Some cooling system questions
Thread Starter
Junior Member
Joined: Apr 2011
Posts: 2
From: Alberta
Hey guys, been having some troubles with my cooling system and have a few questions before I take action.
The current issue originated about a week ago. Pulled into town, and noticed a coolant leak. Popped the hood, the hose attached to the filler neck had a crack and was leaking. I immediately brought the car to the garage, and shut it off. Simple fix, replace probably what was the easiest hose in the system to replace. But when I topped off the system, I think then it started behaving weird. Generally, when burping the system or filling it, I fill the AST first and then finish of with the filler neck. However, the AST didn't retain coolant that well. You would fill it up and the level would decrease. (Obvious statement here is cracked AST. I've checked and the is no coolant around the tank other than maybe a tiny bit of spillage. Even after that dried though, nothing more.) I filled that up quite a bit before I gave up, capped it and went to the filler neck. When I'm filling, I should mention I had the TB line disconnected as recommended. There was no coolant coming out the end when filling it up, ie it was held up high enough. Looking at the coolant flow diagram, (I'm sure you know what I'm talking about,) I've came to the consensus that the coolant was exiting through the bottom AST hose which leads to the rad. This means the coolant found it's way into the coolant system and not onto the ground. However, I got fed up with filling that so i topped it off one last time, and capped it. Pretty sure it the level was going down. I should mention the filler neck cap was also off during this process. After it was capped, I moved over and filled the filler neck. First time I filled it up, it retained coolant. Capped it and called it a day. What I regret not doing was checking the AST after that, (remove cap and see if level went down.)
I understand that this could very well just have occured because the system just wasn't full and it kept taking more and more coolant. Could it have just been a coincidence that when I moved to the filler neck, that's when it was finally full?
After that, I made the decision, (foolish decision?) to drive it. First I drove around the block, it reached full operating temp, then took it back to my place and with it running, did a quick inspection and didn't find any signs of leakage. So I drove more, eventually came to a destination, turned it off, did my thing, then come back out side, moved the car so I could see any leaks on the ground. Sure enough, some coolant had found it's way out. Not much I'd hesitate to even say half an ounce. There was nothing I could do there so I drove it home, and parked in the garage, opened the hood and let it cool. When I came back out after maybe 45 minutes, there was more coolant on the floor. I would say maybe a full cup had fallen and flowed to the back of the garage. After inspecting, the leak seemed to be from the overflow. Whether it overflowed, cracked, or even a line around it buggered out I'm not entirely sure but I would say either it overflowed or cracked.
Now, lets assume this leak occurs after shut off. (Make that assumption because it didn't seem to leak, at least nothing I could visually see, while it was running, and the longer it was parked, the more coolant was found on the ground.) There are threads all over the Internet about leaks, even overflows after shutoff. Half the people will jump out and say coolant seal, some will say replace caps, some will say replace rad, heater core, all lines etc etc.. And in different cases, most of these have proven to be the cause. The point is, the cause at this point could be absolutely ANYTHING relating to the cooling system. So I'm going to spread out some details that I would find important to my specific situation so maybe you guys could share some light. (Assuming this issue isn't coolant seal failure, I am tearing the whole cooling system apart and redoing it. This is my third leak in about 2 weeks and it's driving me crazy.)
First question: Lets assume it's coolant seal failure. I don't understand why it would ONLY leak upon shut off? Also, they say the reason for the overflow in general happens, (not specifically at shut off) is because the nature vacuum won't occur when the coolant contracts and it won't be sucked back out of the overflow tank so it fill fill up, expand and spill. Makes perfect sense. But ANY coolant leak would cause that. Anyways, why just on shut off?
Next: After letting it completely cool off, i removed the filler neck cap first, then the AST cap. I should note that the ast level wasn't decreasing like I stated 4 chapters ago. The level of the coolant was good. It obviously needed a little coolant since it's in the burping process but the amount leaked seems like it doesn't explain this loss. Hard to explain. I would love to fully burp the system, ie, drive it to operating temp about 3 or 4 more times, let it cool down after each, and top up filler neck level, and ast if low enough. The first time I burped, the amount the level decreased is very similar to what I have not. I am scared to drive it though. In question form: assuming the water seals were bad, would the level of coolant in the pressurized part of the system continually decrease as well prompting to constantly have to top off?
Another general question about the champagne bubble test. WHY?
Why is this test used. In my opinion, ANY amount of air in the system will cause this. If give a bit of throttle, and bubbles react corresponding to the throttle, then you could conclude coolant jacket failure but for me, I know 100% I would fail that test because my system isn't 100% free of air. I get the reasoning behind it but any amount of air would cause the same effect.
