yukonblu

Hey guys, im having a strange problem. When ever i really get into the throttle say about 4500 plus rpms i am having coolant shooting out of my OVER FLOW CAP. And then obviously my engine temp runs really hot due it being low on coolant. Then when i fill the radiator back up and do my normal daily driving everything is fine and my temp stays at about 175. I really have no idea what the problem is. When ever i was getting my car tuned about a week ago they had the same thing happen. But they said they could not find any problem with the car at all. This all started when i had to replace my thermostat about 3 months ago i believe. I don't know if i'm putting to much coolant in the car and creating to much pressure because of this causing it to explode out of the cap or what. I do know whenever i refill the radiator i am not measuring the exact 11.8 qts, i am just filling it up until it is full using my radiator vacuum tool. Anyone have any idea what in the hell is going on here?

Jimbo1367

Did you bleed the air out at the crossover on the front of the heads?

onefast84

I would check the radiator cap, and make sure that there are no air pockets. If that doesn't help, then check for a bad head, or head gasket. You can do this with a combustion gas tested, this tests for combustion gasses in the cooling system.

FU_I_AM_UltraZ

iTrader: (20)

so its shooting out of the cap next to the battery?? I've never seen that lol. It shouldn't be that much pressure in there. on a cold start, take the radiator cap off for a minute or so. check the level and fill as needed. there should not be any air in the system if you fill up the coolling system that way. if you still have problems, then its something else.

dr_whigham

iTrader: (49)

Is your steam line and coolant overflow line mixed up? (right below the cap)

Maybe a crapped out thermostat?

"MAC"

iTrader: (1)

I had my radiator fluid spill out because i was getting power steering fluid mixed in my radiator fluid. It would spill out of the radiator fluid over flow tank tho. I never measure the fluid when i put more radiator fluid in my car. I open the cap and do a cold crack and add till its full, i also turn on and off the heater as well. also you could just need a new radiator cap maybe your cap is busted IDK if you checked that i didn't read it in your O.P (not saying you didn't think of it). Good luck in fixing definitely wanna know what the problem is tho.

yukonblu

No i never did this, never knee i had to.

yukonblu

Any more thoughts here?

Ace111799

iTrader: (6)

Like Dr Whigham said, check the two lines going into the radiator under the cap. The top one should be coming from your coolant bottle. The bottom one should be coming from the steam vent line from the top of the engine. They are easy to accidentally swap. I did this very thing and had similar issues. If they are swapped your system will never pressurize correctly.

yukonblu

Ill check this... but im not sure why they would be swapped.

yukonblu

Checked this.. thats not the problem

"MAC"

iTrader: (1)

try replacing the thermostat again you may just have a bad one. after that flush your radiator out and replace with all new fluid that may work. Also double check to make sure you put the thermostat in correctly not saying you put it in wrong and IDK if it will work if you put it in wrong but like you said it started happening when you changed out the thermostat.

great421

iTrader: (1)

You have a blown head gasket.

Pressure from the combustion chamber is forcing the coolant out.

Have a leakdown test performed on all 8 cylinders - you may have two blown gaskets.

Good luck!

LS6427

iTrader: (2)

Dude.....have you tried a new radiator cap yet, like people have mentioned....?

Blown head gaskets are actually pretty rare.....if they were tuning it though and bounced off the rev limiter they could have blown the head gasket(s) while tuning.......

Blowing them from daily driving it is pretty rare, but it happens.

PUT A NEW radiator cap on, see if that fixes it. If it doesn't, then do the coolant pressure test.

*******WARNING.......if you do a coolant pressure test and the coolant does go somewhere and the pressure drops......you MUST remove all 8 spark plugs BEFORE you attempt to start the engine again. Why.....because if it is a blown gasket, you could be filling a cylinder with coolant. If you do and then try to start it with coolant in a cylinder.....BYE-BYE engine.......you'll snap or bend a rod. Then it's time for an engine rebuild.

.

yukonblu

I've done a pressure test, stays steady at about 24 - 25lbs. And im guessing your talking about the overflow cap, because its not coming out of the radiator cap. But i guess u could call the overflow cap the radiator cap as well. This problem has been going on before i got the tune done. I think it may have started after i replaced the thermostat so maybe its the thermostat, ill go to auto zone and replace the radiator cap and the overflow cap and see where that take me. Ill let u know bro... thanks

LS6427

iTrader: (2)

No. Don't get a new overflow cap. The overflow cap is a meaningless piece of plastic, it does absolutely nothing. You don't even need that cap on there.

Get a new RADIATOR cap. That's the metal cap on the radiator. They wear out and lose there tension. When that happens the pressure from the coolant system can push against the spring lifting it up. When that spring is compressed the pressure from the coolant system then passes the radiator caps little round door that seals the filler neck and then the coolant blows into the overflow tank.....fills it up.....then it comes out of the top.....

.

yukonblu

Ill have a leakdown test on it.. do u know where i can get this done for a reasonable price?

yukonblu

Gotcha... ill get a new cap and let you know.

yukonblu

Bought this Radiator Cap off Amazon.com, gonna see if this fixes the problem.

yukonblu

Ok... replaced the radiator cap and still having the problem. Anymore ideas?