Hello to all! In addition to performing homage to those on this list who so
willingly share their vast knowledge with others (like me :-)) I have a Q
regarding my TR6. I was wondering if anyone would like to take a stab at it.
SYMPTOM: Whenever I change oil/filter in my '6, I get oil pressures of around
80-85PSI hwy / 50-55PSI idle. Excellent so far! Then, this happens.
At some point, typically on a hot day, I'll get stuck in traffic or
end up in stop-and-go. Then, after maybe twenty minutes of this (oh,
my temp. indicates right around 1/3 of the gauge at this point) I'll
go back up to hwy speeds, and note that my oil pressure has dropped to
around 50PSI at hwy. Then, when I slow once more, pressure drops to
between 20-30PSI. Afterwards, temp reads around the 1/2 mark. Plus,
these readings then become typical except for immediately after
start, when they're a bit better.
So, here's what I've tried so far:
1) Oil change/filter change- problem reoccurs as indicated above.
2) Checked voltage stabilizer and instruments (I was having a problem where
turning the headlights on resulted in a higher temp; it was a problem with
the headlight circuit) ...no problems.
3) Checked for oil leaks- Nope, I had the engine redone (block painted) a few
months ago, and I'd still spankin' clean; plus, the oil in the engine
remains clear golden-brown. No particulates/black stuff in evidence.
So, what might this be, and what should I check next? My tyro diagnoses so far:
a) Oil pump going bad? This doesn't explain the 'OK then sudden turn for the
worse that's semi-permanent.' Or does it?
b) Viscosity breakdown in the oil? I dunno. Why would it do this? too hot?
c) bad oil...I've used both 20W50 and 10W40 (my garage switched it last time,
after thinking about it) with new filters each time. Same problem.
d) Oil pressure relief valve 'releasing' at the 90+PSI readings on the hwy and
then 'sticking' open a little?
...anyhow, I'm loath to tear the car down now, as I'm hoping to drive from MA
to CA in a couple of weeks...the readings aren't out of line, and it's been
happening for some time, so I'm not too worried about it (except maybe Nevada)
but I kept thinking 'oh, bad filter/whatever' whenever it worked after an oil
change. It's gettin' annoying, though. So, any wisdom appreciated...and if
any listers are in Cambridge MA through through 6/7, or in/near Santa Monica
this summer, I'd be pleased to buy a round.
Cheers!
...oh, and for those that haven't...check out the TR6 page at:
http://www.mit.edu/people/zimerman/tr6.html
...thanks.
-J.B. Zimmerman
'70 TR6 CC58880L 'Amanda'
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Jacob ben-David Zimmerman can be found at: zimerman@mit.edu
http://uss-repulse.starfleet.com/home.html MIT/DACS
Faster, faster, faster, until the Thrill of Speed Overcomes the
Fear of Death. -Trent The Uncatchable/SEO
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