dsbl

You can add a manual switch to the high speed fan relays letting you turn them on whenever while still retaining the automatic control, even at highway speeds having the fan running will help pass more air. If both fans are completely broken then the car will overheat at some point when idling, however the dual fan dual speed setup is somewhat failure tolerant in that the car can still decently cool itself with only one fan, or a fan only working in one mode. The 3rd radiator helps as you have more coolant and more cooling area, but it doesn't have a fan so you do need to be at speed for it to be contributing, plus you then have to figure out where to route the output air (or if you really care about it, more of a track consideration).

Chess911

Well happened again today going up the mountain albeit temps were in the 70s instead of 90s. Pulled off to the side of the road and idled for about 10 minutes and the engine temp dropped back down to normal. Had the A/C on. Glad I was at the summit by then. The rest of the way was flat or downhill and engine temps remained normal. I turned off the A/C as well. Turned into a lovely 3ish hour drive round trip.

Fans appear to be working. The passenger fan appears to blow air from below the bumper here where as the driver fan blows straight out of the grill opening. Is that normal?

Mike Murphy

Both fans should suck air from the front and dump air into the front tire area.

purelydriving

My guess would be that there is an issue with the fan that is blowing air out of the front bumper as the fans should be blowing air into the front bumper

De Jeeper

Yea the fans pull air from the front of the car through the rad and down out the bottom of the bumper.

Did u check or perform any of the tests (pull front bumper or test fans) between the 2 drives? If not why would u think the problem would just go away? Not trying to scare u and im not even sure how hot u got your motor as the gauge sucks but a poor performing coolant system in these cars is the kiss of death and a good way to spend $25k on a rebuild.

GC996

Chess, if you don't have the DIY skillset, best thing to do is find a GREAT indy that knows the 996 extremely well and have them go over your cooling system with a fine tooth comb.

I'd be a little worried if my 996 was overheating going up a long hill. Good news is that its fixable.

Don't forget to change your water pump as well if it hasn't been replaced in the last 7 years or so. The plastic fan blades can break off and get lodged in the engine causing cracking from excess heat. No biggie, just replace it every so often.

These cars are really durable as he'll. But parts have to be replaced over time. Remember, it's a 20+ year old car. Plastic and rubber deteriorates with use and age. So does metal from friction. If yiu want an engine refresh checklist, just let us know.

pdxmotorhead

i've crossed 7000 foot mountain passes at 100F+ and not budged the needle past center of the 0 on the 180... Oh and I was averaging 85mph..

+1 on your fan being screwed up, it should have 2 speeds on each side pulling air in the front and blowing it out the wheel well.
Someone has done something fairly wrong to get that fan to run in reverse. And if they did that I would suspect everything, its not a easy mistake to make.

I agree with the note above, pay a good indy who knows 996 cars, don't assume an air cooled shop can do it.
The 25k repair bill is no joke, one of the more common fails is a cracked cylinder or head from overheating....

With warm engine sitting parked, both fans should be running at low speed, turn on AC and both fans should spin up to high.

If something isn't working stop driving it.. Till its fixed.
If your temp goes past the 180 something needs attention unless your in super crazy heat, or in severe stop and go traffic for a long event.
.

Mike Murphy

That helps

Having been on the track several times, my engine and brakes always get hit when I have to come off the track suddenly with zero airflow after hammering the car.

ssherman68

From your description it sounds like one of your fans is rotating backwards.

If you're going under 50 you'll see the temperature creep above its normal range (between 180 and the center of the "0"). I had a similar situation to yours a few months ago. I was driving aggressively up a twisty mountain road in 70º temps. I was in 2nd gear most of the way and going between 20 and 50 MPH. By the time I got to the top my temp was halfway between the last line and red zone. High revs and slower speeds. If you're at freeway speeds 50+ they'll usually stay nailed at 180º all day no matter what the temperature is. These cars really like 50+ MPH air flowing across the radiators.

pdxmotorhead

on a 100 Degree day, I was cruising on a stretch of interstate in eastern Oregon before I got my engine done,
The temps literally went down the faster I went.. (Only meybe I was in mexico... ) Mine used to get up tp about 200,
but as I sped up past 55, the temp dropped till it was stable at 180, and speed was 95. Did not take long at all.