Leaking coolant overflow tank?

TRWeiss1 · 05-21-07, 09:59 AM

Ok, so a little background on what could have potentially led up to this. This past weekend I drove the car up to a meet in Rochester...Car ran fine all the way up there with no problems whatsoever. However, after taking a friend of mine for a ride, I got back to where we were staying and shut the car off. Temps were normal, so I thought nothing of it. But after I popped the hood (just to let it cool down quicker since it was nice out) I heard some hissing coming from the AST (aluminum AST by the way). It then proceeded to drip a small amount of coolant from the AST cap. I quickly surrounded it with some rags, so no coolant would drip/squirt onto anything. It didn't leak much, so I figured it would be fine, and it was....or so I thought. I just took it easy the rest of the meet, and made it back home last night without any problems. Again, as I was driving home the temps were normal. I have a defi water temp gauge, and it never even went above 200 - 210 degrees.

Now, fast forward to this morning when I went to drive the car to work. I get in, start the car, and I'm letting it idle like I usually do for a few minutes before driving. However, about 20 seconds after starting the car the low coolant alarm comes on....Beautiful. Well, I know this is an indication of low coolant in the overflow, so I went to add some and thought I'd be on my merry way. Well, as soon as I added coolant to the overflow I heard it leaking back out onto the floor. Needless to say, I got all of about 2 minutes to investigate this since I was on the verge of leaving for work. I pulled the plastic piece covering the bottom of the overflow out of the way to see if I could see where it was leaking from, but no luck. I just took my civic to work for the day, which is a bummer because it's nice out.

So, I know I've obviously got a leak coming from the overflow, or the overflow line...What I want to know are what are some theories as to what caused this? Could it just be the overflow has been stressed over time and has finally decided to give up from exposure to heat/old age? Or do I have some other gremlin that caused this to fail? I'm not one to just replace a part that broke and call it a day....If at all possible, I want to know what made that part fail. I am wondering if it was at all related to the couple of drops my AST spewed out, or if that was just a coincidence of the AST cap seal going bad.

Any thoughts? Help would be much appreciated.

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Mahjik · 05-21-07, 10:32 AM

A couple of things:

1. When coolant is low, you use the filler neck to fill it:

http://mahjik.homestead.com/files/FD...iller_neck.jpg

The low coolant sensor is near the bottom of the thermostat housing.

2. The overflow tank has a hole near the top to keep the system from overfilling. If you add too much in, it will just expel the excess onto the ground.

3. If the AST cap was leaking, replace the cap.

TRWeiss1 · 05-21-07, 10:48 AM

Ok, thanks a lot Mahjik...That makes me feel a lot better. I was adding coolant to the overflow reservoir, thinking that is what set off the low coolant alarm. The coolant that dripped out the AST cap did need to be topped off, but I was adding coolant to the wrong location.

By the way, I was searching last night and couldn't find anything....Where can I just pick up a new AST cap without buying the whole AST?

Mahjik · 05-21-07, 10:53 AM

Quote:

Originally Posted by TRWeiss1

By the way, I was searching last night and couldn't find anything....Where can I just pick up a new AST cap without buying the whole AST?

Most Autozone, Advanced Auto or NAPA shops carry STANT brand caps. While they are a hit and miss on the quality of the caps, just take your cap with you and they'll match one up.

I've never had a problem with those caps, but some others have in the past.

BillM · 05-21-07, 11:01 AM

I had a similar problem when adding coolant to the overflow bottle. It would just dribble out the bottom. What I found was that the long neck was cracked just above where it connects to the tank. As I added coolant it would just leak out of the crack. Getting it out looks like a bitch so I got some waterproof tape and fixed it that way. So far so good.

TRWeiss1 · 05-21-07, 11:23 AM

^ Gotcha...As far as my problem goes, I believe I just need a new AST cap. There was coolant lost through the cap, and now the alarm is going off. I then overfilled the overflow reservoir thinking the sensor was there, and that would make sense why it overflowed from that location. The car doesn't run that hot, and there is no evidence of milkyness in my oil, so I *hope* it's not a coolant seal. (I know that there won't necessarily be evidence in the oil if a coolant seal is bad, but I checked it anyway). Also, the system doesn't bubble at all while the car is running...In fact, the AST wanted to leak after I shut the car off.

Anyway, I'll take my cap down to the parts store and see if they can match up a new one.

Then, I'll add coolant to the filler neck, start it up, and keep an eye on things.

adictd2b00st · 05-21-07, 12:15 PM

hey whatsup, its jay from buffalo

will was mentioning this to me yesterday, glad to see it was nothing major goodluck!

