Whole lotta pressure... what gives?

krash kendall

Active Member

Nov 19, 2004

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Aldergrove, B.C. Canada

May 24, 2005

#21

• May 24, 2005

• #21

Cap is pretty much what you described CC. By the way, I know with my '65 that bypassing the heater results in a hot car due to the loss of coolant volume. I treat my heater core as a second radiator and I don't believe the '67 rad is very much larger.

 

Pakrat

Founding Member

Aug 6, 2000

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Currently: NH Originally: Rhode Island (and all po

May 24, 2005

#22

• May 24, 2005

• #22

After reading all of this it seems you already have good advice, there is little I can add.

Your mix is not your problem as said, but you should get back to 50/50 ASAP to avoid corrosion. (Plain ole H2O does work the best though for cooling)

Is it possible that you are overfilling the car? This is the most common cause of puking, not so much backpressure, but for what it is worth you should only fill it to the top row, not the top itself.

I had the in line flush tee on the heater hose as well, I just hid it under the air cleaner. When refilling your car if you leave that cap off until you see coolant start to flow from it and then cap it and continue to fill, you will insure that very little if any air gets into the system. (without one leave the top hose off until you see coolant start flow)

The factory gauge is just a reference, without numbers you can't really verify that your thermostat is working properly. You can check it on your stove though.

You really should put a fan shroud back on. Not only does it help protect the hose, but without it your fan is really just blowing the warm air in the compartment around. The shroud makes sure the fan draws the outside coller air through the radiator though thus aiding in cooling.

Does your bottom hose have the support spring in it? If not even though it worked fine before it could randomly collapse without a spring and this could be a possible way that air is entering in if the radiator is trying to pull water through a closed hose.

The lack of a heater system is not the problem, I dumped mine years ago. I even went so far as to run one long hose in and out of my firewall so it still looks stock. I hate to see it replaced with a little bypass hose instead.

 

CornerCarvin67

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Dec 30, 2004

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May 25, 2005

#23

• May 25, 2005

• #23

Well hopefully I'll get a chance to put all this good advice to test tonight. I'd like to have this all figured out soon because my Spal should be here any day. I don't want to add another factor to the equation.

 

CornerCarvin67

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Dec 30, 2004

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Jun 13, 2005

#24

• Jun 13, 2005

• #24

Okay... here's an update.

I blew out my lower radiator hose last week going down the road also!! Great fun, hey??

So after much conversation with many people... today I decided to call Summit for a little tech advice. What educated me on was that there is a difference between a recovery resevoir and an overflow tank. I have the overflow tank. The problem he said lies in that I have a radiator cap for a closed system that utilizes the recovery resevoir method. That radiator cap is called a "closed cap". What he said I needed was an "open cap". This cap will allow the air pressure to bleed off thru the cap. The tank I have is strictly for overflow fluid. It's NOT intended to return the fluid.

Now it all makes sense. I'm not going to debate which system works better for a car.... but it's nice to finally know. Shoot, with two new hoses on the system... who knows what would have blown up next??!!

I will get an open cap tonight hopefully and put this issue to bed this week...

 

84convertablegt

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Nov 6, 2004

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Columbus, OH

Jun 13, 2005

#25

• Jun 13, 2005

• #25

my question is how do you know the difference between an open cap and a closed one? i have a recovery reservoir that works but i have never used a special cap except for that its a 16lb. one instead of a 13lb. one. by the way, a 16lb cap will raise your boiling point which helps keep you from boiling over and is still pretty safe for our systems

 

CornerCarvin67

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Dec 30, 2004

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Jun 13, 2005

#26

• Jun 13, 2005

• #26

Good question... I don't know. I'm hoping to get one tonight and notice an obvious physical difference. Cross my fingers.

84convertablegt said:

my question is how do you know the difference between an open cap and a closed one? i have a recovery reservoir that works but i have never used a special cap except for that its a 16lb. one instead of a 13lb. one. by the way, a 16lb cap will raise your boiling point which helps keep you from boiling over and is still pretty safe for our systems

Click to expand...

