1977 C3 overflow tank question
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
1977 C3 overflow tank question
I thought my overflow tank was leaking so I pulled it. I filled it with water and capped the top hole and put air pressure into inlet by neck. No leaks. My radiator overflow hose connects to the small inlet next to
The overflow tank neck. What is the molded hole line on top of the tank for? It looks like it could connect to something? Is it a relief? I think that top mounded hole is why my overflow never holds antifreeze and why the radiatior is where it is. I looked in the assembly manual and it shows a hose from radiator to a 2 hole type cap on overflow tank to top of overflow tank and one hose leading off of the overflow tank like an overflow leader. But I have a plain cap, the molded hole on top overflow goes to tank top and the one next to tank neck goes to overflow tank bottom. Bubba put a hose from radiator neck overflow tube to overflow tank hole by neck that goes to overflow bottom. I would like this correct on my car. Can someone tell me how theirs is? Help!
Thanks
Jax
1977 L-82
The overflow tank neck. What is the molded hole line on top of the tank for? It looks like it could connect to something? Is it a relief? I think that top mounded hole is why my overflow never holds antifreeze and why the radiatior is where it is. I looked in the assembly manual and it shows a hose from radiator to a 2 hole type cap on overflow tank to top of overflow tank and one hose leading off of the overflow tank like an overflow leader. But I have a plain cap, the molded hole on top overflow goes to tank top and the one next to tank neck goes to overflow tank bottom. Bubba put a hose from radiator neck overflow tube to overflow tank hole by neck that goes to overflow bottom. I would like this correct on my car. Can someone tell me how theirs is? Help!
Thanks
Jax
1977 L-82
Last edited by xkeots; Jul 6, 2016 at 08:01 PM. Reason: Spelling/correction
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Posting a photo of yours would help.
I do know that there are two designs,
The first design has a cap that has two ports on it so one goes to the radiator area and the other is for overflow. The later design...the overflow comes out the cap if I am not mistaken.
So I am a bit confused by what you are describing.
DUB
I do know that there are two designs,
The first design has a cap that has two ports on it so one goes to the radiator area and the other is for overflow. The later design...the overflow comes out the cap if I am not mistaken.
So I am a bit confused by what you are describing.
DUB
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Posting a photo of yours would help.
I do know that there are two designs,
The first design has a cap that has two ports on it so one goes to the radiator area and the other is for overflow. The later design...the overflow comes out the cap if I am not mistaken.
So I am a bit confused by what you are describing.
DUB
I do know that there are two designs,
The first design has a cap that has two ports on it so one goes to the radiator area and the other is for overflow. The later design...the overflow comes out the cap if I am not mistaken.
So I am a bit confused by what you are describing.
DUB
How are you? How have you been? How is N Carolina treating ya? Shop busy?
How do I post a picture here?
I have the overflow tank with a molded tube on the tank top a single cap and next to cap is a tube with a copper colored metal inside the tube. Bubba connected the radiator overflow to that.
Thanks
Jax
PS: same car I have been building piece by piece In between other cars to change the pace. Finally almost done after all these years. Has always been drive able.
Last edited by xkeots; Jul 6, 2016 at 08:56 PM. Reason: Explanation
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
It has been like that, I pressure checked the overflow tank and no leaks. I keep loosing anti freeze. If the overflow stays empty and radiator full it stays like that. But if I fill to line on overflow the anti freeze leaves the tank. I am stumped.
I just spent the day doing a system clean back and forth. Water was clear.
Jax
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Thanks DUB!
It has been like that, I pressure checked the overflow tank and no leaks. I keep loosing anti freeze. If the overflow stays empty and radiator full it stays like that. But if I fill to line on overflow the anti freeze leaves the tank. I am stumped.
I just spent the day doing a system clean back and forth. Water was clear.
Jax
It has been like that, I pressure checked the overflow tank and no leaks. I keep loosing anti freeze. If the overflow stays empty and radiator full it stays like that. But if I fill to line on overflow the anti freeze leaves the tank. I am stumped.
I just spent the day doing a system clean back and forth. Water was clear.
Jax
In the fall I may get out there with my coolant pressure tester and soap water and mist down all connections and see if I see bubbles anywhere.
Way I look at it..it gives me a reason to raise the hood weekly and do inspections on stuff.
DUB
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
My pick up truck does the same thing. I know the coolant system holds pressure when I test it and it does not leak coolant anywhere....and when I add coolant in the overflow tank...in time.... it is gone....and I know that the hose from the radiator to the overflow tank is good and connections are tight.....and I honestly do not give it a thought. My truck does not run hot..I am not leavign coolant on the ground..and it is my truck and I really do not give crap to spend time trying to figure out this puzzle...at this time...when it is HOT as heck here.
In the fall I may get out there with my coolant pressure tester and soap water and mist down all connections and see if I see bubbles anywhere.
Way I look at it..it gives me a reason to raise the hood weekly and do inspections on stuff.
DUB
In the fall I may get out there with my coolant pressure tester and soap water and mist down all connections and see if I see bubbles anywhere.
