99 996 in AZ, Overheating.....

Hey everyone, I have a 99 996 c2 with fabspeed exhaust and evoms intake. I have an oil change etc scheduled for the 30th. This is my first summer. It is also my DD. On the way home when traffic is stop and go it goes up to the edge of the temp guage and the AC shuts down. When traffic starts moving and the car is running at a higher speed it cools down. Do you think I am low on fluids or is this normal. What can I do. It is 109 and is hell without AC. I haven't had to stop the car on the road yet, but is it near!!!!! Thanks

Are you sure that's a '99? Sounds like an air cooled! JK...sounds like you have a coolant issue,,,go figure...thermostat?...I'll let the others elaborate.....no clue over here. J

Somebody help me!!!!!!! Please!!!!!!

You need to get it checked. I run in the middle of the "0" or almost to the right side of the "0" in slow traffic in Tucson/PHX. I cleaned out the radiators which I really think helped. You might want to look into that. If you're maxing out the guage you REALLY need to look at it getting checked before it's too late. Hope that helps. FWIW my AC does not shut down. And that's when it's mid August on the 101 in rush hour.

same the rest...sitting in LA traffic...my needle hovers around the O..and maybe to the right like the above. But..I did the fan mod..so I switch does on. Also...I think I read on here that once the AC is on...the fans turn on automatically. I noticed when I had the AC on even in stand still traffic the cars is COOLER. So...yeah the AC shutting down is an issue. Shouldnt happen...at least I dont think.

Back a few years ago in my '99 C2 one of the radiator/condensor cooling fans failed while traveling across AR in August, HOT/HUMID. Didn't take long for me to figure out that I could dramatically reduce the heat load on the engine radiator/cooling system by running the A/C at maximum cooling and recirculate while using, adjusting the blower speed to control the cabin comfort level. Drove all the way home to Seattle that way.

After 8 years, your radiators are probably full of junk. One highly recommended fix is to clean your radiators. Do a search on this, and you'll come up with lots of testimonials to cleaning your radiators. This will require you to take off the front bumper, and then the air conditioner heat exchangers. The writeup below is a GREAT help if you are going to clean it. Also, Loren at Renntech has a sweet writeup for installing a third radiator. I just added one myself - cost was $900 for parts and installation (by Ruf). I probably could have saved a bunch if I did the install myself. But, I'm lazy... You can follow his advice for removal and cleaning, even if you don't want to install the 3rd radiator. (Also if you are not a renntech member, pony up the $ - it's well worth it!) http://www.realtime.net/~rentner/Por.../Radiator.html http://www.renntech.org/forums/index...70&hl=radiator -td

Agree with td73...RennTech is worth visiting and contributing. Reference your car running hot....somehting's wrong, and it doesn't sound like debris in the radiators. To have it get that hot is indicative of the need to get it in for a checkup. I wasn't aware that the AC would shutt down, but I can understand that from an engineering standpoint, Porsche would want to be able to shut down the AC in order to reduce drag on the engine and help cool it down. I've never heard of anyone having their AC go off like that.

Are the fans working? They should be kicking on when the car is that hot. They're pretty easy to hear even with the windows up. When I'm stopped, mine blow up dust or leaves that's sitting on the road. If the fans are running, I'd agree that your radiators are blocked with road debris. If you're low on fluid, the temp light should flash even when the engine is running & cool. You can also tell by pointing a flashlight at the coolant jug when the car is cold. The fluid should come up to the marker line. If it's dry in the jug, you're low. Even on the hottest days in traffic, my temp gage only moves to the right of the zero - max. I have the 3rd radiator but I did it to keep the car cool while running at the track. Even before I installed it, the car didn't overheat in PHX traffic. AC kicking off sound like something electrical.

Thanks fellas, especially those with az traffic experience. Im on my way to check it out now, if not, off to the dreaded dealer..........

Michael-If your in the Phoenix area there is an outstanding shop in Tempe called www.redlinewins.com . I don't know their number as I'm out of town. I think you can find them in the book under Red Line Motorsports-ask for Robert or Jim. Robert is Porsche trained and is extrememly knowledgeable. Hope this helps. Roger B.

