I just purchased a used 2000 Vert, 6 spd with about 50,000 miles.
I was driving from Cincinnati to Atlanta and all seemed well. Outside temp was 50 degrees, the temp guage showed 200 degrees (only 220 is really shown on guage).
I had to stop for a freeway backup and the temp guage went up to 220, then edged up another mark (230 I assume).
I got off the freeway, checked the fuses, all OK.
As long as I ran at 50 mph or higher the temp guage stayed at about 200 or 205 degrees. As soon as I slowed to a stop, the temp went up in about 3 to 5 minutes. I checked with the A/C on and neither fan was running.
Does the ECM control the fans based on the temp reading from the sending unit that also feeds the dashboard guage? If so, would this be a relay problem?
Is this a "dealer" fix?
JD

 

There are three relays that control the fans as commanded by the computer. Low speed = both fans are wired in series so both run slow; high speed = both fans are wired in parallel so both run at full speed. If one fan motor has failed open then the other fan will run on the high speed setting but neither at the low speed setting. If neither fan operates when the engine is hot and the fuses are good then focus on the relays, the contacts could be worn out after 50,000 miles.

 

Check for debri blocking the condensors......


DH

 

If I remove the relays, does the top part come off?
Can I detect a bad relay by just looking at it or does it require using some type of test equipment?
JD

 

Those temps are normal. The slow speed fans are programmed to come on at about 220, the high speed fans about 230. With little airflow the coolant temp will creep up to those numbers and cycle between them. The thermostat opens at about 194 or so which will control the low temp setting which is why you normally see about 200 in high air flow conditions.

Many guys don't like these temps and get a 180 or even a 160 thermostat and reprogram their fans to come on at a lower temp than stock.

But... the fans should be on with the AC on, and they should be on if the coolant temp is over about 220, so if you fans where off in these conditions, you have a problem.

 

I'm in San Antonio Texas and I see those same temp readings with my car especially if the AC is off. It will go up around 230 at a stop. If the AC is on it might be around 220 or so. Even in cold weather I might see the same temp readings. Just my 2¢.

 

Normal for stock.

 

GM claims it's normal but it is simply to help them comply with low emissions and high fuel economy, but these temps are hard on the engine. you can upgrade the radiator and change the T-stat to a 180. This will put less dependance on the fans and cool the engine more efficiently. Take a look at how wimpy the radiator is. I've seen the same size on Honda's. I found a Dewitts supplier that sells them for $465 and the change out is pretty easy. Pm me if you want there website.

 

great info here!

I put a 180 T-Stat in my 97 that was running upwards of 235-238 on the highway...I also did the debris check in the front shroud. With the stat change- I stay around 190 normal driving and never more then 210-215 in stop and go traffic. There are nay sayers on the board that suggest a t-stat has nothing to do with changing the temps- I say to them cuz if you open up the t-stat earlier the coolant starts flowing earlier thus the engine does not heat up as high or stay as high as it did with the higher t-stat setting. as you can see- I dropped a good amount of heat!

 

I did a test in my driveway today and here is the short version of what I found. I should point out that I can see the fan blades of the driver side fan (left) but I can't really tell when it comes on. I can see the right side fan clearly.
Let engine idle, watched digital temp guage and fans
190 on digi, no fans
221 on digi, no fans that I can tell (maybe left is on, don't know)
Turned A/C on, right fan came on, temp went to 225, then started to drop,
221, 219, 217,
Turned A/C off, right fan went off,
219, 221, 226, left fan on now for sure
right fan came on,
225, 222, 219 right fan went off,
220 turned A/C on again, right fan came on,
219, 217

Shut engine off. I guess all is working according to GM specs.
I'm not wild about these temps but for now I will monitor it with the digital display while I drive. Lower tstat may be next move.
Thanks for all the replys. JD

 

Just keep in mind that to really get max benefit, you need to have your fans programmed to come on at a lower temp. A lower T-stat will only start the water flowing at a colder temp, but the upper temp is usually controlled by the fan setpoint.

P.S. Based on the detailed info you provided, your numbers do look normal to me.

 

True story!

