Changed out the AOS, now oil in the coolant... intermix?

[Beninki]

I was able to change out my Failing AOS on my 2000 C4 Tip Cab with the help of an amalgam of the various great DIYs here and on Rennlist. I just drove the car 50 miles or so, with no overheating or other issues. Also, no more smoke on accelleration. I then went to check my fluids and discovered a serious amount of oil in the coolant reservoir. It looks like a milkshake... It seems suspect that it happened at the same time as the AOS replacement.

Is there any chance that in my tired state that I reversed the two small hoses on the AOS? Would that even make a difference? What if I received a defective AOS from Porsche?

There was no sign of any oil in the reservoir previously. I have been trying to find a diagram of the internals of an AOS and the hose connections, but haven't had any luck.

Any thoughts would be appreciated. I would thank you in advance for assuming that it is something other than intermix and not jumping to conclusions.

Thanks!

Best,

Tom

[JFP in PA]

The AOS unit for the 996 has water passages in it. You need to retrace your install.............

Edited June 14, 2012 by JFP in PA

[logray]

+1 check your lines.

The AOS is a fiddly bit with lots of nasty tenticles.

There is the hard piece that slips into the 1-3 case side.

There is the "rubber bellows" that goes into the 1-3 head.

There is the passenger side top exit coolant hose which goes to the small coolant passage cover on the 1-3 case side via a plastic union.

Then the rear exit top coolant hose which goes into the small drivers side rear "small" coolant hose (going from bottom of coolant reservior to heater core loop and water pump).

Then you have the case vents, with orings and hard plastic lines, one going to the plenum behind the throttle body.

Another going to the breather on top of the 4-6 head.

whew. Did I get it all? ;)

[987_RDC]

Sounds like you had intermix originally which killed your last AOS and any future one since the mix eats plastic seals. If your oil isnt milkshake then you might want to pressure test the oil cooler.

[Beninki]

Re-checked all the lines last night. Everything is as it should be. I am going to drain the oil this evening and see what is up. The oil cooler is of course suspect as is a cracked head. Since my car is a MY2000 and they are notorious for bad heads, I am prepared for the worst.

[987_RDC]

Hopefully it is the oil cooler. One word of caution is to not buy a used oil cooler as replacement. (might be obvious)

[Beninki]

Thanks for the comments. The strange thing is that the car isn't running hot. I assume that with a cracked head, you would have overheating issues.

[JFP in PA]

Thanks for the comments. The strange thing is that the car isn't running hot. I assume that with a cracked head, you would have overheating issues.

Not necessarily; cracked heads are often found because of intermix issues, not over heating.

[fpb111]

What did the oil look like when you drained it?

[Beninki]

I haven't had the chance yet. I am going to try to get to it soon. The oil on the dipstick is perfectly clean, but I know that is not a good indicator of the condition of the rest of the oil.