coolant overflow tank question
Thread Starter
Racer
Joined: Jan 2006
Posts: 304
Likes: 0
From: Plymouth Meeting PA
coolant overflow tank question
Well, I have been working on my 1970 convertible to get it roadworthy and I have yet another question. When I take the cap off of the reservoir/overflow tank and hit the gas the coolant bubbles out. Is this normal or is there a problem? Also, how do I drain the old coolant to put in fresh coolant? Any and all help would be appreciated.
Thanks,
Tony
Thanks,
Tony
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
You may have a bad radiator cap, allowing the coolant out of the radiator at too low a pressure. You can have it checked at Auto Zone or just buy a new one.
If you can't find a petcock, take off the lower radiator hose to drain the coolant.
If you can't find a petcock, take off the lower radiator hose to drain the coolant.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Originally Posted by Clint's C3
You may have a bad radiator cap, allowing the coolant out of the radiator at too low a pressure. You can have it checked at Auto Zone or just buy a new one.
If you can't find a petcock, take off the lower radiator hose to drain the coolant.
If you can't find a petcock, take off the lower radiator hose to drain the coolant.
His should have exp tank which is diff than a overflow tank, the expansion tank has the rad cap on it and the rad is connected via a hose so when you rev it it is like reving a newer rad with the rad cap off, fluid will well up and out of the neck
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by tonyro
Well, I have been working on my 1970 convertible to get it roadworthy and I have yet another question. When I take the cap off of the reservoir/overflow tank and hit the gas the coolant bubbles out. Is this normal or is there a problem? Also, how do I drain the old coolant to put in fresh coolant? Any and all help would be appreciated.
Thanks,
Tony
Thanks,
Tony
Last edited by ...Roger...; Jun 20, 2006 at 07:13 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Instructor
Joined: Apr 2006
Posts: 147
Likes: 0
From: New Jersey
Originally Posted by tonyro
When I take the cap off of the reservoir/overflow tank and hit the gas the coolant bubbles out. Is this normal or is there a problem?
Also, how do I drain the old coolant to put in fresh coolant?
Also, how do I drain the old coolant to put in fresh coolant?
Having coolant bubble out with the cap off when you hit the gas, does not sound normal to me.
Are you sure that you have not over-filled the radiator?
Are there markings on your radiator that indicate how high to fill?
I know that on a 69' Corvette with automatic transmission and air conditioning, there is no overflow tank. And in that case you are only to fill the radiator to the marking on the radiator; about an inch and a half from the top.
I am not sure what the requirements are for cars with an expansion tank.
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Originally Posted by Fevre
His should have exp tank which is diff than a overflow tank, the expansion tank has the rad cap on it and the rad is connected via a hose so when you rev it it is like reving a newer rad with the rad cap off, fluid will well up and out of the neck
OK, my bad. I have an 82 with an overflow tank.
Thread Starter
Racer
Joined: Jan 2006
Posts: 304
Likes: 0
From: Plymouth Meeting PA
thanks for the responses. I only ttt to get different opinions. I have the expansion tank and the cap is on it. When I hit the gas it flows out the neck. Fevre, I guess this is ok
Thanks
Tony
Thanks
Tony
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by Mike Ward
The first answer you got to your questions was correct, why do you keep ttt?
Racer
Joined: Nov 2004
Posts: 432
Likes: 0
From: Granbury TX
Originally Posted by tonyro
thanks for the responses. I only ttt to get different opinions. I have the expansion tank and the cap is on it. When I hit the gas it flows out the neck. Fevre, I guess this is ok
Thanks
Tony
Thanks
Tony
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
It's an "expansion tank". In order for it to work there must be some place/space for the fluid to "expand" into since a fluid cannot be compressed. Therefore, the "expansion tank" should only be filled half full (there is a cold fill line on some tanks). When properly filled (half full) you should get no flow/bubbling out of coolant when you rev the motor nor when the motor comes up to operating temp.
You can drain the system via the petcock valve on the radiator or simply remove one end of the lower radiator hose if you're in a hurry.
You can drain the system via the petcock valve on the radiator or simply remove one end of the lower radiator hose if you're in a hurry.
