lowered my oil temps 35 degrees

niner11 · 07-04-2004, 02:40 PM

My stock SC had been showing oil temps as high as 250 f after sitting in traffic with ambient temps in the 85 to 90 f area. The car has the factory "trombone" loop and before buying a carrera or mocal cooler, I wanted to know if the car had a cooling problem that I would just be masking with a little more cooling efficiency.

Installing a numerical oil temp gauge and the correct sender was probably the easiest (and most cost effective) way to tell exactly how hot the car was really running. Well after installing the new gauge combo, the difference in temps is about 35 f cooler. Not entirely sure why the old temp gauge was so inaccurate. I'm guessing that when the white gauge faces were installed (PO) the needle position was put on in the wrong position.
Long story short, the car will not get any hotter than 210 or 215 in hot Atlanta driving. If anyone else has oil temps on the warm or hot side I'd recommend a new gauge combo before spending a thousand dollars on additional cooling. Also, this is my first summer with the car so I'm wondering if these temps are normal.

niner11 · 07-04-2004, 03:03 PM

Thats a good idea but if you are a sherpa then water boils at a much lower temperature. Using the old gauge I would have to reset the needle pointer a few times until 212f was correct on the indicated temp. Didn't think about boiling water, thanks.

rdane · rdane's Garage

If it were my SC I would be doing some more checking since 225/50 in bad traffic on a 90 degree day here is not uncommon, no matter what oil cooler you have.

Joe Bob · Joe Bob's Garage

OEM Dash gauges are not the most accurate....I always check them with a hand held pyrometer....manufacturers cut costs with cheap gauges.

Doug Steinel · Doug Steinel's Garage

Why do you think the second gauge with the lower reading is the accurate one? I have an SC engine with a trombone and when it is 90 degrees and traffice is stop and go after 10 miles on the highway the temp climbs above 250. I think your first reading was accurate.

niner11 · 07-04-2004, 09:03 PM

Doug, I think that the first gauge was wrong because when I turn on the key it points pretty close to 120f. The second reading was from a new sender and gauge combo that did not have the pointer needle removed and re-attached. Like I said the PO had the thing apart to install white faces. When ever the needle is removed the gauge is only as accurate as the mechanic that puts it back together. I have used a digital probe at various points in the system and it is consistent with the temp reading that I'm seeing from the new gauge.

Another point is that the motor has 2000 miles on it since a rebuild. I'm told that they run a lot cooler when everything has been cleaned up. Who knows.
If you are seeing 250f or more I would look for a problem or find a carrera oil cooler. I think that most everyone agrees that is too hot for long term use.

rdane · rdane's Garage

"My stock SC had been showing oil temps as high as 250 f after sitting in traffic with ambient temps in the 85 to 90 f area. The car has the factory "trombone" loop"

Those conditions and with that cooler, 250 is common. I wouldn't trust the new gauge reading if you want to keep your new engine in one piece. For that kind of driving you need a Carrera cooler with a good fan.

niner11 · 07-04-2004, 09:40 PM

rdane, with a good mocal or carrera cooler and a fan would 185 f be a possibility. Like I said this is my first summer with the car and I didnt know what to expect in Atlanta traffic. One thing is for sure, I will not let a new motor get that hot very often. The digital temp prob has never seen temps in the oil tank higher than 230f regardless of what either of the stock gauges read.

Since there is some discussion as to what the temps really are I will drill a hole in one of the extra caps that I have and thread it into one of the timing chain covers. It was an extra cap that came from the carrera tensioner update kit. should put this whole thing to rest.

Grady had an idea to put temp probes at several different locations and measure the temp drop at the engine and loop.

rdane · rdane's Garage

Niner,
My trombone seldom hit 250 outside the track. But I seldom drove in traffic and hot days are rare here. The one day on I5 in bumper to bumper I have done, temps hit 230/250 way faster than I ever thought possible. And I have new gauges.

Which is why I would be very cautious with that set up. My take is 225/250 is all too common in bad traffic and any kind of warm (90+) outside temps.

I have since added a big B/B in the front bumper. Car seldom hit 180 even on hard runs as a 3.0 or now as a 3.4. I often wonder if I added too much cooling. But bumper to bumper traffic on a warm day would send the 3.0 to 200+ in just a few minutes with the B&B cooler and no fan. No fan is not a good set up for a car that will ever have to sit in traffic.

I suspect a Carrera cooler with a good fan would easily keep the oil down to less than 200 the majority of time, even in Atlanta.
Someone from Atlanta here must be able to tell us if that is true.

Jack's BBII runs two Carrera's with fans on his 3.6 I think. Good reference for what they can do.

But I also think Noah has the right idea, get everything good and clean and keep the air flowing. Problem with temp readings is the worse time for the engine is the hardest time for you to measure accurately I suspect.

sturco · 07-05-2004, 02:01 AM

FYI- I had my gages re-done with faces etc. by a CA much touted rebuilder. I could not figure out why the car was overheating when it never did before, (2.2S). I changed the sender, tried everything and sent the gage back to CA. They could not find anything wrong and it got quite ugly between us until they discovered they had silk screened on the wrong scale for the gage. After they corrected their mistake it has run fine. As for your 250 degrees... I run in my track car (3.2 early 911),an SC oil cooler system.The front cooler is a small 9" X 5" unit vs. the trombone cooler. The side lines are exposed (71 911T rockers) which I feel are the heart of keeping this car cool as the front unit is so small. It keeps the car at 215 on the track in 80 degree weather. Steve

Ray B · 07-05-2004, 05:03 AM

Niner, Welcome to the ATL. Good bunch of folks here. Look on the Peachstate PCA website for upcoming events (auto-x July 25th). Also the pelicans have some informal "runs" from time to time. Post or PM if you want any advice on local mechs- many good ones, some others (Reggie at Proformance in Marietta

). Cheers. Ray

niner11 · 07-05-2004, 12:34 PM

Ray, thanks for the info. Seems like most of the Porsche shops are north of the perimeter. I have done a bunch of work myself (other than the engine rebuild

) but would surely appreciate info on a good local Porsche shop. Thanks, Chuck

sc · 07-05-2004, 02:11 PM

Niner,

I lived in Northern CA. last year and my stock 79 sc saw 230-240 all the time in traffic- with a loop cooler. I now live in Phoenix and have upgraded to a carrera cooler and a Zirgo 8" (http://www.zirgo.com/detail.lasso?itemid=ZF8) 1000 cfm fan. The temps on a 105+ degree day never go over 210!