My car seems to run warm. I am getting temps up to 230 degrees at times in traffic. The seems too warm in my mind. I dynoed the car today and it got up to 240 degrees then it came back down. That is way to hot. Any ideas what the problem could be? Thanks for the help.

 

Not really a problem. Hard usage at low or no speed will take the temp up until the fans come on. Peaks can be as high as what you saw. From the service manual: The PCM commands the low speed fans ON at 108°C (226°F) and OFF at 103°C (217°F). The PCM commands the high speed fans ON at 113°C (235°F) and OFF at 108°C (219°F). On the dyno the engine is producing max power and if sufficient air isn't getting to radiator the engine temp will surge until the high speed cooling fan starts to bring the temp down. Was there a fan in front of the car blowing air into the radiator cavity?
Bill

 

Yes, there was, but not alot of air was getting to the car from what I could tell.

 

Are you running naturally aspirated? If you had it on the dyno, you should have your tuner turn down when the fans come on. A few things to check:

1. Check for debris between the A/C condensor and the radiator.
2. Check that both fans are working (I got bitten by my low speed fan motor being burned out).

 

have you checked for debris blocking your radiator ?

 

Questions: 1) Does the sys. have two fans ?
2) Does each fan have a hi & low setting?
3) Do they come on simultaneously at hi & low?
4) Why does the sys. wait 35 Degrees for the fans to come
on?
5) Why 45 Degrees for Hi speed?
6) Why did the factory set it that way?

 

1) Yes, there are two fans (open your hood and look)

2) Yes, each fan runs in either low or high speed

3) Effectively, they both run together in low speed mode, or high speed mode (there is a few seconds delay while one fan runs high and one runs low until the circuitry adjusts and switches the fans from using a single ground to an individual ground for each fan in high speed mode). Otherwise, they both run together in either low or high speed mode.

4) Why do you think it "waits 35 degrees" ??? It kicks the fans on at the programmed temperatures quoted by Bill. Don't forget this is a pressurized cooling system, the coolant won't boil at 212 degrees ... in fact the ENGINE OVERTEMP alarm doesn't kick in until 256 degrees. Look in your Owner's Manual and read up on what the engine PCM does when the alarm goes off (firing every other cylinder).

5) Still don't understand why you think it is "waiting" .....

6) The factory set it this way because that's how the engineers that designed the engine told them to do it .......

Look, the hotter an engine runs, the more efficient it is. Start a cold engine and the heat being absorbed by the cold engine is energy not available to power the car. The less temperature difference there is between the burning fuel/air mix and the engine itself, the more "heat" available to power the car. Hence most modern cars run "hotter" than engines did even just a few years ago.

 

you need a 160 thermostat and a tune for lower fan temps,i did it and now is much better,no knock retard=

 

Thanks Black Z06 : Wait was not the best word! ... First, I just got a 2000 with 15K. Out side temp. on day of my first drive appx. 65*F. I had the air/heat/ switch set to off. My cruising ( 55mph) coolant temp. was 190* + or - 2*... had to remain at idle for several minutes. The temp. climbed to over 220* maybe 225* at which time it started to come back down... I was looking at the top fan when it came on. My remark was why does it wait 35* for the fan to come on. Doing the math in my head ... 225*@ the point the fan came on verses 190*@ cruise. My point is, why a spread of 35*, make it 10* or even 5*. I guess what I really wounder: is this the way the sys. was designed or do I have a problem. You sound like you know about these things.

 

Read Bill Dearborn's answer. That is how the system works. So yes what you observed is how it is designed.

If you want it changed go to any 'tuner' and have them change the fan on/off settings. When I got my Z06 dyno tuned one little added bonus was getting the fan on/off settings changed to something more reasonable.

 

As Bill Dearborn pointed out in his early response .... that's the way the system is designed.

