997.1 oil temperature increases on motorway

[Grahamr76]

First post for me, hoping to get some advice on the following:

When I'm trundling round town the oil temperature stays at about 90c. However when I take it on the motorway it will creep up to around 110c when I'm driving upwards of 60mph. After coming off the motorway and and trundling along for a few minutes and parking up, the oil temp had usually returned to around 90c but the engine smells really hot and you can feel the heat coming off the engine around the rear wheels. I'm not sure the engine fan is working correctly. If the fan is on when I park up it switches off when I turn the ignition off. If I immediately restart the engine the fan stays off, I would've though the fan would come on again.

I have checked the oil levels and the water temperature never moves from 80c.

Any advice gratefully received.

Thanks

Graham

[Pope]

Sounds normal to me.

Rear/mid engined Porsche cars smell in winter/damp/wet muddy conditions; the hot bits generally live next to the wheels where they are spattered in the crap thrown up - the Cats run around 3-600 C in normal use; enough to bake off most things - and the smell after a run is just a characteristic.

The coolant temp is heavily buffered between 80 and 105C (so that temp changes in use don't have the needle waving around and 'concerning' the driver); the oil circuit warms and cools slower than the coolant and is displayed virtually raw so will naturally be seen to rise and fall with use.

Oil temperatures of 115-120 C and higher are possible without any problems whatsoever; it is not considered to be up to 'operating temp' until 90C.

The majority of oil cooling is achieved through the coolant - the oil is passed through an oil/water heat exchanger on top of the engine and heat is transferred / dissipated between the two media depending on the running condition - when the oil is cold the warmer coolant is used to 'heat' the oil; at higher temperatures the opposite occurs.

997's generally run warmer in traffic if the AC is switched off (the airflow across the radiators is minimal and the Condensor fans are off) meaning the coolant temperature is controlled by a set temp threshold (switching on the cooling fans) rather than the thermostat as would be the case when driving at higher speeds.

If you aren't getting any warning lights then I would be happy to keep going - the management system has codes that it can display if expected parameters are breached.

Early 997.1's had a recall that reprogrammed the stage 1 engine purge fan - it had a tendency to run on and affect the wiring - but I haven't seen a car without the campaign applied for about 6-7 yrs; put your VIN into the Porsche Campaign web app to be sure.

[Grahamr76]

Thanks, I really appreciate your reply! I guess the main comfort is that the engine management would warm me if there was a real problem.

I did a couple of other 'tests' yesterday. If I accelerate hard off a roundabout up to 60 or coming onto a motorway from the slip road then again the temperature will rise to 100. If i stay at 80 the temp will stay around 100. If drop down to 60 it will slowly return to 90.

I'll have the fan checked out.

Thanks again for your input.

[ooid]

I'm not sure if your car behaves "normal" although pope has the senior word here! -well should be!

Here is our usual readings when we had 997 C2 in the family;

Motorway Cruising (65-70mph)
Oil: 100-105
Coolant: 90

Heavy Traffic
Oil: 105-110
Coolant: 90

(Actually even my current cars give very similar readings on these driving patterns, and they do not have flat 6 layout)

Yes, the gauge is not correct for coolant. It will stay as 90, and not give any specific info unlike early 986 or 996 where you can see the gauge climbs immediately if stuck in traffic.

You would not get any warning about super-hot oil or coolant on 997 gen1,until s-h-i-t hits the fan but the point is, most of these engine damages pretty badly due to insufficient cooling system. (Our car needed an engine replacement after 4 years old, and sold immediately)

Loads of more info below from hartech in terms of cooling inefficiencies;

https://www.pistonheads.com/gassing/topic.asp?h=0&...

[Grahamr76]

Thanks ooid.

Does seem strange that my readings are different to yours. Your car runs hotter in traffic and cooler on the motorway whereas mine is the opposite.

The Hartec thread is very useful. I was thinking of taking it to them for its next service or work and see what they think and get a low temp thermostat fitted etc.