Oil oil pumps are positive displacement types, so the faster the engine spins the more oil/sec gets pumped. The journals and bearing "wedges" don't get any bigger, so pressure must go up. At less than frisky RPMs the pressure relief valve will start to modulate, which is why our oil pressure goes up with lower engine revs, but then levels off and stays the same throughout the rest of the RPM range.
Your problem doesn't seem too bad though. I think the 20w had much to do with the higher pressure at idle, but your relief valve should keep your pressure within safe limits over that.
Good luck!
Jim M
--Previous Message--
: The pressure relief valve controls the
: oil pressure. The filter bypass valve
: is in the filter, and it opens if the
: filter gets restricted.
: Glen
:
: --Previous Message--
:
:
: --Previous Message--
: That's a good question, and I'll offer
: my
: thoughts on it, keeping in mind that I
: ain't that bright to begin with, and
: usually think "more is
: better"...
: The oil pressure is required mainly to
: be capable of supporting the "oil
: wedge" wrapped around the
: journals, and providing lube oil for
: all else. The injuneers have determined
: how much pressure is required to do
: this, and have established basic
: parameters. I look at any more pressure
: than is necessary as being a waste of
: power and adding heat.
: What's the magic number? I don't like
: to see more than 75-80 lbs. Does it
: really hurt to have more? I doubt it
: until it gets to the point of rupturing
: hoses and filter cans!
: On the other end of the scale is
: minimum pressure. An engine can run at
: idle no-load with just a handful of lbs
: of oil pressures, but as soon as it
: gets a load it needs enough to support
: the oil wedge. Whenever I find myself
: lugging my old Land Rover in 3rd gear,
: I usually just side-step the clutch to
: get the revs up a bit for my oil
: pressure, vs going through the chaos of
: getting it back down in 2nd at anything
: over a crawl...
: Glen
:
: --Previous Message--
: Hi.
: O.K. so how much is too much and
: why???
: My 2002 Buick LeSabre has 125 PSI at
: speed and the car has over 220,000
: miles on it. Back when we were racing
: a TR250 the car was dry sumped and it
: had a constant 100 PSI oil pressure.
: After three races the engine came apart
: and there was absolutely no wear on any
: bearings... Take a look at your little
: Jap car sometime when it's running if
: you dare open up the filler cap... It
: will blast you with oil like crazy..
: Really is too much pressure even
: possible?
: P.J.
:
:
:Thanks everyone for tour thoughts. I
: have not checked the relief valve
: because the shop manual sais that it
: only was there in case the filter got
: plugged. I will check it today.
:
:
:
:
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