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Oil Temp Q for owners of both a 911 and 993 owners (cross post)

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Oil Temp Q for owners of both a 911 and 993 owners (cross post)

 
Old 01-12-2011, 06:10 PM
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Edward
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Default Oil Temp Q for owners of both a 911 and 993 owners (cross post)

On your 993, you know how the oil temp needle drops when the thermostat opens ...how you can see the needle actually dropping?
Why does my SC not do that? That oil temp guage moves along its path as the oil heats/cool, but no clear indication from the needle that the thermostat has opened from its closed (cold engine) position.

My SC btw is in great shape, and has been so now for many years, and no probs whatsoever. I am simply curious about this and have been so for years. Anyone got the answer?


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Old 01-12-2011, 06:23 PM
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Ed, when you drive, how long do you drive it? How do you know it is not stuck open?

I see the most dramatic temp needle drop on cool driving days in the Spring and Fall. Less so on hot summer days. No engine tray here.

I'm thinking stuck (open) thermo....or not getting it hot enough to open, and drop heat.
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Old 01-12-2011, 07:02 PM
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The thermo to the front coils opens shortly after start up on both, I bet its when the fan kicks on you see the difference (no fan on the SC).
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Old 01-12-2011, 07:24 PM
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Bill Verburg
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Originally Posted by Edward View Post
On your 993, you know how the oil temp needle drops when the thermostat opens ...how you can see the needle actually dropping?
Why does my SC not do that? That oil temp guage moves along its path as the oil heats/cool, but no clear indication from the needle that the thermostat has opened from its closed (cold engine) position.

My SC btw is in great shape, and has been so now for many years, and no probs whatsoever. I am simply curious about this and have been so for years. Anyone got the answer?


Edward
a 911 has 2 coolers and 2 t-stats. the engine mounted cooling circuit rises to temp then the front cooling circuit rises to temp. The temp curve if you observer carefully, goes up slowly, plateaus, goes up slowly then plateaus again.

on a 911 w/ a 3.6 t'p and only a front cooling setup will see the same sort of thing as a stock 964 up, small down, up, plateau. The small down is the long run of cool oil in the front lines mixing w/ and cooling the main supply temporarily. This isn't as noticeable in a 911 because of the inner engine mounted loop of cooling.
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Old 01-12-2011, 11:47 PM
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OK, now that makes sense! Thanks, Bill!

I never accounted for the difference in the engine-mounted oil cooler. How you describe the mov't of the needles is exactly how mine behave in both cars: 993 has that small drop down, then a plateau (more or less, of course); and the SC has no such drop but does behave exactly as you wrote. Now that you explain it, and the absence of that engine cooler in the 993, it makes perfect sense!

Still, I wonder if the T-stat on the 911s opens more gradually than the 964/993 T-stats ...do the latter units go "full open" from a fully closed position? I know in motorcycle oil coolers of years old (when I was deep into that decades ago), a simple bi-metallic strip was all that opened/closed the loop, so the addition of the finned cooling area was gradual. Dunno about how the 964/993 T-stat works, though. Any light to shed here?

FWIW to all, the SC is my track car, but does get streeted occasionally (to keep her exercised), so I know she gets plenty of heat, and the needle does rise in a timely manner on warmup, so I know it is not simply stuck open.

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Old 10-11-2018, 11:13 AM
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What's up with Carrera T prices? I'm finding great cars with 1000 miles or less and great specs for 10-15k off their msrp.
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Old 10-11-2018, 09:45 PM
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My guess is that the oil thermostat is largely unchanged from very early
like the oil pressure sensor
Porsche only changed things that needed it
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Old 12-21-2018, 10:54 AM
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sorry, wrong thread
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Old 02-03-2019, 10:45 PM
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Wrong thread

Last edited by I-Man; 02-04-2019 at 10:40 PM.
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