Technical Cooling system pressure

Is it just newer engines that require it,my 37 Chevy has a non pressure system and a 57 235 and it can sit and idle all day long with a four blade fan and not go over 180. I done some changes to my 55 Ford that has a 351 W that had a 7 pound cap and a factory 5 blade a/c fan that the temp would occasionally creep at idle sitting in traffic bur the changes I done required going back to a four blade fan due to lack of room and it instantly started gettng hotter at idle so I put a 13 pound cap on and I think I solved that problem. I had numerous 60s and older vehicles that the pressure in the cooling system did not seemed to matter and never got hotter idling.

 

Higher pressure cap raises the boiling point of the coolant so the motor can run hotter without boiling and blowing the coolant out. Higher pressure/boiling point will help stop steam pockets from forming at hot spots in the motor, usually by the exhaust valves, which could help the motor run a little cooler on the gauge.

 

A pressure cap doesn't change the temperature. It changes the temperature at which the coolant boils.

Also, if you are determining temperature by the gauge in a 55 Ford, they aren't very accurate. I always determined if an engine was getting too hot by looking to see if it was venting any coolant. My 57 T-Bird will get pretty high up on the gauge in slow traffic and hot weather. However, it never loses any coolant, so I quit worrying about it.

 

If it's an original radiator, and came with a 7 lb cap, you're asking for trouble with a 13 lb cap. The radiator tanks are not designed to withstand that much pressure, and could get bulged and leak.

Some aftermarket radiators have different tank design, and can take the pressure.

 

It has a new aluminum radiator and a 13 pound cap is what it was supposed to have in 55.

 

Might be time for a fan shroud too since the fan sits lower then it did originally.

 

Rockauto lists six different ones, all are 7psi.

 

Local parts store said 13 unless he thought I said 1965,going to try it and see how it does but the gauge quit creeping up for now with more pressure.

 

Local parts store also told me my little '90s car used gear oil in the transmission, when it actually takes ATF.

 

It has a 80s engine that most likely had a higher pressure so I do not think it will hurt it,when it goes back to a Y block I will put the 7# cap back on.

 

You'r problem is air movement , you need good fan blade and a shroud.

 

I really do not like the fan I got but not much else will fit without relocating the alternator but do not want to go through that since a Y block will be going in soon and that will fix the fan problems.

 

A pressurized system also prevents some fluid loss vs a unpressurized system.
A unpressurized system can lose fluid at high speed Rpms.