoppage of oil flow to the motor. It results in extra oil, and extra smoke.
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I have never taken one apart, so I don't know for sure.
Here's what I do know:
If the oil has to be pumped in, that means it's not under pressure and is relying on the pump to move the oil.
The pump has a piston that moves up and down and is powered by intake air pulses. The speed that it moves up and down is solely dependent on the engine speed. It cannot run too fast.
With a reciprocating pump, there has to be a pair of valves that: let oil in to the pump from the reservoir on the down stroke, and prevent oil from going back to the reservoir on the upstroke (valve 1) and let oil out toward the fuel on the upstroke, and prevent fuel/oil from coming back into the pump on the downstroke (valve 2). If either valve fails, the engine will get less oil.
The pump can vary the oil mixture ratio. This is a mechanism that I don't understand (and the picture is no help...). I can see where a failure here could indeed let too much oil into the engine.