Hi everyone,
I am having problems overheating, from what I have read here a guage registering in the 200 to 220 is normal but is the bubbling normal?
I had the car into the chevy garage and they said everything was working fine but somehow the bubbling has me paranoid. It only gets hot when in town driving it starts into the red then, when I hit the highway it drops to about 160. My red zone on guage is 250-260, I always shut the car off before it hits that zone, so possibly the fan could kick in then but I thought around 220 it was supposed to kick in Thanks in advance for the help

 

Unless your talking Centegrade that temp should be fine. Go buy some water wetter from autozone it works pretty good, and maybe a 180 t-stat but dont buy the 160 or you will overcycle the coolant and overheat; or at least I did. As for the bubbling I cant really think what it might be, the only thing in the system is the t-stat....which you should replace anyway if the car is old.

Heres a story, stock 305 T/A cruising down the freeway...starts to tick. I check oil pressure...good, I check temp...good...wait...BAM! 280 degrees. Moral of the story: Bad T-Stats RUIN CRAPPY LITTLE 305S! Warped the heads.

 

The fan doesnt kick in on the TPI cars until about 245 degrees and its a last ditch effort to save the engine from overheating. Thats why i put an adjustable aftermarket fan relay from O'reillys.

When it bubbles is the temperature pretty high or is it low? If its overheating yes it will bubble over into the overflow tank, the water/anifreeze mixture is going to boil eventually when you heat it up past 245. Open the cap on the radiator and stick a thermometer in the fluid to see how hot the water temp is compared to the dash reading, that will give you a more accurate picture.

When it boils, water turns from a liquid to a gas state, so that means there is a mass loss of fluid, you need to refill the radiator if you keep boiling it. Check your radiator cap, if its not holding pressure its going to boil over. (water boils at 220 degrees in atmospheric pressure)

Change the thermostat anyway, they are cheap and your engine is very expensive.

Are you seeing white smoke coming from your tailpipe at startup?

 

My radiator use to do that when the temp would get to 240. It concerned me too. In my opinion despite what Chevy states yours is overheating and shouldn't do that. That's what the bubbling is. I did the following to correct it. Got a hydrometer and checked the disolved antifreeze solution. I made sure it was at 50%. Water boils at 212 not 220. Getting that dissolved solution of antifreeze up raises the boiling temp. Replaced my radiator cap with a new one just because mine was old but it still looked good. If yours is releasing pressure early the system is not pressurized enough to raise the boiling temp. As pressure goes up, boiling temp goes up, and visa versa. Cleaned all of the leaves and crap out between my AC condensor and the radiator. There was a a foot deep in leaves stuck in there, and a dead bird. Rinse out the cooling fins. Checked the fans connections and ground, found a nearly broken ground in the wiring loom to fans connection that was causing an intermittant open circuit. Jumpered that out so that I have a good ground. Bought a 180 primary fan switch from TPI Parts that threads into the block under the right exhaust header.
All of this brought my temperature down 20 degrees and it doesn't get hotter than 225 even in Fresno's 110 degree summers.
I didn't figure this all out at once I did the obvious and then one approach at a time until I got it.
Something I have recently done just becuase I wanted to learn how to burn a chip is that I purchased Tuner Pro and an Auto Prom, read my stock chip and the bin files from quite a few others. Fan 1 turns on at 225 and off at 220, with the AC on. Last summer I programed the chip to turn on at 185 and off at 175. When I did this the temperature seldom gets much past 210. If you want you can have TPI Parts program a chip for 30 bucks to turn your fan on at 180 and off where you want it. However you will need a holder that mounts your old chip and your new programmed one so that you can plug it into your ECM. You many not want to go this far but as I stated I'm interested in programming other things in the chip too. The threaded primary switch is a good idea. This helped a lot.
Summit sells a switch that wires into your loom and can bypass the computer command thus allowing you to turn the secondary fans on manually or via the supplied themostat.
Even if you replace the 195 thermostat with a 180 and don't reprogram your secondary fan, or replace the primary switch, the secondary fan won't turn on until 225. The stock primary switch I believe is 195 and thus you will still overheat or run hotter than you want if there are other problems in your system.

 

Check the cap. Make sure it is holding 15PSI. the pressure in the cooling system in also a factor to coolant temp. the higher the pressure on the system along with the coolant mixture can raise the boiling point of the coolant. Even if the temp is normal a cap not maintaining the right pressure can boil out. Don't go any higher than the 15PSI cap cause the complete cooling system might not be able to physically hold higher pressure.
15PSI on plain water can raise the boiling point well above 212F

 

Well thanks for all the help guys, atm the car is in the shop it overheated the other day in town while in a long line at a drive through. steam started pouring out from under the hood so I pulled out of line and slowly opened the hood and water was shooting out of the overflow cap I had it to the full when hot line but the overflow tank was all stretched from pressure and the water was shooting out the cap so I let the car cool down then as soon as I pulled out onto the road it dropped right to 160F. so needless to say I was quite upset and took it right to the Chevy garage. Its been there 4 days so far .
Will keep you posted on the results.

 

Well?

Simplest start would be to check the ratio of antifreeze to water. Based on what you said above, sounds like there could be too much water in the system and not enough antifreeze. Either way, let us know what the Chevy garage said.

 

This is why I don't take my car to "garages" and "mechanics"....

It needs a RADIATOR CAP. $5 and 30 seconds, done.

Anybody that calls themself a "mechanic" but can't figure that out in 4 days doesn't need your money. They need to find a new career.

Once you get it to hold pressure like it's supposed to and quit spewing all the coolant out, put a mix of about 60% water and 40% antifreeze in it; that's about 1½ gallons of AF, the rest water. Water is a better coolant than antifreeze, but AF not only lowers the freezing point, it also raises the boiling point; so you want enough of it in there to do that job, but not so much that it decreases the efficiency of the cooling system. Min 70/30 ratio, max 50/50.

Problem solved.

 

Well into the 3rd garage and its finally fixed. It was an air pocket,,,lol.
I am still half afraid to drive it but it sits and runs and does not over heat now so it must be fixed. The mechanic said it took about 6 hours to get it out.

Thanks for all the help