Overflow Tank

[demonyoka420]

Well im down to the very last part of the coolant system i havent yet replaced. And its really makin me go crazy cause after everything ive replaced its still leakin and i cant drive it for more than half an hour without the temp going up and havin to refill it. Heres whats happenin... when i drive slowly it seems to be ok but once i get on it for a little then pop the hood my overflow is usually filled to the top with fluid and bubbling also while leaking around the spot where the neck connects to the tank, which i jb welded together but apparently not good enough. Also it looks like someone superglued or jb welded the top of the cap for the overflow tank, im not really sure why but figured id throw any info in that could help. Ive been looking at some moroso overflow tanks online i just wanna make sure thats def whats wrong before i go ahead and buy one. I just dont understand why the overflow is becoming so pressurized like that and spewing all the coolant out. Oh and one last thing i have a hose techniques silicone hose running from the radiator to the overflow. Thanks and Any help is much appreciated!!!

[mtcookson]

When the car is cool, take off the radiator cap then start the car. If coolant starts coming out or there are a lot of bubbles there's a good chance a head gasket is blown.

I suppose if its overheating that could cause it too so you'd need to track down your overheating issue. Thermostat in good shape? Water pump? Radiator/AC condenser clogged with road debris?

[demonyoka420]

I just did a coolant flush by pouring water in the rad with the small drain plug removed at the bottom of the radiator while the car was started. While doing this i did notice that when i started the car cool water was coming out of the top very slowly with my finger over the overflow outlet. After it warmed up it dropped as the thermostat opened and i shut it down right afterwards. All hoses are new as well as thermostat and water pump. Other than the coolant my car leaks nothing, and only smokes a little bit of grey smoke upon start up after its sat for atleast a day. One of my friends suggested bypassing the heater core to test to see if its some sort of blockage in the heater core, does this sound like something worth doing and are there any other tests or things i should be checking. Any new info to help figure this out is much appreciated!

Also there is no other blackish or anything other than green coloring to my coolant and i have a koyo rad. Just throwing any bit of info out there i can think of to help diagnose why my overflow is becoming pressurized. Oh and the hole right at the top of the tank has been plugged by someone, is this ok or should i drill it out?
Modified by demonyoka420 at 5:42 PM 8/20/2008

[mtcookson]

Hmm... I'm pretty sure the overflow tank is supposed to be vented. I would open it up to vent as it was supposed to and see if that helps. I wouldn't think the heater core being blocked would cause this kind of issue. I've actually had a blocked heater core before and don't recall ever having overflow issues.

[GerryO]

Also check the underside of your valve cover mounted oil filler cap for a sort of muddy, chocolatey brown appearance, as compared to being simply clear golden/dark brown oil coated black, and does the exhaust appear to be steamy?