Way I look at it..it gives me a reason to raise the hood weekly and do inspections on stuff.
DUB
Thanks
Jack
Last edited by xkeots; Jul 9, 2016 at 12:42 PM. Reason: Omitted word
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
I am trying to follow what you wrote.
if you put coolant mix in the overflow tank to about half way...and KNOWING that the hose is good and the tank does not leak.
When you go and drive it...and get it to 190 degrees Fahrenheit....and come home and pop the hood and there is NO coolant mix in the tank...something is wrong for sure.
i assume that you have a 15psi CLOSED SYSTEM radiator cap on our radiator also.
Because...if anything...the radiator should puke coolant into the tank and not suck it in because the system is hot and under pressure. The coolant mix will get drawn back into the radiator when teh system cools down...which is why the hose form the radiator to the over flow tank is good.
DUB
if you put coolant mix in the overflow tank to about half way...and KNOWING that the hose is good and the tank does not leak.
When you go and drive it...and get it to 190 degrees Fahrenheit....and come home and pop the hood and there is NO coolant mix in the tank...something is wrong for sure.
i assume that you have a 15psi CLOSED SYSTEM radiator cap on our radiator also.
Because...if anything...the radiator should puke coolant into the tank and not suck it in because the system is hot and under pressure. The coolant mix will get drawn back into the radiator when teh system cools down...which is why the hose form the radiator to the over flow tank is good.
DUB
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
I am trying to follow what you wrote.
if you put coolant mix in the overflow tank to about half way...and KNOWING that the hose is good and the tank does not leak.
When you go and drive it...and get it to 190 degrees Fahrenheit....and come home and pop the hood and there is NO coolant mix in the tank...something is wrong for sure.
i assume that you have a 15psi CLOSED SYSTEM radiator cap on our radiator also.
Because...if anything...the radiator should puke coolant into the tank and not suck it in because the system is hot and under pressure. The coolant mix will get drawn back into the radiator when teh system cools down...which is why the hose form the radiator to the over flow tank is good.
DUB
if you put coolant mix in the overflow tank to about half way...and KNOWING that the hose is good and the tank does not leak.
When you go and drive it...and get it to 190 degrees Fahrenheit....and come home and pop the hood and there is NO coolant mix in the tank...something is wrong for sure.
i assume that you have a 15psi CLOSED SYSTEM radiator cap on our radiator also.
Because...if anything...the radiator should puke coolant into the tank and not suck it in because the system is hot and under pressure. The coolant mix will get drawn back into the radiator when teh system cools down...which is why the hose form the radiator to the over flow tank is good.
DUB
Last edited by xkeots; Jul 10, 2016 at 12:13 PM.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Try this...just for the heck of it.
Using 2 liter bottle of soda that is empty...strap it in the car...put water in it and stick the hose from the radiator in it and drive the car and see what happens.
Are you using ONLY water??? or are you actually putting a 50/50 mix in the overflow.???
If this is too much of a hassle..I understand.
MAKE SURE that your radiator cap is a CLOSED SYSTEM CAP. I would assume that it is..but I have to ask to make sure.
DUB
Using 2 liter bottle of soda that is empty...strap it in the car...put water in it and stick the hose from the radiator in it and drive the car and see what happens.
Are you using ONLY water??? or are you actually putting a 50/50 mix in the overflow.???
If this is too much of a hassle..I understand.
MAKE SURE that your radiator cap is a CLOSED SYSTEM CAP. I would assume that it is..but I have to ask to make sure.
DUB
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Try this...just for the heck of it.
Using 2 liter bottle of soda that is empty...strap it in the car...put water in it and stick the hose from the radiator in it and drive the car and see what happens.
Are you using ONLY water??? or are you actually putting a 50/50 mix in the overflow.???
If this is too much of a hassle..I understand.
MAKE SURE that your radiator cap is a CLOSED SYSTEM CAP. I would assume that it is..but I have to ask to make sure.
DUB
Using 2 liter bottle of soda that is empty...strap it in the car...put water in it and stick the hose from the radiator in it and drive the car and see what happens.
Are you using ONLY water??? or are you actually putting a 50/50 mix in the overflow.???
If this is too much of a hassle..I understand.
MAKE SURE that your radiator cap is a CLOSED SYSTEM CAP. I would assume that it is..but I have to ask to make sure.
DUB
You should know me better. After the flushing it must be 60 green/40 water with a new 16lb closed cap.
Thanx
Jax
77 L-82
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
No leaks. The fluid stays to the top of radiator and doesn't go down from there. If I fill overflow to full it empties but radiator always stays full. No leaks in overflow tank or hose connecting the two. I am stumped. Compression and leak down fine, head gaskets nonissue.
Jax
77 L-82
Jax
77 L-82
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
No leaks. The fluid stays to the top of radiator and doesn't go down from there. If I fill overflow to full it empties but radiator always stays full. No leaks in overflow tank or hose connecting the two. I am stumped. Compression and leak down fine, head gaskets nonissue.
Jax
77 L-82
Jax
77 L-82
Thanks
Jax
1977 L-82