Engine Temp.

[Nick]

Hi all,

recently in the hot weather, while driving in slow moving or stopped traffic the engine temp was rising on my 3.2, in the past I have been used to a 944 (water cooled), I new the engine cooling fan would come in at a certain temperature to cool everything down a bit, but with my 911 being air cooled, if I' m not moving at much e.g. bad town traffic or motorway roadworks etc, what would happen to the 911 engine, does the car have to be moving to allow air cooled engine to stay cool.

Would engine temp reach a certain temp then no more as fan at idle speed would assist in cooling but not as much as moving fast.

Lookily the last time I was stuck in traffic it eased as the temp was rising about the 1st mark (about a 3rd) of way up guage, normal appears to be just below the mark.

Do I need to be concerned, stop and allow engine to cool in these circumstances.

Nick.

 

[Guest]

Hi Nick,

If the engine temp was only about half on the gauge, then you have no cause for concern - this is completely normal.

The marks on the temp gauge are as follows:

- first lower white block...60 degC ( 140 degF)
- next white line up.........90 degS ( 194 degF)
- next white line up........120 degC( 248 degF)
-bottom of next-up red block...150 degC (302 degF)

In simple terms, think of these points as 150/200/250/300 degF.

Your engine needs to get up to 200+ degF in order to boil away the water that condenses in cold weather - so seeing these types of temps is good.

Your engine is air cooled and oil cooled. The big engine cooling fan does most of the work but the oil cooling is also very important. The 3.2 has around 11 litres of oil. In normal operating, the thermostat that sends oil to the front cooler (RHS front wheel arch) won' t even open, but stuck in traffic, temps will rise and the front cooler comes into operation - from memory this is only at 200 degF, so Porsche sees no reason to keep temps below this level. If you carefully feel your oil cooler lines (above the RHS front wheel) when the temp gauge reaches this level, you will feel that they are very hot. Now without airflow, the front cooler does little, so Porsche have thoughtfully added an electric cooling fan. This fan only comes on at 250 degF, so again Porsche are not really all that concerned about temps at this level.

Above 250 degF has been described as " too damn hot" . If you see these types of temps you can start to worry a bit. The 3.2 has IMHO an excess of cooling capacity built in. I have never even had the front cooler fan operating, even after long track sessions and after long traffic jams. The complaint is more often that the temps don' t get up enough on the short drives that we are forced to do. If temps do get really high then yes pull over and switch off. Alternatively spraying water on the front cooler helps (but who keeps a water spray bottle in the car for random traffic jams).

Richard

 

[Guest]

I have just bought my first 911 and had exactly the same question. My normal temp is just below the first mark and in traffic it rises just abobve. Pleased to hear that this is normal.

Thanks for this very detailed explanation.

 

[Guest]

Read this months " Post" for the values of the air-cooled engine... regardless of brand.
Unlike a water cooled engine, in most cases a flat air blower will run cooler than its H2O brother at idle.
In fact, its considered good practice to let the motor idlle for a few minutes after a long hot run on a hot day. Back in Oz, we would often let our cars idle for a considerable time. Unlike the cousins in the swamp, head temps in an air cooled mtr are much higher than any water cooled. Idling allows air movement whilst little fuel is burnt.
C2 (964) owners will tell you (USA & Oz) that closing the rear louvre/wing raises the mtr temp. I can vouch for this; mine has a C2 engine lid with manual switch.