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- Newsgroups: rec.autos.tech
- Path: sparky!uunet!spool.mu.edu!agate!dog.ee.lbl.gov!news!nosc!halibut.nosc.mil!koziarz
- From: koziarz@halibut.nosc.mil (Walter A. Koziarz)
- Subject: Re: Oil pressure question?
- Message-ID: <1992Dec17.141506.15531@nosc.mil>
- Sender: usenet@nosc.mil (Network News)
- Organization: Naval Ocean Systems Center, San Diego
- References: <1992Dec15.203102.24544@ncar.ucar.edu> <1992Dec15.154701.1@bronco.fnal.gov>
- Date: Thu, 17 Dec 1992 14:15:06 GMT
- Lines: 23
-
- In article <1992Dec15.154701.1@bronco.fnal.gov> colombo@bronco.fnal.gov writes:
- >In article <1992Dec15.203102.24544@ncar.ucar.edu>, cbh@windsurf.scd.ucar.edu (Cris Hannu) writes:
-
- >> I've got a question about the relationship of oil pressure to volume.
- >> I've got an '84 Bronco II w/ 2.8L. I had the engine rebuilt (it has now
- >> got about 10,000 miles on it), it was bored out and I had a new cam put in.
- >> Anyway, the oil pressure is higher now (than originally) and it seems to
- >> *increase* when the oil starts getting low. Is this normal, or do I have a
- >> flaky sending unit? I would've thought it would *decrease*.
-
- >Oil pressure is not related to the volume, unless you run out. :-)
-
- Well, not *exactly* true... only to a first approximation... When volume is
- reduced there is less oil available to dissipate the heat removed from the
- power components ('bottom-end' - crank, rod bearings, etc...). The oil present
- *will* become hotter (since there's less of it, it will dissipate heat to the
- atmosphere less effectively (that's *why* a sump holds so much, anyway...)) and
- will 'thin-out' and pressure most assuredly will drop. This effect only
- becomes important under load... at idle there isn't much (comparatively) heat
- to remove and dissipate from the power components.
-
- Walt K.
-
-