Quick coolant question before I head off to work. I just changed the Thermostat, I have a Koyo Radiator, and for some reason, ever since I bled my coolant system, it has spit coolant out of the overflow, everytime it shuts down. Once you crank the car up, the buzzer comes on, so I'll top it off. After I drive it, even a few blocks, it spills over. Everytime it does it, it comes from the overflow. I have the aluminum AST, with a new cap, all the lines and hoses are fine (read new), and there are no other leaks anywhere. I am boggled by this, and freaking bc I have to carry more coolant than I normally do when I go places. Any help would be wonderful guys and gals. Appreciate it, off to work now.

 

It sounds like the system isn't sealing?? What do you do after it blows over ("After I drive it, even a few blocks, it spills over")??? Does it stop leaking..?

I don't know where you got your new radiator cap, but that could be the problem. I have seen many defective rad caps. I've also come across rad caps that release below atmospheric pressure, like .9 atm, or something. What does your new cap say?

 

I changed all the rad caps and replaced the overflow line that goes from the AST to the overflow tank. I think the line from the the AST to overflow tank was the fix. If this line has a slight leak it will not allow the coolant to syphon back into the engine when it cools.

 

Also check for dirt around the cap. I found that the cap wasn't sealing on the top seal because of some very little debris that was there. Just getting this cleaned up helped alot .

 

don't overfill the overflow, check dip stick cold.

 

I haven't been around it to see how long or how much it leaks out. Usually does it when I get to work, so I don't get to see it, until 12 hours later. It is a Pettit AST, so when I broke the cap, I replaced it with the same one, from Autozone. I made sure it was the same cap and all. I will try the line from AST to Overflow. If I am not mistaken that line has a split in it anyways doesn't it? Thanks for the info guys, keep it coming.

Also, I was thinking of replacing the main cap, what size is the best for us? Thanks again.