This morning when I was walking towards my car I noticed a leak underneath that went all the way down my driveway but had no color to it(like it was from condensation) so I thought nothing of it. Started my car and the coolant buzzer came on. I turned it off immediately and popped the hood. My AST and filler neck(by airpump) were both empty. The leak was coming from the resevoir below the passenger headlight. I topped off the coolant and started the car. No buzzer. Drove to work and as soon as I park and turn the car off coolant came pouring out of I guess the top of the resevoir(below passenger headlight). I havent had time to really look at it since Im at work but i just wanted to see if you guys could maybe give me some insight. I have changed nothing under my hood except for a fuel filter so I dont know whats going on. Is there some kind of seal on top of the resevoir that sometimes needs replaced on 3rd gens?

 

I know its not the motor. do these things usually leak from the top?... cause it seems like thats where its coming from. Thats why I think its gotta be the hose coming into it. My dad is sealing the driveway tomorrow so Im not allowed to work on the car in the driveway tonight! Guess Ill have to just jack her up in the street.

 

I think I may have a similar problem.....a few days ago the buzzer light came on, and since I had flushed the system a few weeks ago I thought that it was just some more air that had finally come up to the filler neck (gee, thanks for the great job AST). However, I also noticed that the overflow tank was higher than the 'F' mark.

Anyway, I put in a few cups to kill the buzzer, and when I parked it later....it all came spilling back out (much as I expected it would). Now I wonder what the conditions are that would cause the excess coolant to not flow back into the engine after shutdown/cooling?

So....back to your problem......after pulling into my spot yesterday I noticed that there was a yard long wet trail leading towards, but not all the way to, my car. If you happen to find a leak, let me know where, etc.

 

I know theres a leak. Its coming from the coolant resevior under the passenger head light assembly. Looks like its coming from the hose that hooks in to the top of it. Ill give you more specifics tonight hopefully.

 

There is a hole in top of the overflow tank. I had the same problem.
If you over fill at the neck or AST the excess goes to overflow tank. Then out the hole in the top.

 

Yes that all makes sense......... but I havent touched my coolant in probably 3 months. Then all of the sudden it overflowed while sitting overnight? That is just not adding up. Maybe your right though. Maybe the coolant buzzer was on because of an air pocket or something..? And then i just overfilled it. Shouldnt there be coolant in the AST and thermostat housing when the car is off though? I checked it before driving and they were empty.

 

Try filling our system from the hose at the back your throttle body. There is a 3/8" water hose back there, it is highest point of the cooling system. Air can get trapped in there. Remove both filler neck and AST caps. Then remove hose and with funnel fill hose until see water at top of filler neck. I had to do this twice...no more Low Coolant Buzzer.

 

Maybe your radiator cap went bad.

 

A hole in any part of your cooling system, or a bad cap, will cause coolant to stay in your overflow and not be drawn back into the system when the car cools. Tom

 

Could it be a problem then, if the filler neck to the overflow is not sealed? Because, I believe that is the case.

 

Not saying that isnt a problem........ but thats not the one it was leaking from.

 

That makes a whole lot of sense, actually. My filler neck cap -is- getting pretty crappy, so I'll see about getting a new one.

Would it explain why I sometimes see slightly higher temperatures than normal as well? Not enough pressure in the system.....allowing the fluids to heat up more than they usually would....

 

BLKFD, That's a little different, as the overflow is vented to atmosphere. I meant like all the pressurized parts. Tom

 

Alien7, It's a good place to start The sealing area on the filler neck on my AST had two dings in it when I bought my car. I was spilling coolant out my overflow and it was not returning to the system. Dressed out the dings and all is well. Tom

 

Hmmm.... everything seems fine now. Heres what I think happened:

I leaked a little coolant because my radiator cap wasnt on correctly. I checked my fluids added more than put the cap back correctly. All the coolant I added later overflowed out of the resevoir when I turned the car off. Now when I check the Coolant levels the AST and the thermostat housing are both full. I think Im going have a friend that works at a mitsubishi dealership pressure test my system today just in case. Does this make any sense?

 

Yes

 

I also had a similar problem. I found the radiator cap wasn't holding the correct pressure and would dump coolant into the resevoir until collant system was empty.

 

Before you spend the $20 each (massive rip-off) for the filler & AST caps:

I had the same overflow problem. There wasn't enough vacuum to suck the coolant back into the system.

I found some crud on the rubber gasket inside the AST cap. I was due for a coolant change anyway, so I flushed the system and cleaned the cap. So far, so good.