dr bob

If you split your time between the oven and the freezer, stay with the original thermostat. The stock one is wide open by 90ºC, so no problems even in the hot climate. In the colder climates, you'll want it so the oil can come up to temperature while driving. Plus your cabin heat will work.

GregBBRD

And the combustion chamber temperature will be correct for the amount of fuel injected and the amount of ignition timing the Porsche enginners designed in.

Lower temperature thermostats and fan switches are not a good idea.

Alan

Ahh No! - Not close

Clearly you don't live anywhere really hot. At 110F(+) you likely wont see 2.5 bar (or anything close) when fully heat soaked - even with a good 20W50 oil.

You should mostly be able to avoid pressure warnings - but then again probably not in the air/oil cooler later cars when idling after a long high speed run.

At 120F it gets more ugly still.

The ~good news is that the pressure drops because the oil is highly fluid when hot so it actually pumps more easily without building much back pressure - so oil IS being pumped around the system. This is ~OK right up to the point where it overheats too much and actually starts to break down...

I also believe the oil cooler loops get less efficient when the hot oil pumps this easily too... not what you really want.

Alan

Edward928

This is a great thread, thought I'd post it up because it's summer

AirtekHVAC

Ditto...answered an issue I am having as well! Kudos

dr bob

Following on Greg's excellent advice:

For pre-S4 cars with the mechanical fan and fan clutch, Mark at 928 International has a replacement fan clutch made, one that doesn't suffer a lot of the casual difficulties that the factory piece does. It's listed here: http://shop.928intl.com/Fan-Clutch-7...28-106-112-AM/ at well under a third of the new genuine Porsche part price.

Many forget the warning that the factory fan clutch MUST BE stored with the shaft horizontal, for instance. Else the fluid leaks out. When working on the car they get removed and sit on the bench or in a box on their faces, and the fluid moves out and around. Yes, you can sometimes refill with the Toyota fluid, but unless yours was stored poorly, putting new fluid in a leaking clutch is a stop-gap at best. They do wear out, and the way you tell is by watching the temperature gauge. The electric pusher is there only to supplement the mechanical fan and to boost AC condenser function. As the mechanical does less and less as the clutch fails, most don't notice the difference on the gauge until the electric fan can no longer make up for the failing mechanical fan losses. Then for some reason...

Too often we rush to replace the mechanical primary cooling fan on these cars with electric, thinking that somehow they will be more efficient. They aren't. Driving electric fans requires (drum roll...) electricity from somewhere. By the time you install electric fans capable of moving the same amount of air that the mechanical fan moves, you have seriously exceeded the capacity of the original alternator especially on the earliest cars. There's energy conversion efficiency in the alternator and fan motors to consider; you loose on the conversion from mechanical to electrical, and again from electrical back to mechanical. The tired original primary wiring isn't sufficient either. Unless there's some other compelling reason to change to electric, a working clutch fan will move more air than most of the aftermarket electric fans you would be tempted to try.

928NOOBIE

Maybe already mentioned but when the thermostat was changed did you also replace the rear thermostat seal? In many cases this is neglected and it can be a bit of work to remove it. Cooling system won't operate at correct efficiency without it.

Also if you haven't, buy a new pressure/radiator cap for the coolant reservoir. They are very inexpensive (less than $10 and are also a critical link in the system to ensure not only that the system is operating at the correct pressure but also makes sure any leaks preventing the system operating at correct pressure are identified and fixed.

Use the correct radiator cap...buy from one of the big 3. I buy a new one every year in the spring.