temp readings on the 101 freeway

[dferlauto]

I have been doing frequent runs from the S.F. Bay Area to Santa Barbara. My '69 912 is a real trooper... always runs flawlessly. 30 MPG & 2/3 cup of oil for the 600 mi round trip. There is certainly something comforting about that little 4 banger at my back !
I usually run between 3500 & 4000 rpms. At 3500, the temp gague runs straight up in the white area...at 4000 rpms it starts to creep up... about 4 or 5 degrees over vertical. Mountains add some extra heat, but the car eventually recuperates. She will run all day at 4000 rpms with the gague just off of vertical. I have recently changed to Mobil 1 with no real effect on temps. These temps seem to be consistent whether it is a 90 plus degree summers day or last weekend with some snappy winter weather.How does this jive with your experiences? I guess I should be grateful that it appears to hold up ok in the heat, but can't help wondering about that temp gague. The car has run flawlesssly for 2 years now.
I have heard of a calibrated temp gague that fits into the clock opening in the dash. We all know how usefull those clocks are...does anyone have a source for this item ? Any other recommendations ( short of an oil cooler)? I bought this car to resist the temptation to buy a Buick when I retire & want to keep her in good shape !
Thanks for any feedback.
David
Mtn View, CA
1969 912
2000 Beck Porsche

[pjv911]

MAYBE THE OIL COOLER ON THE MOTOR IS BLOCKED WITH FILTH.

[wastintime]

I really wouldn't worry about the engine temperature, and I don't think you need to have another temperature gauge if yours is working. You can look at the sender to make sure that it is intact, but the air cooled 4cyl is one of the hottest running engines that there is outside of an airplane. The ambient air temperature really isn't going to make a difference as far as the temperature of the engine is concerned once it's running and warmed up. 90 degrees might as well be 30 degrees to that engine. It's basically summer all year long here in SC and I don't think I've ever gotten the temperature on my engine to go more than a few degrees past vertical like you described.

Andrew

[WFBowen]

David: I certainly know where you're coming from - my first 911 (a 69 S) would jump to about 3/4 up the gauge when running hard in hot weather. A 356 super also did this (when they had just opened I-5). The reason Porsche never used the numerically calibrated gauge on its US cars is that Americans weren't used to seeing those high numbers.
For peace of mind, just make sure your timing is not over-advancing at revs & your motor is clean, etc. What I finally did to sleep at night was to drive the car hard at 4K for a good stretch, coast to the side of the road and check the plugs. This is really the key test of mixture & proper timing.
Also, I've had 9 various Porsches over the years and do feel that ambient air temperature plays a noticeable part in the gauge reading but that's just my seat of the pants opinion. I do know that my 912E (which had no oil thermostat function) would reach a point where the gauge would keep creeping into nail-biting territory, but never hit the red.

[COLDBASS]

Originally posted by WFBowen
David: I certainly know where you're coming from - my first 911 (a 69 S) would jump to about 3/4 up the gauge when running hard in hot weather. A 356 super also did this (when they had just opened I-5). The reason Porsche never used the numerically calibrated gauge on its US cars is that Americans weren't used to seeing those high numbers.
For peace of mind, just make sure your timing is not over-advancing at revs & your motor is clean, etc. What I finally did to sleep at night was to drive the car hard at 4K for a good stretch, coast to the side of the road and check the plugs. This is really the key test of mixture & proper timing.
Also, I've had 9 various Porsches over the years and do feel that ambient air temperature plays a noticeable part in the gauge reading but that's just my seat of the pants opinion. I do know that my 912E (which had no oil thermostat function) would reach a point where the gauge would keep creeping into nail-biting territory, but never hit the red.

I too have experienced the 3/4 mark on the temp gauge. The one and only time that this occurred was during mid-late Sept. I was driving to a friend's house in San Dimas (90+ degree weather) with my A/C on and the engine at a steady 4000 rpm...the oil light flickered (oil level was fine) as I pulled up to the driveway. I turned the A/C off on the way back home and noticed that my 912E was slightly missing at high rpm. After my engine was pulled (40k since prevous owners rebuild), we (tuner and I) later discovered that I dropped a valve seat on number 3. As everyone knows, with the engine out , one thing leads to another, the camshaft was flat, and the case appeared damaged at the seam. 2 months later, new case, new FAT camshaft, 96mm JE P/Cs, bigger valves, porting & polishing, shrouds being powder coated, etc...should be complete by end of Jan. For engine cooling, I do plan on adding a MOCAL external oil cooler w/electric fan and switching from a YORK a/c compressor to a rotary style unit. Additionally, a numerical oil temp gauge will be added. All this downtime has delayed my participation in the 912 owners gatherings (assuming they allow 76ers). Hopefully, 2002 will be a better year for everyone...

Bob

[Green 912]

Ambient air temps have a direct relationship to motor and motor oil temps. Pjv 911 hit a good point on the head. If you haven’t cleaned the oil cooler in recent memory it is likely to be at least partially blocked. Oil mist and everything that the car sucks into itself with the cooling air combines and clings to the oil cooler. You might not have a cooling "problem" but when you consider that the best oil temp, in regards to wear and fuel efficiency is 180 deg, the closer to 180 the better. It isn’t hard to change the ambiguous temp gauge and sender with the unit that reads in deg thus alleviating some likely unneeded worry.

I use the internal cooler and an added Mocal 19 row cooler fender mounted in a forced air box, with a 180 deg thermostat. Even on the track in 90 + deg ambient air temps I haven’t seen higher than 190 deg. If I had to replace the cooler I might go to a smaller 13 row cooler as the 19 is, I think, too much. At times I block it off and still sometimes have a hard time getting the temps up to min operating values.