# How does a cooling system work?



## noquacks (Jun 5, 2010)

What I mean is, say you have a slow leak in the radiator, and you loose X amount of rad fluid every month. Now, say you release pressure in the rad cap to the 1st "notch/position" on the cap so to lessen the psi. Wouldnt that allow for less fluid loss? This is to put off this project until about late August at which time I should be able to install a new rad. 

What hapens when you dont close the rad cap all the way? Could get easier boiling of rad fluid?


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## booths auto (Jul 3, 2012)

Loosening the will reduce pressure in the cooling system , which will reduce the loss of coolant . It will obviously be a temporary fix and the coolant should be checked regularly.


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## polarzak (Dec 1, 2008)

Loosening the rad cap will reduce the pressure, which in turn lowers the boiling point of the coolant. The water in the coolant will boil quicker resulting in vaporization and loss. Frankly I wouldn't do it to my engine, I would get it fixed. Or try some of that rad stop leak. It might work. Depending where you live, we have an awful lot of real hot days in the forecast.


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## Bondo (Dec 8, 2007)

polarzak said:


> Loosening the rad cap will reduce the pressure, which in turn lowers the boiling point of the coolant. The water in the coolant will boil quicker resulting in vaporization and loss. Frankly I wouldn't do it to my engine, I would get it fixed. Or try some of that rad stop leak. It might work. Depending where you live, we have an awful lot of real hot days in the forecast.


Ayuh,... Exactly,.... Puttin' off fixin' the coolin' system, til *After* the hottest time of year, is kinda counter common sense...

Matter of fact,... it's Lookin' for trouble, 'n aggravation...


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## cjm94 (Sep 25, 2011)

Stop leak may buy you some time, but could plug your heater core and cost you more later. Driving with a loose cap you will blow out your coolant when it gets hot.


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## noquacks (Jun 5, 2010)

cjm94 said:


> Stop leak may buy you some time, but could plug your heater core and cost you more later. Driving with a loose cap you will blow out your coolant when it gets hot.


Right. No stop leak for me ever. Not in my rad, not in my ac. But, people, I cant get to this repair in the next 5-6 weeks. Yes, I may lose water as vapor, but thats why I will hAVE TO monitor it weekly. 

I did pressure test the system and at 15 psi there was no VISIBLE leakage at the rad. I even placed a cardboard below the entire front end of the car in case I would not see a drop or 2 - no spotting on the cardboard. 

The mechanic said it leaked. So trust is a big factor here. head gasket is starting to fail , thats for sure. I said STARTING. I am on borrowed time, I know.

Thnaks, people.


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## cjm94 (Sep 25, 2011)

Some leaks can be hard to find. You may have to psi test it stone cold and then start it and monitor it as it warms. With all the plastic and aluminum parts they sometimes only leak at certain temps. If it is that slow you should makes it that long keeping an eye on it. Just keep some coolant with you.


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## Bondo (Dec 8, 2007)

noquacks said:


> Right. No stop leak for me ever. Not in my rad, not in my ac. But, people, I cant get to this repair in the next 5-6 weeks. Yes, I may lose water as vapor, but thats why I will hAVE TO monitor it weekly.
> 
> *I did pressure test the system and at 15 psi there was no VISIBLE leakage* at the rad. I even placed a cardboard below the entire front end of the car in case I would not see a drop or 2 - no spotting on the cardboard.
> 
> ...


Ayuh,... But did the pressure drop,..??


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## Duckweather (Mar 26, 2012)

That leak sounds internal. You say the head gasket is bad? if the exhaust gets in through that head gasket it will add heat to the coolant. When, or if you change the head gasket, you should check for cracks in the block. They can close up when engine is cold and open as the engine gets hot and parts expand causing fluid loss.


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## bwilliams (Jul 4, 2012)

First of all, I don't see any information about the vehicle in the way of make, model, year and engine size. Vehicles have certain traits that are inherent in the vehicle. How long has the coolant been in the system before it started to lose it? If it is over five years (EG type), than perhaps it is turning acidic and eating away at the head gaskets. Not so likely if it is longlife coolant but still possible. If you tested it and found no leaks, there is a good possibility that it is an internal leak and loosening off the cap is not going to be doing you nay favors. This type of leak needs to be fixed promptly or risk severe engine damage. You need to pressure test hot and cold and do a block test for exhaust presence in the cooling system. When you pressure test, not only look for leaks, but watch the pressure. Sometimes, pressure will drop with no leaks = loose hose clamps. Hope this helps. One last thing, any type of sealer for any type of system is a bandaid and usually does more harm than good in the long run. Good luck


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## DoyleSumrall (Oct 4, 2012)

Loosening the will reduce pressure in your car's cooling system , which will reduce the loss of radiator coolant . It will obviously be a temporary fix and the coolant should be checked regularly.


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## D-rock (May 23, 2011)

You need to keep the cap tight and the coolant full. If not then fluid can just shot out the loose radiator cap and will make things worse. Check it every other day or so to make sure its full. DO NOT OPEN CAP WHEN ENGINE IS HOT it can and will burn you, blow in your face and make you have a bad day. Just keep it full and it will survive until you can have it repaired. Suggest not using any stop leak, if its a blown head gasket then it would not likely do anything anyways. Stop leak has been known to clog up stuff and make a mess.


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## imautoparts (Oct 10, 2012)

I've used stop leak many, many times, and never once regretted it. Try to get the kind that looks like aluminum powder.

It will either work or it will not. If it does not, get your antifreeze changed completely with whatever repair is needed.

My 2c


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## Jess_718 (Oct 15, 2012)

*Cooling system*

My friend replaced his coolant in his car. It was a big job. HE is a car technician.


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## AZBaobab (Oct 31, 2012)

I'll throw in my two cents, as I had a simlar issue.
Note that as posted, different cars have different characteristics, and my experience was on a '95 Land Cruiser.

The radiator had a hair-line crack up at the very top. So, steam and a tiny bit of fluid would leak out. However, as the fluid level stayed relatively high, I kept an eye on it, and didn't think much of it. Until the squeaking started...

Evidently (at least, this is what I was told by a VERY reputable Land Cruise specialist) if the system has a leak, it won't pressurize properly: regardless of fluid levels. 
And if it doesn't pressurize properly, undue stress is being put on the water pump... which in turn burns out the bearing very quickly.
So, what would have originally been just a radiator job, turned into a radiator AND a water-pump job.

So, while that may not be the case with your car, DON'T put off getting it fixed, because it may have serious implications for other components of the system = expensive failures.


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