The cooling system has to be very capable of pulling heat out of the engine. Imagine a day at Willow Springs Raceway where the air temperature may be above 115 degrees and you are driving the engine at high RPM and many periods of wide open throttle. The engine is generating a LOT of heat, but with the airflow through the radiator provided by the movement of the car I've never had an indication that the fans were on until I pulled off the track .... oil temp runs about 250 and water temp at about 230 and the engine just loves it.

The fans are really there for periods when air isn't flowing because the car is stopped or moving very slowly. Imagine sitting in a traffic jam in Phoenix on a hot summer day ... air temp is probably around 120 degrees and the air conditioner is causing the air that's reaching the radiator (the AC condensor is in front of the radiator ... it gets cooled first) to probably be another 20 or 30 degrees warmer. I can guarantee the fans will both be in high speed mode. Conversely, you're sitting in traffic but it is a winter morning in Cleveland, the fans won't have to run any faster than the low speed mode.


The fans only run when neccesary because they draw a lot of current (and current draw is a load on the alternator, which is robbing power from the engine), especially in the high speed mode. Chevy programmed them to come on as little as possibe to save fuel, wear and tear, and because the engine coolant is still well below boiling point in the 220 to 225 range.

 

So...basically tampering with fan settings and thermostat will make the car not run as efficient as it should...however IMHO.... if the fans happen not to come on you`re closer to a desaster than if you were to reset the fans to a lower temp.

On my ol` LT4 I reset the fans using HPP3 and installed a 160*stat.
Car ran at 180-190 in city and 160-170 on freeway. Didn`t feel any loss of engine performance or different fuel consumption.

I`ll get my `04 QS M6 6000M next week and i was debating if i should leave fan settings stock or reprogram them with a 160* stat

Interesting topic

 

2blklt4 - you're right, it is an interesting topic.

To me, programming the fans to come on earlier really has no benefit. Let's assume worst case .... I'm in my Corvette in traffic, it's a hot day, and the coolant temperature is climbing. You're in your Corvette next to me in the same traffic jam ... and your fans are programmed to come on at a lower temperature.

Let's, as I said, make this worst case, both our cars have just had the fuses for the fans fail. Your PCM commands the fans to come on at ... let's just say .... 190 degrees, while mine will wait until 226 degrees before trying to turn on the fans - in either case we're going to both overheat at the same time since neither cars fans will come on .....

EXCEPT ......

Neither one of us will overheat.

My 2001 owner's manual has an explanation on page 5-8 under the heading Engine Overheating - Overheated Engine Protection Mode. Check your manual to see the GM explanation of this system.

This is one COOL system (sorry for the pun) that performs a "miracle". It fires each cylinder only on every other compression stroke. One of every two compression strokes is a "dead" stroke that does not fire. By doing this, the gases flowing through on that dead stroke actually cool the engine. You'll get all kinds of warning lights in this mode (CHECK ENGINE, REDUCED ENGINE POWER, etc.) and the manual warns that once you are able to fix the cooling problem you need to change the oil, but in the meantime you can drive the car (according to the manual) up to 50 miles in an "overheated" condition.

This system was first introduced by Cadillac back in the mid - 1990's, and an automotive magazine decided to "test it out". They got a brand new Cadillac, drained as much coolant out of it as possible, and then drove it around. They were impressed that the car could be driven almost indefinately with no coolant in it.

GM has their problems, but I believe one of their biggest problems is that they do not communicate just how much useful and innovative technology is in their cars. This ability to run an engine without coolant is a (to me) classic example of how f**ked up their marketing is, as so few people realize that this capability is built into our cars.

 

Black Z06....WOW...i bet you that at least half of Chevy technicians don`t know bout that...i guess that sums it up for me and will leave stock temp settings

 

160 stat and a DeWitt's Radiator, never get hot again. WGI back in Sept. 4500-6200 rpms all day long and barely cracked 200. Instead of a band aid fix the source.

 

Mine did the same until I installed a Vinci fan controller and 170 degree thermostat. Works great in Florida, but I wouldn't put on cooler thermostat for cold weather. It'd probably run too cool during the winter.