Operating temperature
 

Hi Guys I have a 73t with carburetors and a 2.4 just wondering if a running temperature of 90c is normal with ambient temperatures of 72 degrees Fahrenheit.
Thanks
Mike

May not be apples to apples Mike but my 3.2 runs around 210 dF when driving around. Will climb from there when sitting idle for an extended period. When this happens, I turn ON fans that blow through a front fender Mocal. Temps drop back to 210.

Thanks Karl, was out for first drive of the season yesterday and it just seamed a little higher on my gauge then I remember but it’s only 194f so I guess it’s within normal range.

I also had some mouse droppings blow out of my heater vents which also caused some concern. Been checking everywhere but no signs of nesting anywhere so far.

Here's a users manual for the '72 911S in German:
http://content.us.porsche-clubs.porsche.com/PorscheClubs/klassieke-porsche-911-en-912-club/files/BetriebsanleitungTyp911S1972_V2_Optimized.pdf
It says that oil level has to measured at operating temp of at least 80°C as defined as warmed up engine. And it tells that the oil temperature must not be higher than 130°C. Otherwise slow down, check the oil level and go to a workshop to clarify the issue. Normal operating temp on an aircooled 911 is 80-100°C depending on ambient temperatures and driving conditions. Higher temperatures are not common on normal cruising.
Oil temp varies depending on driving conditions. On idle at hot summer days in heavy traffic it might climb up to 100°C and
even a bit higher but it should fell to normal temps immediately when driving again. If it drops less than 80°C on a non winter day check the oil thermostat in the rear right wheel housing.

Thomas

Thanks Thomas that’s a lot of good information, really appreciated.

Mike

Welcome :-)
Here's another users manual for a 1969/70 2,2s model:
http://content.us.porsche-clubs.porsche.com/PorscheClubs/klassieke-porsche-911-en-912-club/files/Porsche911T1969_1970USownersmanual.pdf

Per Steve Weiner (https://forums.pelicanparts.com/porsche-911-technical-forum/615480-operating-temperature-question.html#post6095216):

Good link, thanks

My '70 with carbed 3.0 runs at a steady 185 maybe 190 if it's really warm out. Trombone cooler.
My 3.2 temps are like Discseven has.

90 c = 194 f

There, save everyone the trouble of looking it up.

Seems fine. What oil are you running ?

Das sind Porsche, wir denken nur in metrischen Maßen

Concerning engine oils and ambient temperatures refer to this information of the user manual of aircooled 911's:

https://i.imgur.com/1jtIRZo.jpeg

Thomas

I have always found it interesting that back in the day Porsche was ok with a 40w straight weight oil of the hottest temps, and a "fuel efficient" multi weight 10-40 for hot temps. Interestingly they also show a 20-50 for the hottest temps in multi-grade, and 10-50 for lower temps than a 15-50 or 20-50. So which is it? Can a 10-40 handle the high ambient temps and potentially lower oil temps as its thinner oil, and we know thicker oil raises oil temps? If we can run a 40w straight at hot ambient temps why not a modern 10-40? As for the 15-50 vs 20-50....I thought the lower number was for the color end of the ambient temp range and had no effect on the top end? I'm so confused! LOL

Here in Florida it's in the 90's all summer and humid, in the winter we don't see freezing. The means a 10-50could be perfect. Porsche air cooled oil is 10-60, which doesn't even show in those old manuals. My 3.6 runs cool, my 3.2 always runs warm. I have often thought of swapping down in weight to see if it help s any in the 3.2. We also need to remember that that chart is from an 80's manual, and the other manuals posted are from the early 70's. oil has changed a lot in that time (good and bad).

I'm certainly not an expert like most on this forum. My car is a 77 S. Leaks oil due to the case and other issues.

That said......What I can tell you is when my gauge starts "creeping" up......I know it's time to add some oil. I add it and it's perfect until the next time.

First of all - I don't want to hijack this thread as an oil thread again....there are plenty of threads here about oils. I recommend to read on there.


