[Carmine]

Hi everyone. I thought some of this was behind me, but not quite yet. Went for a ride in my '71 GTO a few days ago, and all went well. It was warmer then today and the temp. stayed pretty much at about 190-195. Brought the car home and nothing on the floor over night. Today, took the car out again for a ride which lasted about 40 minutes and we stopped to get some ice cream. While looking at the car from a short distance, saw something leaking out the passenger side front. Took a quick look and saw that it was puking out antifreeze through the over flow hose. I didn't think there was anything I could do about it except watch and get disgusted. I would guess it puked out about 1 quart; no more then that. Prior to shutting it off for ice cream, it was running real well. Temp. stayed at about 190. Not over heating at all. Any idea why something like that happened or what I should be looking at?? I previously checked the radiator and it was quite full. Not sure how that happened because I like to keep it down about 1" or so from the top. Is it possible that there was too much in it and after getting hot, it seeks its own level?? This happened after only sitting a few minutes after shutting it off. Thanks for any suggestions, Carmine.

[Bluesugar]

I would consider an over-flow coolant tank to capture pressurized leakage,(that's why
the auto manufacturers started installing same) however be sure you have the proper working PSI radiator cap

[Carmine]

Originally Posted by Bluesugar

I would consider an over-flow coolant tank to capture pressurized leakage,(that's why
the auto manufacturers started installing same) however be sure you have the proper working PSI radiator cap

Thanks for your reply and I can certainly buy and install an overflow tank. The radiator cap is rated at 15lbs and brand new but that doesn't mean it can't be defective. Any idea why it does it though?? Thanks, Carmine.

[Bluesugar]

Well it could have a wrong or defective thermostat,some minds will drill holes
around the perimeter of said item or just leave it out altogether to gain knowledge
of water temps and its results

[fyrffytr1]

I know this is basic and don't mean to insult you or anything like that but you aren't filling the radiator all the way up are you? There should be about a 1" void from the top of the tank to the coolant level. I always go by the one finger joint method of measuring when the coolant is cold. I stick my finger in the radiator and should be able to go to the first joint before touching the coolant.

[ZeGermanHam]

Since the radiator was very full (i.e., overfilled) as you described, I think this is simply a case of the coolant expanding when hot and it simply had nowhere to go other than out the overflow hose. It probably won't do it again now that it has purged some coolant and is likely down to a more reasonable level.

[Goatracer1]

If you look at the side of the radiator tank you should see a full mark there. Do not over fill the radiator or it will continue to overflow. Pressure test the cap and make sure there is no obstruction in the fill neck to keep the cap from sealing. If the radiator is filled correctly you should not need an overflow tank. The only reason newer cars have them is so the factory could make the tanks smaller.

[Carmine]

Originally Posted by fyrffytr1

I know this is basic and don't mean to insult you or anything like that but you aren't filling the radiator all the way up are you? There should be about a 1" void from the top of the tank to the coolant level. I always go by the one finger joint method of measuring when the coolant is cold. I stick my finger in the radiator and should be able to go to the first joint before touching the coolant.

Yes, it was quite full. Not sure how this happened exactly because I'm the only one who works on this car. So, it has to be my fault. I usually like to leave some space at the top, but when I looked prior to this last issue, the radiator liquid was almost to the lip of where the radiator cap fits. A few more drops and it would have run out. Since submitting this thread, I've given this issue some additional thought. I recalled some time ago having and identical issue with my '62 409. Someone on another forum mentioned too much fluid in the radiator. Filled too high. They said that it will seek it's own level and puke out the rest. Not to fill it even if it looks low. So, I didn't and it runs all day at 180 degrees. I looked it the tank and it's about 1.5" below the top. I'm going to check the fluid level this morning and I think it's best for now to leave it as is. I'm certainly going to monitor it. Thank you everyone for your responses. I do appreciate it, Carmine.

[Carmine]

Just checked the fluid level. It seems to be down about 3", but no more then that. With the cap off, going to idle it until it reaches operating temp., thermostat opens, and I can see the water circulating. Just want to see what it does. Would anyone know if a '71 came from the factory with an overflow tank?? Thanks, Carmine.

[72LuxuryLeMansLa.]

The '72 Service manual says to fill the radiator to a level 3" below the filler neck. Could be the cooling system wants that extra space......

[Carmine]

Originally Posted by 72LuxuryLeMansLa.

The '72 Service manual says to fill the radiator to a level 3" below the filler neck. Could be the cooling system wants that extra space......

Thank you for sharing that little tidbit of info. I think you and others are correct who mentioned it. I never knew that. I always filled them to the top, but will be changing my ways, Carmine.

[sts]

I knew the number, I just wanted to quote it from the book.

69 Service Manual, pg 6A-3. All cold radiators are full 3” below the filler neck. Pretty sure it's across the board for all Pontiac radiators.

I used my hard copy because the never-ending one-page pdf is miserable to use, but it's the only free 69 I've found, and it's better than nothing. If someone has a better format, please share with the board.

http://pontiac.netbro.de/new_media/f...ice_manual.pdf


Much nicer format
The 67
http://thefirstgensite.com/html/P67svcmanual.htm


The 68
http://thefirstgensite.com/html/68smi.html

This site does update, not an overflow of new-old manuals, but I have seen a new-old manual or two since I found the site. Might want to snatch this collection of free service manuals, dead links on the advertisements.

http://www.oldcarmanualproject.com/


Most guys consider puke bottles mandatory. Between the cold fill on the puke bottle, and the packed-to-the-cap radiator, it increases the cooling capacity, possibly, up to a half gallon. Lots of owners are bears about “correct,” but this is one modification that the majority uses. Our cars are supposed to look cool. As you know, there is nothing cool-looking about your car puking in the parking lot.