TRWeiss1 · 05-21-07, 12:57 PM

Hey Jay, how ya doin? Too bad you couldn't make it to the meet...It was a fun time!

Anyway, I went to the house during my lunch break and filled up the coolant properly. Sure enough, the alarm did not go off. I let the car warm up, and sure enough I get a couple drips coming from the AST cap.

I have one dumb question about getting another cap from a parts store...If I get a cap from them, are they going to be able to match one up that contains a spring which opens at 13 psi as this AST cap does? I'd imagine that if I just put a regular cap on there without any pressure spring it would defeat the purpose of the AST...or am I missing something here?

Edit :: Nevermind...found a new cap from mazdatrix.

Mahjik · 05-21-07, 01:03 PM

Quote:

Originally Posted by TRWeiss1

I have one dumb question about getting another cap from a parts store...If I get a cap from them, are they going to be able to match one up that contains a spring which opens at 13 psi as this AST cap does? I'd imagine that if I just put a regular cap on there without any pressure spring it would defeat the purpose of the AST...or am I missing something here?

You mean like this?

http://www.stant.com/brochure.cfm?br...ocation_id=179

TRWeiss1 · 05-21-07, 01:15 PM

Yeah, something like that. :P

So you're saying if I run down to Advance Auto they'll actually have one of these jobbies in stock? (Anymore, doesn't seem like they have anything I need in stock.

)

Mahjik · 05-21-07, 01:25 PM

Quote:

Originally Posted by TRWeiss1

Yeah, something like that. :P

So you're saying if I run down to Advance Auto they'll actually have one of these jobbies in stock? (Anymore, doesn't seem like they have anything I need in stock.

)

Well, what they stock seems to be location dependent. I can say that my local Advanced Auto has them in stock. I would suggest that between them an NAPA, one of them should have one.

TRWeiss1 · 05-21-07, 01:32 PM

Thanks...I'll check those places when I'm out of work.

TRWeiss1 · 05-21-07, 05:18 PM

Thanks for the help guys. I got a new cap at Advance Auto, and it doesn't seem to be leaking. I'll keep a sharp eye on it for a few days, but it appears to be good!

adictd2b00st · 05-21-07, 08:57 PM

yea i was gonna say, i know napa had a 13psi cap the other day when i needed one, not suprised that advance had one for you over there hehe

CantGoStraight · 05-22-07, 05:53 PM

Quote:

Originally Posted by TRWeiss1

Ok, thanks a lot Mahjik...That makes me feel a lot better. I was adding coolant to the overflow reservoir, thinking that is what set off the low coolant alarm. The coolant that dripped out the AST cap did need to be topped off, but I was adding coolant to the wrong location.

By the way, I was searching last night and couldn't find anything....Where can I just pick up a new AST cap without buying the whole AST?

When you saw coolant coming from the AST cap you identified your first problem. This means the system to the recovery tank was open to atmosphere and instead of drawing coolant back from the tank it was pulling air, (not good as it lowers the ability of the cooling system to maintain the proper level) coolant goses out ,doesn't come back in and when replaced with air can cause localized hot spots with in the motor and lowers the boiling point and ability to keep the car from boiling. Your cap depending on the brand of AST will take a domestic cap or an import cap and is found at most any auto parts store. As for your recovery tank there is a full mark on the little dipstick and a low mark, both of these marks are to be checked when the systm is cold and should be filled to the full mark when cold. When checked hot it should be some where above the full mark and it should never fall below the low mark when cold or it will draw back air instead of coolant.

The Black Seven · 06-03-07, 03:39 AM

[quote=Mahjik;6961815]A couple of things:

2. The overflow tank has a hole near the top to keep the system from overfilling. If you add too much in, it will just expel the excess onto the ground.

I'm having the similiar situation when I fill the overflow tank and it just leaks out...however, the leak is coming out between the neck of the bottle. Where the black rubber piece is at. Is this where you are talking about?? To me, it looks like the rubber piece is brittle...Please advise!!! Thanks.

CantGoStraight · 06-03-07, 01:15 PM

QUOTE=Mahjik;6961815]A couple of things:

2. The overflow tank has a hole near the top to keep the system from overfilling. If you add too much in, it will just expel the excess onto the ground.

Quote:

Originally Posted by The Black Seven

[I'm having the similiar situation when I fill the overflow tank and it just leaks out...however, the leak is coming out between the neck of the bottle. Where the black rubber piece is at. Is this where you are talking about?? To me, it looks like the rubber piece is brittle...Please advise!!! Thanks.

The recovery tank has a dipstick in it. The levels indicated (FULL) and (LOW) are readings taken when the engine (cooling system) IS COLD. If it's coming out where the neck joins the tank I'd say your WAY THE HELL above the full mark.