Yet Another Radiator Cap Pressure

**niky** · September 14th, 2014 05:11 PM

Yeah... having internet issues.

I was going to say... check your water pump... metal shavings probably mean your water pump is on its way out.

The solution to your cap dilemma should be: replace the hoses. They're the most probably failure point in your system.

**mongobread** · September 14th, 2014 09:48 PM

Originally Posted by niky

Yeah... having internet issues.

I was going to say... check your water pump... metal shavings probably mean your water pump is on its way out.

The solution to your cap dilemma should be: replace the hoses. They're the most probably failure point in your system.

Yes sir I will be replacing hoses. You've kinda answered me indirectly that I can use 1.1 cap if I've established no weak points in the cooling system.

These metal shavings are like powdery na. pag na salok mo sa tubig at tried to rub it against fingers na-didissolve. Still these are metal shavings right? Or aluminum corrosion lang? Either way, since hindi ko alam history ng water pump. I'm going to change it.

**EVO-V** · September 26th, 2014 12:46 PM

Originally Posted by mongobread

Yes sir I will be replacing hoses. You've kinda answered me indirectly that I can use 1.1 cap if I've established no weak points in the cooling system.

These metal shavings are like powdery na. pag na salok mo sa tubig at tried to rub it against fingers na-didissolve. Still these are metal shavings right? Or aluminum corrosion lang? Either way, since hindi ko alam history ng water pump. I'm going to change it.

At 1 ATM (1 bar) water's boiling point is 100C.

At 1.1 bar its at 102C, at 1.2 bar is 106C.

If your engine is overheating, that radiator cap really does little but pressurize your system making it more prone to leaks at the joints.

The reason why you want to defer boiling is because a phase change from liquid to gas makes water 40,000 time less conductive and it pressurizes the whole loop.

Then your cylinder heads glowing red hot and start warping.

If you really want to raise your boiling point without pressurizing, increase your coolant-water ratio. However, it doesn't mean just because you're not boling the water component from your coolant, that your engine isn't running hot.

Or go with a waterless coolant, 196C boiling point, and since there is no vaporization there is no pressure build up. You can practially do away with a pressure cap.

**dr. d** · September 27th, 2014 01:38 AM

Or go with a waterless coolant, 196C boiling point, and since there is no vaporization there is no pressure build up. You can practially do away with a pressure cap.[/QUOTE]

how much?
is it available to us mortals?
and is it not dangerous to the standard engine? temperatures can go beyond that of the usual water-based cooling system..?

**jick.cejoco** · September 27th, 2014 09:00 AM

you'd still need a pressure cap. it not only raises the boiling point, it also concentrates the heat to the pressurized coolant to dissipate more heat in the radiator. it also makes the water pump more efficient by reducing or eliminating pump cavitation- a result when a liquid is whipped repetitiously and rapidly creating foam.

**mongobread** · September 27th, 2014 01:51 PM

Originally Posted by mongobread

Hi to all,

I know this has been discussed before, and I've already done a lot of back reads of the threads and research in the internet.

But I want to know and want to get answers specific to the details below for more clarity:

Engine: 4g15 carb
Status of Radiator: Old/Newly overhaul/re-patched 2 times because of leak
Radiator Cap: Circuit, Silicone Type (daw) is 0.9
I bought another Cap which is federal mogul 1.1
Thermostat housing: Corroded yung kinakabitan ng hose and I see white powder sa connection nya sa engine.
Coolant: I used 2 liters of premix halvoline long life coolant, pinkish stuff before the overhaul. Now I'm running mineral water not distilled dahil yun lang avail after overhaul. I plan to use coolant 50/50 Peak brand mix w/ distilled but I'm opting to get brand new radiator at dun ko na lang gamitin.
Hoses: Looks old and I don't know the age since I got the car November 2013.
Water Pump: Looks old and I don't know the age.
Water Status: Inside the radiator I see glittery particles na parang metal shavings. It doesn't have oil in it so I know my head gasket's not blown. My mechanic confirms it.
Engine: Parang masyado mainit kahit 1/4 lang temperature. Firewall is hard to touch pag afternoon tirik araw, even the sides of the front strut mounts.
Radiator Fan: Rekta Fan
Thermostat: None
Thermoswitch: disabled or sira na ata kaya hindi na naka-connect
Temp Sending Unit: Replaced / Bnew

I have full service manual of the engine and here's the book says:

Radiator Cap
Main Valve opening pressure = 81.4-108 kPa (11.8 - 15.6 psi, 0.83-.1 kg/cm*)
Vacuum valve opening pressure = -6.86 kPa (-1.00 psi, -0.07 kg/cm*) or less

Now here's what I need clarity:
I read that increasing the pressure increases the boiling point but make sure there's no weak points in the cooling system.

I used 0.9 after the overhaul but I read na 1.1 increases boiling point.

