Radiator won't hold coolant.
Thread Starter
On The Tree
Joined: Apr 2015
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From: Alabama
Radiator won't hold coolant. I know there are a lot of other threads out there regarding this issue but I've never read one that was specific to my issues. It IS a firebird v6 but all cooling system issues are basically the same be it v8 v6 or God forbid a 4 cylinder. So far it seems the whole cooling system is failing. About a month ago the stat went, it had a small pin hole in it. 3 weeks later the radiator cracked. Now it's the heater core!!
For a week I've been trying to figure this out. After I put my new radiator in. I filled it all up 50/50. It drove amazing for 3 whole days. Then the 4th day it over heated. I let it cool off and drive home and there let it sit for a while. I opened the radiator cap and coolant only half way filled the tank... so I top it off. Next day. Drive it. Does fine the whole drive but when I put it in park, water/coolant starts to come out of the overflow. Just enough to where it empties the radiator to half but never more than that. And I notice that right before it does this the temp goes from 208 (n.o.t) to 212 (boiling point) then after half comes out it goes BACK down to 208 and never overheats again.
So since all it does when I fill it up is blow it out the overflow till it's half way I Was thinking head gasket but I found out from the wet carpet on the pass. Side that my heater cores bad. Would a bad heater core blow coolant/water out of the overflow like that?
Sorry it's such a long post. Just trying to get to the bottom of this mess. Feel free to ask any questions. I'm going next week to get it pressure tested. Any help would be great. Thanks!
For a week I've been trying to figure this out. After I put my new radiator in. I filled it all up 50/50. It drove amazing for 3 whole days. Then the 4th day it over heated. I let it cool off and drive home and there let it sit for a while. I opened the radiator cap and coolant only half way filled the tank... so I top it off. Next day. Drive it. Does fine the whole drive but when I put it in park, water/coolant starts to come out of the overflow. Just enough to where it empties the radiator to half but never more than that. And I notice that right before it does this the temp goes from 208 (n.o.t) to 212 (boiling point) then after half comes out it goes BACK down to 208 and never overheats again.
So since all it does when I fill it up is blow it out the overflow till it's half way I Was thinking head gasket but I found out from the wet carpet on the pass. Side that my heater cores bad. Would a bad heater core blow coolant/water out of the overflow like that?
Sorry it's such a long post. Just trying to get to the bottom of this mess. Feel free to ask any questions. I'm going next week to get it pressure tested. Any help would be great. Thanks!
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by Chevyguy2001
When you refilled it, did you have the front end up on ramps or jacked up??? That's what I did when refilling the radiator. I could be wrong but you have may have air trapped in the system.
My money is on you having the wrong type of radiator cap or a bad radiator cap, which is not:
- pressurizing the system properly
- releasing the vacuum that builds up on cool-down and causes stuff to crack
What kind of cap to you have?
- pressurizing the system properly
- releasing the vacuum that builds up on cool-down and causes stuff to crack
What kind of cap to you have?
this would be my guess as well. Had this problem before on a v6 before I traded it in and the cap didn't exactly work well with the new radiator for some reason.
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by wssix99
My money is on you having the wrong type of radiator cap or a bad radiator cap, which is not:
- pressurizing the system properly
- releasing the vacuum that builds up on cool-down and causes stuff to crack
What kind of cap to you have?
- pressurizing the system properly
- releasing the vacuum that builds up on cool-down and causes stuff to crack
What kind of cap to you have?
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That's a problem.
Yes.
Probably not. A head gasket issue would give you problems 100% of the time.
Yes.
Probably not. A head gasket issue would give you problems 100% of the time.
I got one of those aluminum locking radiator caps. Should I put my old one back on and see what happens? If it doesn't work are we looking at a head or head gasket? It wouldn't seem to be a bad gasket or head cause it's not overheating. It just won't hold the proper amount of coolant.
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If that doesn't work, the 3800 is known for intake gasket leaks and those plastic coolant elbows cracking/breaking. I had a 3800 car I was hard core about before I got my z28.. lol
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by SlasherVRGR
If that doesn't work, the 3800 is known for intake gasket leaks and those plastic coolant elbows cracking/breaking. I had a 3800 car I was hard core about before I got my z28.. lol
Thread Starter
On The Tree
Joined: Apr 2015
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From: Alabama
Okay I put the old cap back on and drove it and it didn't help actually it's stayed at 212 the whole time and actually started smoking and running rough. Waiting to cool down to check the coolant level. Any ideas?
Edit: coolant level went down to half way again. No signs of leaking anywhere except what comes out of overflow. This has me blown away honestly. Why would the car smoke at 212?
Edit: coolant level went down to half way again. No signs of leaking anywhere except what comes out of overflow. This has me blown away honestly. Why would the car smoke at 212?
Last edited by BamaBird22; Feb 5, 2017 at 08:28 PM.
Is this after it has cooled down? If so, this would indicate that you aren't getting a siphon to suck the coolant back from the overflow as things cool and contract. If this is the case, then the cause may be why the system isn't holding pressure. This could be why things are boiling and overflowing. (The system should pressurize, which will raise the boiling point of the fluid in the radiator and keep the fluid in.)
Thread Starter
On The Tree
Joined: Apr 2015
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From: Alabama
Originally Posted by wssix99
Is this after it has cooled down? If so, this would indicate that you aren't getting a siphon to suck the coolant back from the overflow as things cool and contract. If this is the case, then the cause may be why the system isn't holding pressure. This could be why things are boiling and overflowing. (The system should pressurize, which will raise the boiling point of the fluid in the radiator and keep the fluid in.)
212° F is the boiling point of water. If the radiator is boiling over at this temp, it means your cooling circuit is not pressurizing properly. Pressure is what raises the boiling point so that the coolant/water mix stays as a liquid and doesn't turn into a gas (boiling). You can try to run a pressure test on the system when cold. Maybe you will find the leak?
Still/idle issues usually arise from fan problems. Are your radiator fans working?
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
Likes: 1
From: Alabama
Originally Posted by wssix99
Since you aren't in the "red" with regard to temperature also would look to a pressurization issue first.
Still/idle issues usually arise from fan problems. Are your radiator fans working?
Still/idle issues usually arise from fan problems. Are your radiator fans working?
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
Likes: 1
From: Alabama
Been reading a little bit and found that the lt1 radiators have an "extra nipple" that you need to cap off. I didn't know this and I had my wife helping me with this and told her to plug the overflow hose back to the new one. Not sure if she put it in the right spot or not. If I had to guess I would say no. It seems like that bottom nipple would be pressurized which would pressurize the overflow. 
I am more familiar with the LS1 plumbing, but I think this should be universal to ALL radiators: the overflow tank hookup should always be the top-most nipple on the radiator. The radiator cap keeps the pressure from reaching the overflow tank unless it exceeds the limit, and allows vacuum to suck coolant back in when things cool off. If it is plugged in below this, that would create the pressurization problem.