I've never had the coolant overflow before but I was driving around for ten minutes looking for parking spot with the A/C on. The last time I looked at the temp gauge it was normal. I parked the car and turned it off. I get out and gathered some things from behind the seat and as I'm walking away about 12oz of coolant goes to the ground via overflow hose. I look at the reservoir and there is some on the top of it but I don't know if it came out the cap or passed via pop up valve hose. Level has always been between min & max marks. Coolant not changed recently or needing adding. I drove the car home later that day with no issues. I parked it in my driving and let in run at 2000 rpms until the needle moved up and got out and could hear a low speed fan running which sounded like it was near the oil cooler opening. I then turned on the A/C and I could hear a high speed fan running by the passenger side radiator. Some questions.

1) How many front fans does a 996 GT3 have and where are they located?
2) How does one test the fan operation?
3) Is it likely the radiator cap is bad?

 

Mine did that with bad radiator cap and they go bad quite often..

 

I have a 2001 6tt an had to get the coolant expansion tank replaced last year. Had a very small crack at the bottom and was told its pretty common in these. Probably unrelated but worth a look.

 

I will try and find a place that can check the cap out first to see if it is bad. I don't see any signs of the tank leaking so will rule that out for now. Can anyone answer my first two questions?

 

It sounds like the radiator cap, they do go bad quite often so I would get two next time you purchase.

1.) There are two fans. One behind each of the side radiators.

2.) You can turn the fans on using a scan tool to test them.

 

I had the cap tested and he pumped the pressure up 18lbs. It slowly went down to 7lbs and stabilized. I don't know what the system pressure is and it isn't indicated on the cap. Does this sound like the cap is OK and I should be looking at the purge valve?

I could only hear what sounded like one fan running and when I turned the A/C on I only heard a high speed fan from the passenger side.

 

It should be higher then that, it should stabilize around 11-15lbs.

Both fans should work simultaneously. There is an A/C condenser on each side, so both fans should come on high with the A/C.

 

I only hear a fan on the passenger side. I know there are radiators on both sides but I do remember seeing an xray picture of a 996 GT3 and it only showed a fan on the passenger side however a parts manual suggests there are two fan units. Can anyone verify the number of fan units in the front of the car?

 

Last post in this thread and also checking with another 996 GT3 owner confirms only one fan passenger side GT3. http://forums.rennlist.com/rennforums/997-gt2-gt3-forum/693504-997-1-gt3-no-left-radiator-fan.html. I am going to order 2 new caps and hope that solves the problem. Thanks for all your responses.

 

Get a new cap for $30 bucks..
My cap was bad, but because it screwed around with it too much I cross threaded the reservoir also, so also replaced that. No more problem.