Radiator Capacity vs Pressure

[MaximaGuy]

I bought a new radiator for my Maxima and installed it and finally (there is another thread out there) flushed it with Nissan Long Life Coolant.

Couple of things that is confusing me, the new radiator is 150% the depth of the OEM radiator. Now the capacity of the new radiator is said to be 181cc but then when I drained the new radiator, I got out more than 4 quarts.

The new radiator works like a gem but then its capacity is more than the stock radiator (I don't even know the capacity of the OEM one but the new one is deeper than the stock radiator).

1 gallon = 4 quarts (231 cubic inches)= 3.785 liters

Now, the coolant is not boiling and there is very less pressure on the radiator cap (OEM) and no coolant loss.

Should I be concerned that there is not much pressure in the closed loop system, am I missing something here, do I need a higher pressure radiator cap.

 

[George7941]

The fact that the pressure developed is low makes me suspect that there is a lot of air left in the system. Does the coolant level in the overflow bottle rise and fall as the engine heats up and cools down? Of course we are assuming that your rad cap is still good.

 

[MaximaGuy]

Positive, no air in the system.

Burped the sucker many times, 2 times vias the air-relief valve and 3 times in a closed loop system and with radiator cap off. There is no overflow into the tank and minimal draw from the tank.

 

[toocrazy2yoo]

May be that the higher capacity radiator isn't going to ALLOW the pressure to go as high because it's exchanging 50% more heat. How do you know the pressure, are you using a gauge on the cap? Also, are you able to gauge the temperature one way or the other? There are only a couple of things keeping the pressure from building, and for that matter, ar you certain you don't have a leak to the intake, or through the head gasket, or to the outside you aren't noticing?

 

[MaximaGuy]

Quote:

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How do you know the pressure, are you using a gauge on the cap? There are only a couple of things keeping the pressure from building, and for that matter, ar you certain you don't have a leak to the intake, or through the head gasket, or to the outside you aren't noticing?

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Well, the radiator cap is new. Now when I had the old radiator (or in any other vehicle) when the system is presurized, one cannot turn the radiator cap and only when the pressure releases the cap can be turned. In my case after a long drive, I can turn my cap, though I wouldn't be (

) to open it all the way and have coolant spewed all over the place.

The upper and lower hoses are tight meaning there is pressure building up, nicely..

 

[unDummy]

Don't worry about it. Thats the positive side effect of better cooling. There aren't too many stock replacement radiators that cool better then OEM.

With a bigger rad, your fans should cycle less often. And, since the rad holds more water, the fans might run a tad longer when they turn on. The cycling frequency is less and cycling run time is longer.

As long as there is pressure, quit worrying. All it takes is some traffic to peak the pressure for the cap to work.

Don't use a higher PSI cap.

Make sure overflow hose does't have any leaks. You might need to trim it at the bottle and at the cap.

 

[toocrazy2yoo]

Either way, the thermostat is going to allow the engine to reach temp, you'll be fine.

I have no idea where the extra room under the hood came from, but good on ya!

 

[alreadygone]

Only on BITOG would folks worry about good things ! More capacity is a good thing, lower pressure is a good thing. Why on earth would you want a higher prssure cap, when it's not building enough pressure to make the present one overflow?

Bob

 

[toocrazy2yoo]

 

[The_Jeff]

The friction you feel turning the old cap to its almost-open stop is probably just a function of time, age, and corrosion either on the cap or filler neck or both. Truly the two are jammed together by the few PSI when it's warm but the amount of friction seems like a red herring in this case.

It's possible that 181 cc capacity for the rad is for the cooling fin/tube portion and excludes the end tanks. I think it's an odd spec but might be related to heat exchange-ability compared to stock or something.

 

[porcupine73]

If it is lower pressure that's a good thing. Maybe you got a radiator for a turbo engine or something; anyway extra cooling capacity will come in handy in case you decide to tour death valley.