Monday, March 25th, 2013

A View from the Pumps: Automotive Cooling Systems Part 2

old style radiatorsteaming

Automotive Colling Systems

After last weeks over simplification of the cooling system, this week’s goal is to explain how many systems actually rely on the cooling system to work properly. Almost every system in the power train, that uses any kind of fluid or gas to operate is totally reliant on the engines ability to generate, maintain and control the heat generated by the internal combustion in the bowels of the engine. You might be asking just how many systems are involved.

Let’s count:

1. Obviously there is the heater system, not that we use it very often down here.
2. The air conditioning system which we use all the time down here.
3. The transmission, failure here can cost you thousands of dollars.
4. The oil lubrication system, which can also cost you thousands of dollars.
5. The power steering system.

Oil Based Systems

I think that in the essence of simplicity we’ll address the oil based systems ie. the engine oil, transmission fluid and the power steering fluid first. It’s not a commonly known fact that the temperature of the engine oil, transmission fluid and power steering fluid all have to be within 10% of each other at all times. At start up that is as little as 8 degrees, and only as high as 22 degrees when everything is up and running at its optimum. MATH TIME!!!!! What is the optimum temperature of today’s’ engine? Answer: 227 degrees. What is the difference between 211 and 212 degrees, the physics of fluid and steam, how do we reach and maintain 227 degrees as the norm? Pressure and additives.

Bad radiator cap images

Oils Have a Double Job

Oils have a double job in most instances it’s used as a lubricant and a cooling agent to help the exchange of heat. Oils do not like two things, excessive heat or excessive cold. This is why all of you folks from Canada, Upper Michigan and Wisconsin, plug in block heaters at night. You might have thought it was so that the coolant wouldn’t freeze and blow out those expansion plugs (most commonly known as freeze out plugs). But in all reality it is to keep that delicate balance between all of these fluids in check. When oils get cold they tend to gel or wax, ask any old-time trucker how many times he has had to change a fuel filter because of paraffin. But when these same oils get overheated they start to oxidize. Oxidation makes oils lose their lubricity. That is: that they become less slippery. Oxidized oils make seals turn hard, so hard in fact that they can shave the inside of the bores inside of steering racks and master cylinder bores, causing internal pressure losses which is the primary source of failure in those two components.

Engine oil on the other hand, not only loses its lubricity, but much worse, it turns to sludge. Sludge in an engine is death! There is no two ways about it; a sludge up engine will cause massive amounts of wear and damage internally, so that the only way to revive those vehicles is by engine replacement or overhaul. Those are some pretty stiff prices to pay when all you had to do was to monitor your vehicle’s cooling system’s operation and performance. Almost every radiator in today’s vehicles has engine oil and a transmission fluid cooler built right into the radiator. Most power steering systems have an external cooler mounted either in front of the condenser or behind the radiator to cool that fluid radiantly (more physics).

checking for combustion gasses or PH images
The next two operations that deal with the cooling system even on a more one on one basis is heating and air conditioning, otherwise known as HVAC, unless you are fortunate enough to own an upper end vehicle where upon its known as “COMFORT CONTROLS”.

Having Enough Cooling System Fluid

It’s very obvious that if you don’t have enough fluid in your cooling system you will never have heat. Remember those cold mornings when you had to race the engine to 2500 rpms to get even a little heat to clear your windshield? BUT: we live in sunny South West Florida, we don’t need no heat! Oh but we do. Because today’s’ systems use blend doors to control the hot to cold relationship unlike the heater control valve from the old times. Back then you were either sweating or freezing using the window to either cool down or warm up as we motored about. In some locales using the windows to control the heating or cooling of the passenger compartment was referred to as 260 air.

Climate Control

That is two windows open at 60 miles per hour. Now we have climate control, so we can fill our cabin areas with the right amount of heat and cold to have the passenger compartment stay at a wonderful 74 degrees. In front of the radiator lays the air conditioning condenser. The condenser is really a radiator that is built to maintain pressures as high as 500psi, as opposed to the 21psi that radiators hold. The condenser does one thing, it condenses a high pressure super-heated gas (Freon) into a high pressure super-heated liquid (there’s that damn physics again) by cooling it down. And how do you suppose that is accomplished? Why of course it’s the radiator which is the major player of the cooling system.

Next Week

Next week we’ll talk about how the cooling system is controlled and how so much of it can be accomplished by maintaining the cooling system and its various components.



Gregg’s Automotive Maintenance & Repair Center

236 S. Tamiami Tr.
Punta Gorda, Fl. 33950