Now based sa specs ng book I'm allowed to use 1.1, but based sa nabasa nyong status ng cooling system do you think I should stick to 0.9?

Thanks in advance.

Sirs, ang tanong ko lang po ay okay lang ba gumamit ako ng 1.1 cap kasi nakasulat naman sa manual na 0.83 - 1.1 pwede sa akin.

(See details below)

Radiator Cap
Main Valve opening pressure = 81.4-108 kPa (11.8 - 15.6 psi, 0.83-1.1 kg/cm*)
Vacuum valve opening pressure = -6.86 kPa (-1.00 psi, -0.07 kg/cm*) or less

Kumokontra kasi yung radiator shop na 0.9 lang daw dapat at mechanic ko.

Gusto ko lang ma-enlightened na kung mahina na nga ba ang hose, newley overhauled ang radiator ay wag akong mag 1.1 tulad ng sinasabi nila or it doesn't matter because I'm allowed to use 0.83 to 1.1 cap naman.

And as sir niky said:

The solution to your cap dilemma should be: replace the hoses. They're the most probably failure point in your system.

So high pressure cap may not be a good idea nga ba till I isolate weakpoints sa cooling system ko.

Again, please read the details based sa status ng cooling system ko.

**EVO-V** · September 27th, 2014 11:41 PM

Originally Posted by jick.cejoco

you'd still need a pressure cap. it not only raises the boiling point, it also concentrates the heat to the pressurized coolant to dissipate more heat in the radiator. it also makes the water pump more efficient by reducing or eliminating pump cavitation- a result when a liquid is whipped repetitiously and rapidly creating foam.

Nope you won't. If by the time you even reach the boiling point using a waterless coolant, your engine would have long shut itself off.

And since you really don't have air, assuming your cooling system is properly primed, there would be no cavitation issues for the pump to deal with.

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**EVO-V** · September 27th, 2014 11:55 PM

Originally Posted by mongobread

Sirs, ang tanong ko lang po ay okay lang ba gumamit ako ng 1.1 cap kasi nakasulat naman sa manual na 0.83 - 1.1 pwede sa akin.

(See details below)

Kumokontra kasi yung radiator shop na 0.9 lang daw dapat at mechanic ko.

Gusto ko lang ma-enlightened na kung mahina na nga ba ang hose, newley overhauled ang radiator ay wag akong mag 1.1 tulad ng sinasabi nila or it doesn't matter because I'm allowed to use 0.83 to 1.1 cap naman.

And as sir niky said:

So high pressure cap may not be a good idea nga ba till I isolate weakpoints sa cooling system ko.

Again, please read the details based sa status ng cooling system ko.

At 1.1 bars the boiling point of water is 102C. If by any chance your radiator finds itself having a hard time keeping you below 96C, the high pressure cap is the least of your concerns. Don't strain your system any further.

And seriously, radiator "overhauling" is really a bandaid for light vehicles. There are a host of cheap radiators you can get nowadays. Get a new one. Don't skimp. An engine overhaul is just one overheating incident away from ruining your month.

**mongobread** · September 28th, 2014 12:06 AM

Originally Posted by EVO-V

At 1.1 bars the boiling point of water is 102C. If by any chance your radiator finds itself having a hard time keeping you below 96C, the high pressure cap is the least of your concerns. Don't strain your system any further.

And seriously, radiator "overhauling" is really a bandaid for light vehicles. There are a host of cheap radiators you can get nowadays. Get a new one. Don't skimp. An engine overhaul is just one overheating incident away from ruining your month.

Yes sir, I do plan to get a new radiator. For the meantime lang ito till I'm done w/ the tirik scenario of the engine (Ignition Coil overheat issue) but that's another topic.

My cooling system is fairly fine naman kahit bago ako mag pa-patch/overhaul. Hindi naman nataas sa middle ang temperature ko.

I just want to know lang naman if putting 1.1 cap on my radiator is really bad because everyone seems to be telling me to go back to 0.9 cap kahit na ang allowable spec sa akin ay 0.83 to 1.1 cap.

Ang debate ko kasi sa kanila ay mas matagal umangat naman ang temp needle ko kaya I thought increasing the boiling point helps.

I just want justification and clarity for knowledge sake if I use 1.1 cap is really bad for me na.

**mongobread** · September 28th, 2014 12:08 AM

And to add, they scold me not to put thermostat which I debate with that why not and why I should? Hindi naman makasagot sa ano pa silbi ng radiator if the water/coolant is being circulated all the time.

Kaya nga daw nakarekta na yun radiator fan ko, eh kako bugbog naman and I don't think kaya nyang palamigin talaga ang radiator lalo't stop and go sa bumper to bumper scenario.

For the record I do plan to restore everything, from thermostat to thermoswitch and new radiator.