@Duc Hunter
https://vpracingfuels.com/tech-talk-insider-articles/oil-viscosity-explained/

You're right - these tables dated from the 70ies and 80ies. Modern oils can perform better than older ones.

Which oil you use in your car is result of several decisions: Personal preference, price, availability, others experiences and many more.

All I can say:
* The higher the ambient temps and the higher the heat stress on the engine are, the "thicker" the oil should be on high temps.
* I ran a high sophisticated all synthetic 10W60 (no brand known to me) from the workshop I got the car for the very first service. Result: Engine leaked that much that oil dropped on the heat exchangers and I thought the car will burn down now while driving it the first time on the autobahn and I smelled the oil fumes and seeing steam in back mirrors... Oil pressure not bad, but not as good as I wanted to see on idle and climbed up to barely 3bars max on hot wheather.
Switched to a petroleum based / non synthetic 20W50 (Liqui Moly Touring High tech). Result: Almost no dripping any more, reasonable higher oil pressure cold and warm.
Reasons: The petroleum based / non synthetic oils let the rubber sealings swell again by nature. Synthetic oils (no matter if full synthetic or not) doesn't. Why? It's because of their ester based oils. They don't let swell the sealings. Therefore they need additional ingredients to let the seals swell again. And that's the problem: Mostly modern oils have these ingredients, but not enough for aircooled engines like our beloved Porsche engines. Further reading e.g. https://www.lube-media.com/wp-content/uploads/Lube-Tech-138-Sealing-compatibility-of-ester-base-oils.pdf
* Too less oil in the circuit let increase the engine oil temperature
* Make sure that the oil coolers are free of dust and not blocked
* Make sure that the thermostats open as designed
* Make sure that your ignition timing and advance&retard works as designed and being adjusted as Porsche recommended
* Make sure that the mixture is in spec as well, check it on a certified gas tester or at least with a lambda gauge both idle and cruising with AFR ~14,7, WOT & accelerating with AFR 12,5.
If all this been done, you're engine should run not much hotter than ~100°C / ~212°F on common street use. Racing / track day is another story of course.
Keep in mind that these oldfashioned aircooled Porsche were designed to be operated with the oils available of that time. I won't use either a 0W or 5W on an aircooled 911. At least 10W as Porsche originally specified above. As you guys mostly live in the US which is mostly warmer/hotter than e.g. Europe I recommend to go with at least a 15W40, 15W50, 20W50 or similar...But again: It's up to you.
And don't forget: These engines are 30 or 40 years old now and many of them still haven't been overhauled since. And most engine have far more higher mileage than most of odometers will tell...The higher the mileage of an engine is, the thicker the oil should be...this is valid for all engines, not only Porsches. And yes - it's true - a fresh overhauled engine is tight - with any oil! Question is how long this will last...

Finally and the very last task on the list to cool down an aircooled 911 - and only if all above tasks have been worked - you can install the 90110536102 intermediate pieces with reduced diameter. We had a discussion about them not long ago. I can confirm that these will bring up your oilpressure even on idle and cool down the engine in all operating conditions by at least 10-20°C / 20-30°F:
https://forums.pelicanparts.com/porsche-911-technical-forum/1141941-too-low-oil-pressure.html

Thomas

This thread is turning out to be an interesting read.

Pmax. Im running Valvoline VR1 20w50 and it’s a fresh oil change, looks like all is good It just seemed to be a little higher on my gauge than I remembered.
I think that after finding some mouse droppings in the car I was just being cautious.
I took my fan and hoses apart and found nothing as well as stuck a scope in through my fan openings so I guess all is well.
Thanks everyone for the information, I love this forum.
Mike

220+/- is where I want my air cooled Porsche(s)

anything less than 210 allows condensation and acids to grow in the oil system

That should be fine.

Between lower mark and middle is where my cars run.

Just as a note, in my 1973 manual in the days of only Dino oil, Porsche lists a maximum temperature of 265 F.
As far as Shulisco's comments about Synthetic not having the additives needed to keep the seals from leaking, High Mileage full Synthetics do have additives to prevent seal and gasket leaks, and also reduce sludge build up.