werk-1

Hi all,

Have a 2001 996 coupe C2.

Recently had my water pump and thermostat done. When I got the car back I noticed the coolant level in the expansion tank was a bit low, but I figured they just didn't fill it all the way so no worries.

I have now been checking it regularly and have noticed it has continued dropping down and is now below the "MIN" line.

I took a look under the car and saw what seems to be a leak on the driver side ahead of the transmission leaking down the underbelly of the car. I only have one photo and it is not great be warned, but if anybody knows if this is a common leak point maybe you can help me out. As a point of reference in the photo, you can see the transmission oil drain plug in the foreground and I have circled the leak in red. In the bottom right corner you can see the transmission rubber mount.

Additionally, where else should I be checking for coolant leaks?

New radiators, new expansion tank and almost all coolant EPDM lines have been replaced.

De Jeeper

Leak at the aos would drip there.

hatchetf15

OP - De Jeeper is near 100% correct, oddswise. Look at these locations below. The bottom you should see with a mirror. The top two you can snake a camera in there pretty easily over bank 1 side.

werk-1

Thanks De Jeeper and Hatchetf15, Hatchetf15 where can I find a higher resolution of that image source you provided? I can't quike make out the details.

golock911

There are a number of places to find these diagrams. One of my go-to's is Auto Atlanta.

http://www.autoatlanta.com/porsche-p...section=104-10

Good luck!

11NEUN11

AOS… mine started leaking there. At first few drips turned into a steady stream. My car is a cabriolet and it was impossible to repair w/ motor in. Not my primary car so i dropped the motor and took care of some other maintenance items as well. Good luck in finding your solution. This forum is so awesome and there are ALOT of super knowledgeable people on here to help out.

evoroadster

Why would his loss of coolant be caused by a bad AOS?

De Jeeper

because coolant flows through the factory aos. There is more then 1 way an aos can fail.

Dharn55

I had a slow leak on my car that I could not find for a year or so. Finally went to an AutoZone and got a coolant system pressure tester from their tool loaner program. Took about 10-15 minutes to find the leak, it was a hose clamp on a hose toward the bottom of the expansion tank that was not tight enough and was not easily visible, but with pressure in the system is was pretty easy to find. There are a lot of hoses (something like 26) in these cars and lots of clamps so the pressure tester is very helpful and costs nothing under the loaner program, you buy the tool and get a full refund when you return it!

evoroadster

Would a vacuum test of the AOS detect this type of problem?

The reason I ask is I too have occasionally smelled the sweet aroma of coolant recently. My AOS passes a vacuum test (5" water) but my coolant reservoir shows a very small drop in level from MAX. The reservoir was last changed in 2008 so I plan to change it again since it is past time anyway.

The AOS was changed in 2020.