 

CornerCarvin67

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Dec 30, 2004

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Jun 13, 2005

#27

• Jun 13, 2005

• #27

Well this is just crazy. I can't believe this is such difficult issue. The guy at the Advance Auto Part store (older gentleman) said he's never heard of an "open" system radiator cap. And if you look on the shelf... they really all do look the same except for size. He believes... like I've also read in here... that there is just too much fluid in the system. When it gets hot and expands it creates all the pressure I'm seeing. He said the radiator cap (13lbs psi) should simply allow that pressured air to relieve itself thru the cap. Okay, fine. But at what point does the water go to my overflow tank and not thru the cap itself? Should there be some kind of pressure relief hole on the overflow tank? I didn't have any of these problems when I just had the water bottle duct taped to the hose off the radiator neck (I had to because I laid some fluid on the course during an autocross run). It was a temp fix to get me thru the day. It was by no means a tight seal at all. I'm imaging both the expanded water and the high pressure released into that bottle with no problems. Now with a sealed tank on there... it's giving me all this pressure back up. The thing that I can't really attest to is the level of fluid in the system during these different times. Maybe before I had the right amount of fluid.... and then later I managed to overfill it and create this problem. I'm so tired of this one. I'm ready to just leave the valve on the bottom of the tank open all the time and just close it during race runs to keep it from peeing on the course. I'm done with this.

 

65ShelbyClone

Founding Member

Sep 9, 2000

4,675

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119

Antelope Valley, SoCal

Jun 13, 2005

#28

• Jun 13, 2005

• #28

Well, I've never heard of an "open" or "closed" cooling system either. I"ve never seen a difference in caps to indicate that a difference even exists.

There is only one difference I can think of between an expansion tank and an overflow; the expansion tank has the inlet on the bottom so the radiator can suck up the extra coolant when everything cools down. An overflow just catches it for you to empty later. Even if you DO have too much coolant, it should just overflow into the catch can and never exceed the cap's rated pressure. Likewise, just about all caps you can get at the parts store should allow for coolant recovery.

 

Edbert

Founding Member

Jul 13, 2002

3,548

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109

Austin TX

Jun 13, 2005

#29

• Jun 13, 2005

• #29

Not much to add here, but I have also heard of the two different systems (open vs closed) before.

I just posted here to "subscribe" because I need a cap and a tank and want to know the story

 

84convertablegt

New Member

Nov 6, 2004

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Columbus, OH

Jun 14, 2005

#30

• Jun 14, 2005

• #30

they are 2 different systems but im gonna say there is no difference between caps. like i said, i have a recovery tank and i didnt change caps. when it gets hot and boils over fluid runs into the tank into the bottom hole and then when it cools, fluid is sucked back into the radiator. my recovery tank also has a outlet on the top incase the recovery tanks gets too full and then it can spill out onto the ground. it just basically makes an old car perform like a new car as far as the cooling system.

 

Pakrat

Founding Member

Aug 6, 2000

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Currently: NH Originally: Rhode Island (and all po

Jun 14, 2005

#31

• Jun 14, 2005

• #31

CornerCarvin67 said:

Well this is just crazy. I can't believe this is such difficult issue. The guy at the Advance Auto Part store (older gentleman) said he's never heard of an "open" system radiator cap. And if you look on the shelf... they really all do look the same except for size. He believes... like I've also read in here... that there is just too much fluid in the system. When it gets hot and expands it creates all the pressure I'm seeing. He said the radiator cap (13lbs psi) should simply allow that pressured air to relieve itself thru the cap. Okay, fine. But at what point does the water go to my overflow tank and not thru the cap itself? Should there be some kind of pressure relief hole on the overflow tank? I didn't have any of these problems when I just had the water bottle duct taped to the hose off the radiator neck (I had to because I laid some fluid on the course during an autocross run). It was a temp fix to get me thru the day. It was by no means a tight seal at all. I'm imaging both the expanded water and the high pressure released into that bottle with no problems. Now with a sealed tank on there... it's giving me all this pressure back up. The thing that I can't really attest to is the level of fluid in the system during these different times. Maybe before I had the right amount of fluid.... and then later I managed to overfill it and create this problem. I'm so tired of this one. I'm ready to just leave the valve on the bottom of the tank open all the time and just close it during race runs to keep it from peeing on the course. I'm done with this.

Click to expand...

Well I opted not to comment yesterday and wait it out a day to see what happened but i was also not familliar with their being any cap difference between open and closed systems. My initial guess was that it was overfilled and the guy at advance would seem to agree with that. If you followed the overfill tank instructions which as you say is really no different than using a soda bottle or something to catch the over fill then it has to be an independent problem of the install so that would leave your coolant level as a suspect. has your tank captured any coolant at all or is it all back pressure? is it possible that the overfill tube running from the neck is clogged?

