radiator caps, cooling system pressure

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It would just change it to the pressure for AC cars. For it's first 52 years of use it was without AC. I added AC to it.
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wrote:

If that is factory spec, it should be OK. OTOH, since it is over 50 years old, I'd not want to increase pressure if I did not have to.
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Actually, the spec is14psi on the 60, but I often put a lower pressure cap on an older car to protect the rad. If the rad is solid, and the heater core is solid, and the hoses are good, you should be ok with the 14 lb cap. But that's a big if.
If the temperature is well under 210F with the air on, you don't need the heavy cap - and that's not nearly as big an if, generally speaking.
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Ed Pawlowski wrote:

Hi, As well today's cars are monitored and controlled by computers. Better not fool around.
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imoto-high-pressure-radiator-cap-13-bar....

The only way to increase the system pressure would be to change the thermostat to a higher temperature one so increasing temperature as well as pressure. You would then have to change the radiator cap too. But changing the radiator cap alone wouldn't change the pressure but in the event of engine overheat/pressure would negate the protection it gives.
Very unwise, you may get hoses bursting and engine overheating . If your engine is overheating there is a problem with the radiator (blocked) or the thermostat not fully opening. Possibly slack belt (drives the water pump). Electric fan (or it's thermostat) if it has one faulty. Waterways in cylinder block/head blocked/corroded.
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,

shimoto-high-pressure-radiator-cap-13-bar....

Dumb as ever. The current cap releases pressure at 7 PSI when the car overheats. He's proposing changing it to 13 PSI so that when it is overheating, it will not release until that higher pressure is reached. That results in a higher pressure when overheating exactly as he claimed and doesn't require changing the thermostat.

Dumb as ever. When the engine overheats, which is what he's specifically concerned about, having that higher pressure cap will result in higher pressure.

That part is correct. Even a stopped clock is occasionally correct.
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On Sun, 21 Apr 2013 23:31:02 -0700 (PDT), harry

Harry, you are incorrect on this. The cap alone WILL cause most suystems to run at a higher pressure as long as the vehicle runs at a minimum of 160F. The thermostat only controls the MINIMUM operating temperature of an engine, so even an engine with a 160 thermostat can run at 195F, or higher. The cap allows the pressure to build to a MAXIMUM of the rated pressure - at which point it releases into the overflow to regulate the pressure.

Or bad timing, or bad mixture, or simply overloading the engine. But yes, you got ONE thing right - installing a cap with a pressure higher than the system is designed for CAN cause problems with hoses, radiators, heater cores, etc..
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On 04/22/2013 02:31 AM, harry wrote:

What? you haven't any clue how a cooling system works do you? Please just shut up if you don't have any knowledge of what the fuck you're talking about.
nate
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Lots of comments--my two cents: First of all, the water pump is a centrifugal pump and as such the pressure rise across the pump is a function of it's speed. The flow output of the pump is a function of the system characteristics-- Pressure drop vs Flow So changing pressure caps and thermostats will not change the operating behavior of the pump. The purpose of the pressure cap is to raise the boiling point of the fluid. This allows you to run the coolant at higher temperatures (greater than 212F) without causing it to boil. Just because you have a 180 deg thermostat doesn't mean that the coolant at running at 180 deg-----because of the cap, typically, the coolant boiling point is closer to 234 deg F (or higher). That's why they say never to remove the cap until the coolant cools down--if you remove the cap too soon, the system pressure becomes 15 psia (atmospheric). the boiling point becomes 212F and you get a great big flash of steam as the coolant immediately changes from a liquid to a vapor. As the coolant temperature increases, it's density (Specific Gravity) decreases and because it's weight remains constant, the only other variable is it's volume which increases. Because the cooling system volume is fixed the coolant pressure will increase (no room to expand) from atmospheric to whatever the cap is set for and then it is vented to the over-flow bottle. The downside of increasing the pressure cap setting over what's specified is two fold---At the higher cap setting, all the system components will be subjected to pressures beyond design intent--not a good idea. The same applies to the operating temperature. In summer like days the coolant temperature will go beyond normal design intent. In both cases, you're moving in a direction to accelerate component failures. MLD
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Thoughts?????
One other possibility is you may have a blown head gasket.
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The other very real possibility is that harry is the village idiot, as has been proven time and time again.
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wrote:

Exhaust gases from a slight head gasket leak will boil the water and over pressure the system. You don't really know much do you?
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On Mon, 22 Apr 2013 22:53:32 -0700 (PDT), harry

Actually the gasses from the leak pressurize the system, blowing the water out - which causes overheating. Harry doesn't know much either.
Been proven many times.
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On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry

Which WILL cause the pressure to increase rapidly if it is causing an overheating problem - and even a 30psi cap would vent under these conditions
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On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry

I didn't want to make the original post into a novel but it appears a lot is being read into what wasn't included. That car is not having any problems at all right now. I'm just looking at increasing the factor of safety against overheating because I just added AC to it. Non-ac cars use a 7 pound cap and AC uses 13. But it's a 52 year old car (well maintained) and the downside would be if adding 6 pounds more pressure is likely to create any leaks, like in the 52 year old heater core. Nothing leaks now. I'm just torn between being proactive and getting a higher pressure cap "just in case", or just sitting tight and seeing how the temperatures run as the weather heats up.
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On 04/22/2013 02:50 PM, Ashton Crusher wrote:

Like I said in a previous post, a coolant recovery bottle would be my first step... I never did like seeing that air gap at the top of the radiator, and it's not good for anything to have it there.
nate
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wrote:

Prior owner put one on it and it seems to be working correctly.
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wrote:

Making a big mistake. I've already shopped it to a publicsher, and he's discussed it with a NY producer. Since you hadn't even though of it, I'll take 17 percent. Contact me at Telex;723345.

Your conflating over-pressure with over-heating. Containing the pressure won't make it cooler.

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adding a transmission oil cooler is probaly a good idea:) with a transmission oil filter in series it might save a expensive transmission rebuid someday:)
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On Sunday, April 21, 2013 3:21:32 PM UTC-7, Ashton Crusher wrote:

I live in Arizona, and nobody in my family here has ever had an overheating problem that wasn't caused by a burst hose or bad radiator cap, and I know the latter happened in fall or winter. The hose that broke was a flex hose -- never use those if you don't have to. The bad radiator caps were brand new replacements -- 2 in a row gushed out coolant on day one, while the ~5-year-old factory original cap and a replacement from a car dealer worked fine. Also I once bought 3 bad thermostats in a row -- when I tested them in a pot of hot water with a thermostat, one wouldn't open more than 1/4", the other two opened wide at about 150F (rated 195F). So for radiator caps and thermostats, I use only OEM.
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