Coolant question
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Instructor
Joined: Dec 2001
Posts: 139
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From: Kona Hi
Coolant question
I finally have a question that I havn't been able to find an answer to in the archives. The coolant isn't getting sucked back to the radiator from the recovery/overflow tank after shutdown. When hot, it expands and flows into the tank, but when it starts to cool, there's bubbles/air from the hose in the recovery tank. So after a few times running the car, the coolant level drops in the radiator and keeps filling the tank til it starts sloshing out from the cap. Doesn't get hot and no fluid leaks. Pressure checked the radiator to 15lbs and no leaks, new cap, cleaned tank and new overflow hose, new t-stat. Could this be a clogged core?
Appreciate any thoughts, clues or wild ideas? 75 stock L48
Appreciate any thoughts, clues or wild ideas? 75 stock L48
Racer
Joined: Jan 2002
Posts: 293
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From: carson Missouri
Re: Coolant question (Chevyguy)
My 71 BB was doing the same thing. Not long after that began the heater quit working. A friend told me to disconnect the heater core and flush it. So I took an old garden hose and cut it up and use these long pieces to flush the core. No mess on the car and no boiling and I have heat again.
Racer
Joined: Jan 2001
Posts: 495
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From: ma
Re: Coolant question (Chevyguy)
I had the exact same problem with my wifes car.The radiator was half full while at the same time the coolant recovery tank was over flowing. It was the line from the radiator to the overflow tank it had a pinhole somewhere so the vaccum in the radiator was unable to pull the coolant back in ..it just sucked air in some how.Replace this hose and make sure that its tight.I replaced mine with a clear plastic hose at first and you could see the coolant flow back and forth to verifie that the cap was working as it was supposed to. :cheers: Never did find a leak in the hose..BUT it did cure the problem
Thread Starter
Instructor
Joined: Dec 2001
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From: Kona Hi
Re: Coolant question (Chevyguy)
Thanks guys, I'll try the heater core flush, like the garden hose idea. After the cap, the hose from the radiator to the overflow tank was the first thing I changed, thought there might be a leak, but the pressure is going into the tank instead of pulling the coolant out. :crazy:
Racer
Joined: Jan 2001
Posts: 495
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From: ma
Re: Coolant question (SharkAttack)
When you first shut the car off the coolant will flow in to the tank because of the residual heat in the engine. Once it cools off enough to start to pull a vaccum it will draw from the recovery tank,like sipping a soda through a starw, that hose must have a good conection[alittle permatex on the ends helps] also the leak could be in the molded seam of the tank that the hose connects to.
Thread Starter
Instructor
Joined: Dec 2001
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From: Kona Hi
Re: Coolant question (rdrman)
rdman
Then that could be what's causing the bubbles in the recovery tank, residual heat trying to send coolant to the tank, but the coolant level in the radiator is too low. I've pulled the tank, cleaned and checked it, no leaks, but even if the tank were leaking, as long as the pickup hose inside is below the surface of the coolant it shouldn't suck air, right? Or am I off base here?
Thanks for your help all.
Then that could be what's causing the bubbles in the recovery tank, residual heat trying to send coolant to the tank, but the coolant level in the radiator is too low. I've pulled the tank, cleaned and checked it, no leaks, but even if the tank were leaking, as long as the pickup hose inside is below the surface of the coolant it shouldn't suck air, right? Or am I off base here?
Thanks for your help all.
Racer
Joined: Jan 2001
Posts: 495
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From: ma
Re: Coolant question (Chevyguy)
The bubbles you see are a result of the radiator level being low. If I'm not mistaken your hose connects to the cap? then on the bottom of the cap there is another hose that drops in to the coolant it self? that hose could be the weak link that your looking for. Or the cap it self But If the connection is into a molded portion of the recovery tank,try using some clear nail polish on it to seal it
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Thread Starter
Instructor
Joined: Dec 2001
Posts: 139
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From: Kona Hi
Re: Coolant question (rdrman)
It appears that the nipple on the radiator for the overflow hose had cracked at some point and been soldered. Looking under it with a mirror i can see a couple of pinholes where it would be sucking air. Looks like it's time for a new radiator :rolleyes: Thanks again for everyones help, this sure is a great place :D