ok my issue is i keep melting coolant overflow bottles and not on the exhaust side, just randomly. last night i was watching it and my coolant was boiling in the tank and actually melted it. this is the 3rd one in a year that has melted on my any ideas guys?

 

What do you have for coolant in it? Sounds like your using straight water?
What does the temp gauge read when it does this?
What year is it? Head gasket repair in the past?
Any leaks, anything else that doesn't seem normal?
Your either getting you engine so hot that it can melt plastic.. Or you have a head gasket out and its your exhaust gases getting pushed it there to melt it.

 

im using 50/50 mix
its a 98 i did the head gasket about 5k miles ago had to get a new head and had a shop check the level of everything on it. also i did the test with the coolant to see f there was hydrocarbons in it and negative. and unfortunalty when the car is running it doesnt boil and the gauge reads normal as soon as i shut it off it boils and i can wait a few min and turn my key on and the temp is pegged out. and no no leaks and i know its not from the exhaust manifold cuz i got some left over AARF suit material (Aircraft Firefighting) and i wrapped the bottle with that and insulation. and that stuff is rated for 2500 degrees. so im at a lost guys.

 

You wrapped a coolant bottle with heat insulation? Out of Curiosity do you have a thermal gun or can you get one? Check temp of the exhaust manifold while it hot, the cat, then after the cat and record readings. When was the coolant put in, who mixed it, with what kind of water? When you Pull off road radiator cap and inspect it, may need replaced. Sounds like either a plug somewhere, bad seal, or poor coolant.

 

Neat little write up on yahoo:
The pressure cap on a cooling system is the key to raising the boiling point of the 50/50 mix of antifreeze and distilled water. For every pound of pressure cap rating the boiling of point of the above mixture raises 3 degrees. If you had plain water in your cooling system with a 15 pound pressure cap the water would boil @ 257 degrees. If you had a 50/50 mix of antifreeze and water the coolant would boil @ 265 degrees with a 15 pound cap. The boiling point would raise to 270 degrees if you had a 60% antifreeze mixture with a 15 pound cap. If you had a 70% mixture the boiling point would raise to 276 drgrees.

Don't be fooled by the old wives tail that by adding a richer antifreeze mixture will keep the complete system cooler. In fact it works just the opposite. As you know pure antifreeze has a higher viscosity rating than plain distilled water. * The higher the antifreeze mixture percentage its ability to adsorb heat from the engine goes down. *The higher the antifreeze mixture percentage also retards the radiator's ability to get rid of the coolant heat.

Race cars use pure water in their cooling systems because it adsorbs heat from the engine and gets rid if it in the radiator *better than any antifreeze mixture.

It's to your cooling systems advantage to mix your pure antifreeze/water mixture to protect the engine from freezeing 10 degrees lower than last years coldest day last winter.

Pure antifreeze boils @ 387 degrees Farenheit in atmosphere.

 

ok so what should i do. would it hurt to just block off the bottle?

 

DO NOT Do that. I would try a radiator cap and thermostat if they haven't been done in a while. They are cheap and I change them on my car when ever I do and kind of coolant service or repair. Next I would try a coolant flush with some new pre-mixed coolant. I still questions a clogged exhaust possibly holding a lot of heat behind your engine. Eliminating the the exhaust gases in the coolant was a huge step in the right direction.

 

clogged exhaust aint it for sure i got a pacesetter long tube, no cat and it dumps under my seats so no clogged exhaust and i know its an old trick would taking the thermostat out help? and not even 3 days ago i flushed the entire system and filled with 50 50 mix

 

It just seems like maybe the system isn't holding pressure and its bleeding off to the the reservoir finding its way out. The radiator cap holds the pressure in the radiator until it hits a certain PSI then releases it to the reservoir. Taking a thermostat out is the same as running with one stuck open. car will just warm up super slow and will continue to clime slowly until it overheats. Because the thermostat holds the coolant in the motor until it reaches a certain temperature, it then exchanges the fluid in the motor with the radiator. Without the thermostat its contently circulating fluid not giving it time to cool in the radiator.

 

A shop can test your radiator cap and thermostat.

Also are there any CEl lights?

On another thought if your temp is not going up then its most likely that radiator cap.