If you have never had the bumper cover removed, and the 2 radiators on each side (4 total) cleaned then there is a 90% chance that they are finally clogged with enough crap that the air flow is blocked. Here is the pictures of my neighbors 99 996 that we cleaned out this past year. This is what 8 years of driving in the southwest will suck into your car. This is the front of the first radiator or actually the air-conditioner condenser This is the front of the engine coolant radiator, which is behind the air-conditioner condenser. You have to unfasten the 2 and spread them apart to properly clean this radiator. This is a good job for spray degreaser and a pressure washer with a low pressure nozzle. This should be done to all 996/997/986/987 type cars at least every 5 years, or sooner in areas if the car is driven primarily in rural or suburban areas. It is not that hard to do, it is essentially taking the front bumper cover and the air ducts off, and cleaning off both radiators on each side.

I just did a full coolant flush as recommended by a renntech user. The simple method. The car seems to be running cooler, ill know better after work. Now, the high side of the temp guage is flashing red, although im only running at the right edge of the zeron on 180. What does this mean?

According to the owner's manual (never a bad thing to consult when it comes to the gauges), that means low coolant or a fault in the engine compartment blower (fan).

As Doug said, it probably is low coolant in the reseviour. There is a sensor installed in the bottom of the tank that will activate the flashing light when coolant is low. It may take several fill ups of the tank before all air is removed from the system. It is faster if you park the car after a run, nose down and open the bleeder valve. BTW: Although a coolant change is good for the system, do not expect the engine to run any cooler than it did before simply because you have new antifreeze.

What do you think the problem could be?

Your high coolant temperature is caused by various design flaws with the 996. The 2 biggest flaws include the restriction in the amount of air that can pass over the radiators at slow speeds and the fact that the radiator fan sensors turn on the fans too late and at too high of a temperature. Another contributing factor is the poor quaity of the water pump which causes it to wear quite quickly, thereby reducing the volume of coolant flow at low engine rpms. You'll identify this problem by increasing engine rpms to 1500 and watchiing the coolant temperature drop. The engine was designed to run between 190F - 200F in all conditions. These temperatures can easily be maintained by doing my radiator fan mod which allows you to run the fans at high speed when needed. At speeds below 60 mph, there is not enough air flow to keep the coolant at the targeted temperature unless the fans are engaged.

It's no surprise that the temp light is flashing after a coolant flush. It is a PIA to get all of the air out of the system. It might take a full six-pack of beer with the engine idling and adding fluid now and then. Oh yeah - add the beer to you not the motor - then wait till tomorrow for a test drive.

Thanks for the info everyone, specifically where can this fan mod be found and how much did it run you to perform?

Radiator Fan and Engine Compartment Fan Switch Mod The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance. The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan. Radiator Fans Connect a wire to the ground of the 2 high speed fan relays located on the relay carrier located in the driver�s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point. With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

Double that. Changing the coolant will certainly replenish the anti-corrosve properties of the coolant, but won't solve your root problem which is most probably blocked airflow on the front radiators.

Thanks again, the car went up to about 220-230 today and I sh!$ my pants. If there are issues above 75 degrees, 108 didnt look very good. Looks like my next mod. Did you use a generic switch or a porsche switch? Any pics of the process or are they in the thread?

I posted pictures somewhere on here a long time ago. I used generic switches installed in the batwing only because I was too lazy to go to Porsche for one of their switches. Others have used Porsche switches. I'm almost done making them automatic based on vehicle speed.

Michael, I really do suggest getting the issue fixed before these high temps you're experiencing kills your motor. 220-230 is really high, high enough that personally, I'd would not want to take it out until it's under control. Clean out the radiators and check the fluid levels, do what you can on your own, after that let some one else look at it before we see a new post from you about where the best engine rebuilders are in Phoenix. Personally, I was worried about the high temps in AZ on my car and ended up moving to a place with a lower average temp....strictly for the car....

Agree. Your car is sick and you need a proper diagnosis before you take any more medicine. It sure sounds like the radiators are obstructed. If that's true, the fan mod won't help. See if you can find the root cause on your own. If not, get it into the shop. It should never get that hot - even in the full fury of AZ summer! Best of luck. Now that's a car guy!

chicago land could you please help me with this mod im in libertyville [phone removed] bob do you need 2 switches? where did you ground? can i call you? thanx

Thats a good question. I was under the impression that you run two wires, one from the first relay and one from the second to a single side of the switch. Then you ground the other side of the switch, si or no?

Bob, I sent you a message with my Cell number. One switch will turn on both fans.