 

In that your car has been on the road for 4-5 years I would be sure there is no build up of road junk(paper/leaves/etc. between the two radiators. Climb under the car and take a look. Also you can remove the cover that is just below the air bridge to get at the upper most area.
Good luck

BTW get a lower thermostat if you are not happy with these temps or a VINCE fan controller to change When the fans kick on.

 

If GM were to do like all other car manufacturers people would not mistakenly think that their car was overheating. All modern cars run at these temperatures which are normal. If you notice a ford truck for instance just has a guage with "H" and "C" at the ends. A typical car runs at or near the boiling temp for water to burn off water in the oil. While 192 will accomplish this too there is always a range of temps for any car. If your corvette had no numbers and you looked at the guage it would be in the middle for 220 and 270 is overheating.

A 180 will lower the temps if fans are reprogrammed if you need to see them lower but 230 on a modern car is fine.

 

That's all good but that really only applies to the family cruiser or your SUV. For those of us who have power adders and/or like spirited driving, those standard GM temps rise fast and uncontrolled. I still can't understand why GM would put such a small radiator in a car like ours that is a bottom breather to start with. I guess it depends if you want your car to last longer or not.

 

For what it's worth, a lot of these temperature 'problems' would probably be a mute point if the engine compartment could get fresh air around it or at least there was a way of extracting the hot underhood air. I haven't tried this yet but some others who have can chime in. If you remove the fog light frame holder and replace it with a screen, outside air can get up into the engine compartment and pass over the engine, cooling it down a bit. I've seen these screens that still allow you to keep your foglights but let outside air in. Even the side vents on the fenders could work as a heat extractor if they were open to the engine compartment. In order for an engine to work efficiently, it must retain a certain level of heat. These engines are all aluminum and therefore cast off heat faster than a cast iron counterpart. Insufficient heat is just as bad as too much heat for engine longevity. It's a fine balance that the GM engineers have to find. I think a lot of us grew up in the age of 180 or 190 being normal but that is no longer the norm.

 

to modify the fans, do you use some type of a controller or reprogram something?

 

Excellent points made here. By getting more air over the radiator and not neccessarily venting the engine compartment you can control the engine temp better. By having free flowing air pass by the block the engine would be unevenly temp controlled. But here's the rub. If you really get on the car and push it the temps can't be maintained very well. It gets to a point of heat soak that no matter how fast you go the temp will rise and rise to over 250 and that's just not good. Also for us A4 guys the tranny temps can't be controlled either and 250 on the tranny is bad. With a better radiator you allow the T-stat to do its job by controlling the flow and maintaining the appropriate temp. If the radiator is max'd out the only recourse is pulling off the road to cool down. I don't think the General expected us to actually use our cars, only shine them.

 

What problems? And who has longevity problems? I hear people getting 150k miles on a stock ls1 engine. 235 degrees isn't overheating and is not a longevity issue. The only issue with that temp is if your are not running synthetic oil. If you are running a power adder I don't think that it is GM's responsibility to redesign the car for your application.

I don't know what rising out of control means but if I left my corvette standing in the driveway for hours just at idle on a 100 degree day it would not go over 232 degrees....ever. 260 isnt overheating. If it bothers you then change the thermostat but claiming it is bad for the motor is myth...every car runs at these temps these days. No production car runs at 180 degrees. Saying there is a problem with it is BS and you may wish to show just one example of someone with temp related problems in normal use. For a daily driver, the cooling system is overkill. If you run a 450rwhp motor then you may need additional cooling

As for the transmission at 250 degrees...like I said, it will never get that high. If your car is hitting 250 then there is something wrong with your cooling system or you're in the desert. No matter what I have ever done with either of my heavily modded vettes I have never seen over 232 which is a safe and normal temperature.

Lets get to the point here:HAS ANYONE HAD MECAHNICAL BREAKDOWN OR DAMAGE FROM RUNNING THESE TEMPS WITH A PROPERLY FUNCTIONING COOLING SYSTEM? Please let us know your personal actual/experience with this breakdown....ie blown head gasket, damage to the transmission....ect. Not interested with outdated opinions.

 

...very well put.