Running a little hot
 

So, if you see this:

http://986forum.com/forums/uploads01...1456359530.jpg

It may be because of this:

http://986forum.com/forums/uploads01...1456359606.jpg

Doing this will not help much:

http://986forum.com/forums/uploads01...1456359678.jpg

*1997 2.5L engine that is in my '00S. Took it out for it's first drive a few days back. I replaced the WP and put in a 160* thermostat after I got back from the drive. Flushed the ********* out of it, but only got one good sized piece of the impeller. Looks like its been bladeless for quite a while. Engine runs great now, but who knows how much longer. It was going to be a spare engine. For now, I think I'll just drive the cr@p out of it and see if it holds together. :p

I'm in the preventative water pump replacement camp (about every 65-70k miles), I changed mine over the summer along with updating to the low temp thermostat. Hopefully, you won't encounter too many issues from the lost impeller bits, several people have continued to drive their cars with impeller bits in the system. They most likely get stuck somewhere in the radiators and oil cooler. It's not ideal, but it probably won't self destruct the engine too quickly. ;)

Any idea what caused the rust?
I've never seen rust like that on an internal component, maybe someone was topping off with tap water?

I have read plenty of times between here and Rennlist that the water pump should be replaced every 3-5 years regardless of mileage. Followed by responses that 3 years is overkill.

This water pump still had the original metal gasket, but looked like it may have been removed and resealed a while ago. I expect that it is original to the 1997 engine. What I really didn't understand is why anyone would remove the thermostat. A quick Google revealed plenty of people thinking that it would help the engine run cooler - bad idea.

I think that the coolant (yellow) had been mixed with tap water. There was no sign of intermix, but plenty of mineral scale in what I flushed out. I'm going to run it for a few months and flush it out again. Hopefully it's still healthy, but I'm not placing any bets.

Way back in the 70's people would take out the thermostat for the summer to help the car run cooler. Did this on 68 Mustangs, 70 Caddies, 64 Chevy's. Cars are more complex now especially our cars.

Do the OEM Porsche water pumps also have plastic impellers? Don't think so.

Thermostat: there is a downside you should mention when you use 80 degree thermostates. The fuel ratio is managed by the ecu. If the ecu thinks the engine isn't warmed up full it adds more fuel. That means more fuel consumption and maybe a little bit more power on the good side. On the bad side the engine oil gets thinned with fuel. I hope everybody knows what that means on the mid to long run and why i'm not a fan of that. Best would be to make shure the ecu thinks the engine is running at 90 degree celsius water temp - while it's running a t 80 degrees celsius.

Regards, Markus

The OEM water pump does use a plastic impeller. The clearance between the impeller and the block is pretty tight. If the bearing in the pump goes, which is often the mode of failure, the impeller scrapes the block. Metal impellers can carve through the passageway, rendering the case-half useless.

The OEM pumps use composite impellers only to prevent tearing up the engine cases.

There are absolutely no downsides to running a 160F thermostat in these cars. Repeated tests (PIWIS, Durametric system) have shown that the DME maintains the exact same fuel trims as it would with the 186F stat, UOA's show absolutely no increase in fuel or water dilution, but also show that the oil break down under high temp/high shear conditions slows because the oil is running cooler. All pluses, no minuses.