----> If the flow remains the same, but the pressure drops, this is because
the thinner oil is leaking past the bearing surfaces faster. The oil
pressure is monitored at the main distribution oil gallery. From there, it
takes a long circuitous route through the bearings, oil transfer holes
drilled throughout the crankshaft and block over to the cam bearings and up
to the rocker arms, and finally seeps out at each bearing surface and
returns to the sump via gravity. So, if you are measuring low pressure at
the main gallery, and each bearing is weeping more oil, and the pressure
drops to subsequent bearing surfaces further down the oil circuit until at
worst case, the pressure reaches zero before reaching the furthest bearing
and you can guess what happens next.
Richard
At 03:53 PM 10/23/99 -0400, you wrote:
>I guess the other side of this is, what is necessarily wrong with using
>lower weight oil, even if pressure drops, if the flow remains that same.
>That is, the bearings would still be lubricated, right?
>
>---
>On 10/23/99, Andy Webster wrote:
>>The oil pump provides flow...not pressure.
>>Pressure is provided by the resistance to the shearing forces applied as oil
>>is forced through small spaces, such as between bearing surfaces, through
>>filter media and down small galleries. So as bearings wear and the spaces
>>get bigger the oil flows through with less restraint,like sucking your
>>thickshake (or partially gelatinated non-dairy gum based beverage) through a
>>wider straw.
>>So really thick oil is bad news for a tight tolerance (new) engine and
>>really thin oil wont build any pressure in an old worn one.
>>Andy
>
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