OK this just started but I have a 160 stat and its tuned for it. This is for the Corvette in the sig.

When I drive now i was stuck in traffic and I went several miles on the interstate and the temp went from 207-217. I know perfect right??? Thats what I was thinkin... THEN!! I stop and smell coolant. its boilin outta the overflow tank. I check the temp by guage and by Hptuners and its 221 on one and 220 on the other.

I just got another 160 stat and im about to get another top for the overflow tank.

Anyone have any insight on this?

 

Find out if your fans are working and check the radiator for trash & debris sucked up from the road.

 

Fans are working. Ill look for trash tomorrow I just replaced the tstat but its dark out so ill check it tomorrow.

 

Instead of throwing parts at it, do a pressure test!

 

^This

 

I have a 160 degree stat in my car and the temps stay around 180 now, i have yet to see it go over 200 degrees, even on upper 90 degree days.
Definitely pressure test the system, make sure the radiator is free of debris and it wouldn't hurt to hose the fins down on the radiator with water.

 

I dont know how to do a pressure test. Im going to google it in a few.
I changed the tstat and the cap. The only things left are the water pump and radiator. There is no trash there...its really clean under there.
The car seems to boil over when I turn it off. I did a highway 15 minute drive stayed between 217-230 went to 234 for about 30 seconds and went back to 226 and stayed there most of the ride. When I turned the car off. It boiled over. I looked at the temps on the scanner and the dash they both were around 225ish while it was boiling over. Its like something is stopped up maybe?

I had a torque tube replaced and an A/C pulley bolt replaced... Which has NOTHING to do with the cooling but when I got it back here I am with issues. I know the shop didnt do it just wonderring if when I damaged the torque tube if maybe I could have damaged something else?

The car runs fine oil pressure fine sounds fine... When I changed the stat there was coolant in the engine for sure. a LOT... With a 160 degree stat and fans programmed I would think it would be as cool as my camaro around 178ish always. Both are lq9 blocks the vette NEVER has been that low always around 190-210 before sometimes 220-235 highway LONG drives.

The oil has no mix in it its clean. The coolant is not cloudy.

 

Was the belt reinstalled correctly? Water pump is number 4 I beleive.

 

Even at 230 plus you still shouldn't be overheating/boiling over. I know you have it tuned for a 160 but even at that high of temps you should be gtg. maybe when you pressure test it (rent a tester from autozone) you will see where the issue lies.. Just for fyi here is what the stock settings are. No need to get a new tstat just throw it in a pot of boiling water and yoo should see it open.

"The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

This is right from the tech manual.

 

So I have to ask. Is is possible to install the belt incorrectly, and still have tension?

 

Exact same question for me too.

Maybe they changed belts and installed the "correct" one 'cause the other one was too big??

 

Yup there are many way to install it incorrectly and still have tension I just had this issue when I first did it. I think at one point I had the belt wrapping around the part where the top coolant hose goes.

 

Ill double check the belt install but I think its probably right. You never know. I have chased my tail many times before on simpler issues.
I have been reading about that coolant overflow tank. And yes to the first/second/and third that suggested a pressure test. I did some reading on that too. BIG thanks to whomever said rent one from autozone. Never thought of that.

Man I really appreciate all of the help and suggestions period. You have no idea of the car issues I have had between the two cars. ON top of that in the past year alone I think I could have brought two of each cars with the loot I spent just to go fast'''''ER!!!

I already ordered a water pump so ill change that regardless. Just because at this point. the more I read and think about it. Im thinking that its a leak somewhere because as someone posted 235 shouldnt boil it over. But it does not a LOT but it does. Plus the Murray cap I purchased from Oriley's wont seal the overflow well only the original cap will so this morning I swapped back to the original cap. Havent cranked it because I had to work but im here cant wait to get home to troubleshoot.

 

So will the pressure test tell him if hes gout A bad pump or tstat? or just that there maybe a leak in the system? my c 5 is running hot as well & pulled the tstat, put it in boiling water & it did nothing, ur car will allways get A little hotter right after u shut it off, that is normal, but it shouldn't be overflowing out of the resivor, are u running spal fans on ur setup?& have u verified the relays are kicking the fans on?

 

Many ways? Really? .....and still have all the accessories turn, etc?

 

Update...The fans turn on for sure...
Rented a pressure checker.. it would pop off after 12psi or so. It wouldnt seal for anything it was the 9300 from autozone. I took the shroud off and cleaned the radiator there was a mat of fiberglass cloth on there the size of your hand in the middle I cleaned the fins and all.
Switched back to my original coolant cap it tightened a LOT tighter than the Murray one I purchased.

With WATER in the system (its getting too costly to use antifreeze that is just leaking out) until I find out why its boiling.

Cranked it up let it idle and wow it stayed around 178 for about 12 minutes or so.. going back and fourth then went down to 171. I took it for a spin about 15 miles of regular driving. stayed pretty cool 208 is where it locked and fuxed between 207 and 208.... then I turned on the A/C....
UH OH!!! it went to like 235 pretty REALLY quick... probably would have went higher but I turned the A/C off went down to 212 stayed there for a while then climbed to 223 where it stayed all the way home.
GET THIS!!!
I stop all is good..... I pop the hood, turn the car off!!! the temp didnt go up really maybe to 225 I think (I kept the HPTUNERS logging) however it boiled a gallon or more of water out!!!! I have my fans set to run for 140 seconds after I shut off.
Water pump is on the way so im changing it regardless.
That A/C spike freaks me out...
When I change the pump this week im flushing it and doing the antifreeze fill by the manual. I also will go to another autozone or advance and rent another pressure checker. Ill update this post.

My posts are long and im attempting to give details so that maybe someone else that has similar issues can use this forum to save some $$$. I know I have from many of the detailed posts here. Thanks for all the input guys. No suggestion is too lame because im no mechanic.. I did my first pressure test today.. hooked it up tried to get it to 15psi I did have it locked but it really wouldnt seal on my tank. When I find one that works ill post where to rent it.

Thanks!!!

 

Pay for another belt and I will show you..It ran and everything worked for a few minutes before the belt shredded

 

Well I have changed the water pump, surge tank, thermostat, and cap. The only two parts left are the radiator and the fans. No leaks detected. I can run as hard as I want for as far as I want. When I stop its still boiling over. I am going to rent another pressure tester today to try that one more time. The last one from AutoZone kept popping off at 12psi. It seems like a pressure issue. I am about to monitor the fan speed when it cools off here in a minute. I can’t check the drivers fan it’s too low to see. But I am going to use a mirror when I check the speeds. Ill surely keep posting up my results. I also flushed it with distilled water. It came out just like it went in all clean. Then I did the coolant fill per GM instructions. All of my power is there. NO chemicals are mixing hell it doesnt even run hot anymore.... it just boils over. I know one fan works well. The other I will have to do a mirror check to really see. I am also going to put my fan settings back to stock to see if they may be the issue.

 

Are you using coolant or just water?

 

I flushed with distilled water to get a good start.. then I put in dexcool 1 gallon of pure 1 gallon of 50/50 dexcool and about a gallon of distilled water.

The instructions say to mix it. So i did instead of buying 3 gallons of premixed.