Thank you for those of you who read my novel. Help is appreciated. I generally like to think critically about the issue then take action and see if it works, (Has twice so far) but I'm at a loss right now. Thanks everyone,
Mitch
The current issue originated about a week ago. Pulled into town, and noticed a coolant leak. Popped the hood, the hose attached to the filler neck had a crack and was leaking. I immediately brought the car to the garage, and shut it off. Simple fix, replace probably what was the easiest hose in the system to replace. But when I topped off the system, I think then it started behaving weird. Generally, when burping the system or filling it, I fill the AST first and then finish of with the filler neck. However, the AST didn't retain coolant that well. You would fill it up and the level would decrease. (Obvious statement here is cracked AST. I've checked and the is no coolant around the tank other than maybe a tiny bit of spillage. Even after that dried though, nothing more.) I filled that up quite a bit before I gave up, capped it and went to the filler neck. When I'm filling, I should mention I had the TB line disconnected as recommended. There was no coolant coming out the end when filling it up, ie it was held up high enough. Looking at the coolant flow diagram, (I'm sure you know what I'm talking about,) I've came to the consensus that the coolant was exiting through the bottom AST hose which leads to the rad. This means the coolant found it's way into the coolant system and not onto the ground. However, I got fed up with filling that so i topped it off one last time, and capped it. Pretty sure it the level was going down. I should mention the filler neck cap was also off during this process. After it was capped, I moved over and filled the filler neck. First time I filled it up, it retained coolant. Capped it and called it a day. What I regret not doing was checking the AST after that, (remove cap and see if level went down.)
I understand that this could very well just have occured because the system just wasn't full and it kept taking more and more coolant. Could it have just been a coincidence that when I moved to the filler neck, that's when it was finally full?
After that, I made the decision, (foolish decision?) to drive it. First I drove around the block, it reached full operating temp, then took it back to my place and with it running, did a quick inspection and didn't find any signs of leakage. So I drove more, eventually came to a destination, turned it off, did my thing, then come back out side, moved the car so I could see any leaks on the ground. Sure enough, some coolant had found it's way out. Not much I'd hesitate to even say half an ounce. There was nothing I could do there so I drove it home, and parked in the garage, opened the hood and let it cool. When I came back out after maybe 45 minutes, there was more coolant on the floor. I would say maybe a full cup had fallen and flowed to the back of the garage. After inspecting, the leak seemed to be from the overflow. Whether it overflowed, cracked, or even a line around it buggered out I'm not entirely sure but I would say either it overflowed or cracked.
Now, lets assume this leak occurs after shut off. (Make that assumption because it didn't seem to leak, at least nothing I could visually see, while it was running, and the longer it was parked, the more coolant was found on the ground.) There are threads all over the Internet about leaks, even overflows after shutoff. Half the people will jump out and say coolant seal, some will say replace caps, some will say replace rad, heater core, all lines etc etc.. And in different cases, most of these have proven to be the cause. The point is, the cause at this point could be absolutely ANYTHING relating to the cooling system. So I'm going to spread out some details that I would find important to my specific situation so maybe you guys could share some light. (Assuming this issue isn't coolant seal failure, I am tearing the whole cooling system apart and redoing it. This is my third leak in about 2 weeks and it's driving me crazy.)
First question: Lets assume it's coolant seal failure. I don't understand why it would ONLY leak upon shut off? Also, they say the reason for the overflow in general happens, (not specifically at shut off) is because the nature vacuum won't occur when the coolant contracts and it won't be sucked back out of the overflow tank so it fill fill up, expand and spill. Makes perfect sense. But ANY coolant leak would cause that. Anyways, why just on shut off?
Next: After letting it completely cool off, i removed the filler neck cap first, then the AST cap. I should note that the ast level wasn't decreasing like I stated 4 chapters ago. The level of the coolant was good. It obviously needed a little coolant since it's in the burping process but the amount leaked seems like it doesn't explain this loss. Hard to explain. I would love to fully burp the system, ie, drive it to operating temp about 3 or 4 more times, let it cool down after each, and top up filler neck level, and ast if low enough. The first time I burped, the amount the level decreased is very similar to what I have not. I am scared to drive it though. In question form: assuming the water seals were bad, would the level of coolant in the pressurized part of the system continually decrease as well prompting to constantly have to top off?
Another general question about the champagne bubble test. WHY?
Why is this test used. In my opinion, ANY amount of air in the system will cause this. If give a bit of throttle, and bubbles react corresponding to the throttle, then you could conclude coolant jacket failure but for me, I know 100% I would fail that test because my system isn't 100% free of air. I get the reasoning behind it but any amount of air would cause the same effect.
Thank you for those of you who read my novel. Help is appreciated. I generally like to think critically about the issue then take action and see if it works, (Has twice so far) but I'm at a loss right now. Thanks everyone,
Mitch
Senior Member
Joined: Nov 2009
Posts: 1,833
From: peru, IN
Unless you have sweet smelling exhaust smoke i wouldnt jump to the conclusion of a coolant seal failure. The best thing is always to get underneath the car and trace back the leak. Common leaks I see are lines cracking or clamps going bad, or a good ol water pump. Always eliminate the simple things first then start digging deeper.
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