Hey guys, I have a 2000 Corvette and it over heated the other day to full 260+, I just changed the thermostat and now when idling the temp will go to 235 and the fans will turn on the temp will continue to rise to 240-245 then due to the fans drop back down to 220-225. Once the fans turn off again it will rise back up and fall back down, it continues this cycle. Is this normal or is hitting 245 way too high. Fans turn on at 235 consistently.

 

Sounds perfectly normal, although you should always consult your owner's manual for best answer.

 

The temps shouldn't cycle like that. With a stock T stat, you should see 220 all day long. It can rise to 235 and still be OK. If its going to 250+ something is wrong

Some things to check:

Unrestricted air flow through the radiator! Look up into the front air opening for the radiator under the facia and see if there is any trash, dirt, debris in the opening.

Is the 1 inch space between the radiator and the AC Condenser dirt free?

Do BOTH fans come on??

What is the coolant level and are you building up cooling system pressure when the engine is at full operating temp?

What is the coolant reservoir cap pressure rating? 15 psi or 18 psi? GM up graded the cap and changed the pressure to 18 psi. Recommend getting the updated cap if yours is 15 psi..

Have you BURPED the block of any built up air? Its easy to do. Find the FRONT steam cross over pipe connection on the front "top" of the passengers and drivers head. When the engine is up to temp and the system is pressurized, just CRACK the fastener that secures the coolant pipe to the head and see if air or coolant comes out. If air comes out, keep it cracked till you see coolant. Retighten the fastener. Do both sides.

What is your coolant to water ratio? 50%/50% 60%/40% etc.....

WARNING! DO NOT REMOVE THE CROSSOVER TUBE FASTNER when the engine is hot and the system is pressurized!!!!!! Hot coolant will spew out when the fastener is removed!!

Bill

 

On another level, you could still have a bad T Stat.. Don't take that for granted.. If you change it, I would get a 180 or 185 deg stat.

 

First question is when do you think your car was running normally and what, if anything, has been done to the car since then?

what were the driving and ambient temperature conditions when you overheated? Need more information. There are many possibilities.
Water side- low coolant, plugged radiator, failed water pump, stuck thermostat
Air side- blocked radiator, failed fans, Missing air dam
Engine side- Blown head gasket. Recently a forum member had plugged converters and was over heating

 

Stock fan settings on your car are #1 fan ON at 225* and OFF at 219*
#2 fan ON at 235* and OFF at 227*
The STOCK thermostat starts to open at 198* and fully opens about 205*
I have tuned 3000+ LS engines and as far as I am concerned these operating temps are way TOO HOT A LS engine runs best at about 190-195* The only way to make your engine run cooler is this
1 make sure the A/C condenser is not clogged with weeds and debris
2 Make sure your radiator is also free of debris
3 Install a 160* thermostat on your car ( it will not run that cold but about 190 *
4 A must--- have a tuner re set your fans ON/OFF settings as such
#1 ON at 204 OFF at 198
#2 ON at 207 OFF at 205
This will make your car run far cooler with No detonation or overheating !!
Also The 2014+ Corvettes because of the direct injection system these cars operate at a much warmer temp Average temps on a new LT engine in about 205-210*

 

Just went through this exact problem. Changed water pump when new 160 stat. Old stat was 170 car always ran around 180 185ish always except on power run. New stsat 235 back down to 220ish this would go back and forth for away then 240 250. Then shut down. I took the stat out and heated it up IN WATER to 160 and the stat open. WTF. I'm thinking i have to change the pump again. But i had a 187 stat new from delco and the other one was Mr. Gasket. CHANGED AND Car runs perfect at 200 to 207 highest. MY ONLY CONCLUSION IS THAT WHEN THE TEMPS HEAT UP AND THE PRESSURE STARTS TO BUILD THE 160 STAT SPRING IS NOT STRONG ENOUGH TO OPEN. WHEN I COMPARED THE SIDE BY SIDE YOU CAN TELL THE DIFF IN QUALITY. HOPE THIS HELPS

 

I the cooling system, the pressure is equal on each side of the thermostat. There was something else afoot.

 

Yes that is a diff situation then mine, sorry. Yes i had the lower hose 160ish with very little psi and the higher hose was over 220ish high psi.

 

My coolant is overheating to the point where it begins to steam out of the 18 rated cap and i am running 50/50 coolant. However i noticed but am not quite sure but I feel like my fans are only turning on at hi temp 235 when other post say they should turn on low at 225 or so. Could that be the culprit? I just really don't imagine a fan causing my coolant to literally boil

 

When my car was running normal I was staying consistently at 210 while driving and max 230 when idling, it was nighttime when it over heated so it probably was around 60 or 70 degrees, I noticed smoke comming out of my hood but it was steam from the coolant reservoir

 

Thanks for the fan info, I believe my fans aren't turning on at the lower end temp 225 and only at 235
Edit: Fans are working properly

 

The thermostat I put in is 187 but still overheats

 

. What brand?? I don't thick Bruning is goi going to help. The wY i always do is keep cap loose start the car and when fluid starts coming out tight it. Then let it cool down and loosen the cap very slowly to let the air out. But if fluid starts coming out just thighen back down. Don't do it if not comfortable. Never had. Problem.
might have a bad stat. I didn't think it was possible but worked for me

 

Two identical posts simultaneously running

 

I have a 2000, too. That said, IF.....IF your fans are working OK now, as you say in edit, and IF you have a GOOD 187° Stat, and, as others have said, IF your radiator isnt blocked with debris, 225-235° isn't overheating.....Yet. If all those things mentioned earlier are good, and you're running at 250°+, it has to be the either there's an air lock somewhere in the engine/cooling system, an internally plugged radiator, bad water pump, or a blown head gasket. I agree with Bill Curlee-225°-235° while cruising around town is normal. Just because you installed a cooler Stat doesn't mean it will run that much cooler without increasing cooling ability, as in a larger radiator. It might when the car and radiator are newer, but not at 15+ years old. My stock 2000 Stat was 212°. Just out of curiosity, when is the last time the coolant was flushed/changed? Also, what ambient temps are you running in? If it's 105°, obviously the engine will run warmer than in 40° temps.

 

I just answer which one is first.

 

Another poster mentioned checking your AC condenser in front of the radiator. Have you done this? You need to ensure it is clear of debris and more importantly SAND lodged between the fins. These cars are nearing 20 years old and have seen plenty of road miles to collect dirt. These posts are getting more and more frequent as the population of miled cars increases. YOUR CONDENSER MUST BE CLEAR OR YOU WILL OVERHEAT