Coolant help

[1985VK]

OK so if there is increased pressure the boiling point is higher so would it run cooler? I don't know why some systems run 13psi others at 15psi and others at 21psi What are the contributing factors for an overheat?

 

[losh1971]

I have a leak in my heater core. To remove the dash is just plain ****. However the there is a sneaky way that only takes an hour or so. It does mean cutting the pipes on the cabin side of the firewall though and using heater hose over the join.

 

[losh1971]

Just while we are on the subject. Is it not the glycol that inhibits the corrosion? Or is ir some other additive? I need antfreeze as we get regular minus 10s. But if i could find something that has anti corrosion properties and still lowers the freezing point that would be really good. I suspect i have too much coolant ratio which is affecting the cooling effectiveness of my system.

 

[Immortality]

OK so if there is increased pressure the boiling point is higher so would it run cooler? I don't know why some systems run 13psi others at 15psi and others at 21psi What are the contributing factors for an overheat?

I'm no expert but materials and age of the design no doubt plays a part as does the intended power output, more power = more heat. Old engines didn't make a lot of power so less wasted heat to get rid off as well as lesser quality materials to stand up to the pressure in the system.

Overheating occurs when your system can't remove the heat fast enough and that can be caused by any number of scenarios, failing water pump, blocked hoses, blocked radiator (core and/or airflow) etc. My understanding is that when the coolant starts to boil it looses it's ability to transfer heat, also localised boiling spots inside the engine create air pockets, air acts like an insulator so no more heat transfer which means more heat in that spot and once that starts unless you get rid off the heat (or the source of the heat) it's a self perpetuating cycle ultimately leading to engine failure...

 

[Wozza]

Heat transfer is done by the water in the cooling system, H20 is the best (cheapest) for transferring heat from metal parts...all the other stuff if added to the cooling system is just to help protect dissimilar metals and give you a bit more of an overhead in extreme conditions...no coolant in race cars but that said no race car is going to do 1/2 million kays on a single motor meh......your just wasting good money on expensive coolant as bloody commodores spit the stuff out at alarming rates...yeah I know your cooling system is tight never leaks ....never say never...as we speak the car is plotting its next major spew ......

 

[mechanic]

Radiator coolant has many jobs (some obvious, some not so):

To raise the boiling point
To lower the freezing point
To absorb energy quickly from the hot engine
To carry energy from the engine to the radiator
To be easily mobile and non-adhesive (flow quickly from one place to another without a layer sticking to a surface)
To be able to dump that energy quickly while in the radiator
To protect the metal surfaces from oxidisation (rust/corrosion)
To inhibit galvanic corrosion (pitting) from dissimilar metals in close proximity
To lubricate and condition the rubber seals and hoses
To carry/suspend debris so that it doesn't sediment in places
To minimise cavitation effects of the fast moving water pump blades
To neutralise any acid/alkaline conditions caused within the fluid over time
To minimise chemical reactions with other coolant types (to a degree)
To remain electrically conductive throughout its life
And others not related to engine operation such as bittering agents, colouring etc

There are probably more, but this is all I could think of in 3 minutes.

Someone already mentioned that plain water is one of the best coolants known, and that is pretty true. Trouble is that water doesn't provide any of the other advantages listed above.
Coolant actually absorbs heat best when the outer surface of the cylinder liner develops short-term micro-bubbles (like your kettle does just before it boils proper). It needs the water component mixed in for this to happen.

 

[Immortality]

Correct, that is why you can buy corrosive inhibitors that provide some of the other benefits.

I use this https://www.penriteoil.com.au/products/10-tenths-race-coolant-inhibitor#/

 

[VPRob]

Im actually considering a different type of coolant mainly because my engine gets too hot on steep hills with air going at the same time. I want one that can have a higher ratio of water. straight water in a properly functioning v6 system should boil higher than 100c because the water is under pressure

My VP (VR motor) runs hot on steep climbs also , or at least that's what the gauge says. I'm interested to learn that the Penrite 50/50 mix I have been using isn't necessarily the most efficient at getting rid of heat. I had been considering a new, heavy duty water pump which MAY circulate the coolant faster. My water pump is about 7 or 8 years old. Temp gauge hardly gets off cold in winter but climbs to scarey levels on a hot summer day, esp if a long climb is involved. What do you think?

 

[Lex]

If w/pump is 7 - 8 years old, maybe its due for replacement.
Do you have working a/c? If so, hows the engine temp when switched on? Does the temp rise? If so, maybe the the pump is cactus?

 

[losh1971]

Rob mine gets up to temp in the winter but like yours get close to red on a hot day, climbing with aircon on. EYY suggested replacing the temperature sensor for the gauge as it could be reading wrong as they can do after some time. My pump is less than a month old so im ruling out that. I don't know that a hi-flow pump is the go as it may not help as what you need is more heat exchange. A new bigger capacity rad would help i suspect.