 

CornerCarvin67

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Dec 30, 2004

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Jun 15, 2005

#32

• Jun 15, 2005

• #32

Yep... the only difference between my water bottle and my fancy summit water overflow tank is that the tank is sealed. The water bottle could leak out the extra air pressure. I talked to a guy I work with who has extensive drag race experience and he said he's never seen an over flow tank without some kind of hole or breather to vent the pressure. So I went home last night and pull out the smallest drill bit I got and put a pin hole in the top of the overflow tank. I'll get a chance to drill it hopefully in the next day or two and follow up with an update. Thanks for everyones help...

 

302 coupe

Founding Member

Mar 2, 2000

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Macon, Ga.

Jun 15, 2005

#33

• Jun 15, 2005

• #33

Interesting. I too run a 13 lb cap and the Summit aluminum overflow bottle. I haven't noticed any excessive pressure build up though. The next time I have my car warmed up, I'll open the drain on the overflow and see if it acts like its holding pressure.

 

Edbert

Founding Member

Jul 13, 2002

3,548

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109

Austin TX

Jun 15, 2005

#34

• Jun 15, 2005

• #34

So the sealed overflow tank then is what identifies a "closed" colling system?

 

302 coupe

Founding Member

Mar 2, 2000

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Macon, Ga.

Jun 15, 2005

#35

• Jun 15, 2005

• #35

I believe it does Edbert. There is no vent to allow pressure to be released. But still, unless you were having boilover problems before the addition of the sealed overflow tank, the pressure in the system should be what it was before, less than or equal to 13 lbs (or whatever your cap is rated to).

 

CornerCarvin67

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Dec 30, 2004

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Jun 15, 2005

#36

• Jun 15, 2005

• #36

You may not have the pressure build up if you have the proper coolant level.. at least that's what I'm guessing. I'm still sketchy on the whole term "closed system". My current definition on a closed system is one that utilizes a "return resevoir"... as opposed to an overflow tank. I have an overflow tank.... simple as that. A return resevoir is constantly filling and returning coolant to the radiator during heating cycles. It's connections is usually to the bottom of the container. Where as the overflow tank has it's connection to the top of the tank. And just a hand actuated valve on the bottom to drain stuff.

At least this is the way the wind is blowing today....

302 coupe said:

Interesting. I too run a 13 lb cap and the Summit aluminum overflow bottle. I haven't noticed any excessive pressure build up though. The next time I have my car warmed up, I'll open the drain on the overflow and see if it acts like its holding pressure.

Click to expand...

 

302 coupe

Founding Member

Mar 2, 2000

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Macon, Ga.

Jun 15, 2005

#37

• Jun 15, 2005

• #37

what about running the vent hose from the radiator to the bottom of the overflow tank, with the valve open of course. Then use the top fitting on the overflow bottle as a vent. That should allow pressure to bleed out if needed, while at the same time catching excess coolant.

 

CornerCarvin67

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Dec 30, 2004

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Jun 15, 2005

#38

• Jun 15, 2005

• #38

Yep... thought about that.. might look kind of funny. Or turn the whole thing upside down. Look funny too. Good ideas though. The whole point to me getting this tank was to replace the water bottle duct taped in there. So I don't need to get fancy... as long as the car continues to run normal temperatures I'm satisfied. I'll be alright I think. Thanks for your help guys!!

302 coupe said:

what about running the vent hose from the radiator to the bottom of the overflow tank, with the valve open of course. Then use the top fitting on the overflow bottle as a vent. That should allow pressure to bleed out if needed, while at the same time catching excess coolant.

Click to expand...

 

A

a.vannoy

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Apr 13, 2005

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Jun 17, 2005

#39

• Jun 17, 2005

• #39

Check the hoses, sometimes the cheaper ones collaspe and would give you this kind of trouble. I suspect its radiator cap and thermostat related.

 

CornerCarvin67

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Dec 30, 2004

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Jun 17, 2005

#40

• Jun 17, 2005

• #40

I drilled a small hole in the top of my overflow tank. Drove the car and got her heated up good. Threw the lower valve open and it spit a little bit of fluid. No pressure built up in there like before because of the vent hole. So I closed the vent and figure now the water level has reached it's optimal level. I drove it again with some spirited pulls... parked and threw the valve open again... nothing. Everything should be okay now. Hopefully...