rad cap

[tazman]

does anyone know if there is a differance on radior caps on a closed syestem and a recovery seyestem

[gr8scott51]

Don't know it for a fact, but if you run less than a 16 pound cap, you better have a recovery system. Even with a 4 row and 16 pound cap, I need a recovery system. I used to leave a small puddle when I parked.

[Mechanic]

Stant makes both types of caps in multiple pressures. In other words they make an open system 16psi cap, and a closed system 16psi cap. BTW, Greatscott is right on making a recovery system too. I use Caterpillar long life AF and I hated seeing it go all over the ground. Good Luck.

[tazman]

thanks guys not leaving any puddles --rad just mounted in a spot that I can not easily get to

[Longhorn Man]

gr8scott51, if you would have only filled it to about an inch or so from the cap, you wouldn't have lost any onless you were over heating.
The caps for systems with a puke tank have the ability to suck the coolant back into the rad.
Closed system caps will spit it out, but not suck it back in.

[Mechanic]

My '71 Cheyenne big block tended to lose antifreeze out the overflow tube, so I changed caps, added a surge tank, and walaa! No more lost coolant.

It's not a matter of overheating, but rather, the physics of expansion. Or, let me put it another way...if you exchange your Silverado's "puke tank" with a hose pointing to the ground, you'll end up with a puddle on the ground. Then you will get low on water. Then you'll overheat.

What Stant did is design a cap that allows flow both ways by allowing pressure to force expanding hot coolant into the surge tank at a certain psi, and vacuum to bring it back when the radiator cools. As long as the seal on the cap is sound, you're ok. Assuming a good radiator and a surge tank with no holes, and a decent hose connecting the two.

Hope this helps.

[smokekiki]

Like longhornmail said,with a closed system,Don't fill it to the very top.

[Longhorn Man]

Exactly. You aren't supposed to fill them all the way up. If you are running at normal operating temps, you will only an inch or two down and if you over heat like that, then you need to address your cooling system.

[Mechanic]

Yep...that's what I thought. I suppose my 102 3208T and 3126T Caterpillar powered buses all need their cooling systems "addressed?" And I suppose my Allison transmissions shouldn't be serviced either! LMAO

So, how's a radiator supposed to know if it's a "closed system" or a "puke tank system?" Is it a generational thing? LOL How's a big block to know which system it can match up with? Old timers like mine must only use systems that drain out the overflow tube, while newer, lucky big blocks get the luxury of having systems that capture all that "unaddressed" coolant? HA

The problem with boards like this is that if a guy's going to pull his horse trailer to Montana from Washington each year, and go elk hunting with his big ole 1967 camper, he may learn a thing or two about trucks, towing, and temperature. Then some moron comes along with crap like this. Or crap like changing your trans fluid is a bad idea. (another post) So after about 2 days I'm thinkin I stumbled into something that just going to aggravate me to no end.

So I guess I'll go back to just driving my 1 owner, 1971 Cheyenne, into the ground. That's right, 402, Turbo400 w/American Overdrive, 410, 4Row, non-overheatin' surge-tank equiped, olive green, customer ordered, custom sport truck. So like Longpornmale said...Exactly.

[smokekiki]

He asked if there was a diff in rad caps.Tell us how full should his rad should be if he has a system without a recovery tank.This is what the General says in the owners manual from my suburban...Coolant level should be three inches below the level of the filler neck when the engine is cold.Further back in the manual it says a 195 thermostat is stock and a 15psi cap,ac type RC15. It is the original manual.

[smokekiki]

Mechanic,you may be right.You did get on the wrong board if you want to call others morons.This is the only board I have ever been on where there is no name calling and everyone gets to post there opinion,and you do not have to be in the clique to get an answer.

[krue]

I have to agree with smokekiki, if you want to call names, move on, cuz we don't need you. If you want to talk about trucks, stick around, you might even learn somthing.

[Mechanic]

Ya, you're both right. My apologies.

[Baradium]

Open system: You never leave them full. You find out what level it likes where it won't puke any out and that's where you keep it. Radiator is designed to take this into account. You do not need to change cap pressure based on this. I use a 7lb cap on mine and wouldn't reccomend higher than 13 (factory pressure) without a brand new system. I'd prefer less than 10 for a system as old as ours. Only reason you need higher pressure is if you have problems with overheating (the higher pressure lets you get to a higher temp before you get boiling). There are some types of coolant (very $$$) that do not require any pressure to work correctly.

There is no difference in caps and do not worry if your radiator isn't always filled all the way to the top. You just want it full when it's at it's maximum operating temperature. A recovery tank doesn't hurt, but is not neccessary for systems designed not to need one.

[krue]

BTW welcome to the board!

[tazman]

I guess i should clairfiy something-- I do not have a problem whats is going on is I have a custom job and when the rad was put in -its in a spot that i can not get to the cap with out takeing the rad loose. what I am trying to do is put a puke tank syestem so i can put water in whithout messing with the rad. oh by the way I live in the desert. What I have is a 71 Vega custom pick-up[no its not from the factory] with a 327 stroker