nv1271

I had the same problem with overheating in the track. I was running 220-225 F. I did some research and found out that it is very important to have the right concentration of water/coolant. Mine was around 60/40 coolant/water. I removed 2 quarts of the mixture and added distilled water and wetter water. Last weekend on the track I was running 15-20 F cooler. I don't know if it was the wetter water or just the water but it did work

1999Porsche911

If you were able to run at the track in your 3.4 with engine temps of only 200F or less, then it either was a very cool day, your gauge is screwed up, you read the gauge wrong, it was a downhill track, or you were not driving the car for more than 30 minutes. The 3.4 cannot operate at that temperature on hot days without fans running. Be sure that you are interpreting your gauge correctly. You are at 205 degrees if the needle is touching the left side of the 0 in 180. If you hook up your scanner, your see the actual temperature.

nv1271

Before the wetter water addition and the reduction of collant concetration, I was running around 220, it was half way after the 3rd line and before the 250 red line. That was with ambient 90 F at Blackhawk. Last weekend it was running at 2/3 between the 2nd line (180 F) and the 3rd line with 80 F ambient at Gingerman. It never got to the 3rd line. I have seen the needle above the 3rd line at Gingerman in April with 60 F ambient. So it did make a difference. But as I said before, I had over 60% coolant before so I believe that this is what made most of the difference.

1999Porsche911

If your needle was covering the right side of the 0 in 180, your engine temp was 215 -220F By the time you get to the next line, you are above 230.

nv1271

If the 2nd line is 180 and the red line (4th) is 250 then the 3rd should be 215. In anycase by your numbers, I was running 240 before and 220 now. So it is a significant reduction. I was always nervous about my temp and now I'm very happy with the results of my coolant chemistry... Why do you want to spoil my "great achievement"? Why?

1999Porsche911

You did achieve something. You lowered your temp. I don't know why you were running so hot to begin with, but maybe you were low on coolant or had some air in the system. If what you say is true as far as where your gauge was, your were pretty extreme with the engine temp. The line after the 180 line is upwards of 230F. You could have baked a small roast on the manifokd.

1999Porsche911

Dell, you got a PM.

DerekD

I have a supercharge '01 996 and just added a very small amount of water wetter to cure a flashing low coolant light. My car was also running a little warmer than I would like at that time. Even with the small amount, my car is running cooler and the light is no longer flashing.

LVDell

Thanks. PM received.

1999Porsche911

The most likely reason your temp light was flashing was due either to air in the system or low coolant level. It had nothing to do with the coolant temperature. By adding ANY liquid to the cooling system would have stopped the light from flashing. A low coolant level will make your engine run hotter and by topping it off, you simply brought the amount of coolant in the system back to where it should be.

If it sounds too good to be true...it always is.

Electric Lizard

Thanks for all the great info. Mr. 911 it seems that you have been thinking about 996 cooling. I've got a 01 996 that runs on the "0" in Houston summertime stop and go. At a DE this past June in College Station (over 100DegF at radiator level, 30 min runs) it didn't get much above that, if at all. Couple of questions:

1. I suppose that, if I were concerned about the DE temps, the 3rd rad would indeed help. Agreed?
2. How best to independently check the coolant temp. I have a laser thermometer that I use for cooking (it's digital, so it must be accurate!). Could I point this at a part of the engine for a decent reading?
3. Assuming that the dash gauge is accurate, should I even be concerned about the temps I'm seeing?
4. Do you have some info regarding altering fan speed? Don't the fans come on with the AC?
Thanks again.

1999Porsche911

Lizard: One thing you can use to get the accurate reading of the temp is a scanner. Then compare the various needle positions on you gauge to what the scanner says and place it in memory. The 996 gauge is consistant, but misleading, making people think the engine is cooler than it is. One of the things that decreases the performance of the engine is heat, and the hotter the engine, the hotter the intake. The computer also will retard timing as the engine temperature increases, further robbing you of power. Will running DE's with engine temperature of 225 - 230 distroy the car? Unlikely, but it will take it's toll in the long run because your oil temperature is also higher. If you are one of those that run 0w40 at the track when it's 100 degrees, you might consider going with a heavier oil when you run that hot.

Yes, the fans turn on high when the air conditioner is turned on. The immediate result is a drop in engine temperature, but that is short lived as the heat created by running the compressor will eventually out weigh the fan's cooling benefits and you'll be right back to the high temps. Turning the fans on without running the air will reduce engine temps as much as 20%. Having a third radiator also helps at speed.