- Mon, Apr 2, 2007
Early Spring Greetings from Thawing Nappanee….
The birds are chirping, the temperatures are moderating, and spring is apparently making its bid to return to the Midwest. I can't wait. I find as my age has advanced, so my body's tolerance for really cold weather has not.
Speaking of tolerances for cold weather, let's get back to last month's conversation on cooling systems and their tolerance (or occasional lack thereof) for any kind of weather….
Last time we discussed the basics of a vehicles cooling system, and how they work together to dissipate the enormous heat that is built up during the process of running an internal combustion engine. We talked about how the cooling system uses a water pump on the engine to circulate an ethyl glycol and water solution through pockets and "jackets" in the engine to absorb the heat being generated, then how that solution is passed through a radiator to remove the heat before being sent back to the engine. We also talked about how the radiator cap maintains a certain level of pressure in the system to improve the heat absorbing capability of the coolant solution. When all the components in the cooling system are functioning correctly, the engine operates at peak efficiency, and all is well.
Of course, if it isn't working well, it can be no fun at all. The key to keeping your cooling system … well, cool… is like everything else; it's all about maintenance. So you've got this slimy green (or now sometimes orange or red) fluid, and a bunch of hoses, and a radiator and such… what is there to maintain on a cooling system? Actually, there's quite a bit.
First is the fluid itself. The fluid should always be clean; bright in color without rust, corrosion, or sediment floating around in it. It should not be cloudy, or "milky" (usually a BAD sign), and it should also not be too strong. As we discussed last month, a 50/50 mix of water and ethyl glycol antifreeze offers excellent protection against freezing, while also providing the correct levels of heat protection as well. Keep the coolant changed; just like oil, coolant eventually wears out, too, so follow your vehicle manufacturers recommended replacement intervals.
Perhaps the most overlooked area of cooling system maintenance is the radiator. Keeping it topped off is just the tip of the maintenance iceberg. You need to keep the fins clean… very clean. Road debris, especially bugs, and impacts from larger things (birds, sticks, etc.) can greatly decrease the radiators ability to dissipate the heat the coolant brings to it. Spray the radiator fins with water or air, or gently brush them with a very soft bristle brush. The fins on a radiator are very delicate, and are easily damaged or bent. When spraying them off, try to use indirect force, and avoid high pressure that could damage the fins. The object is to gently dislodge and wash away the debris and bugs, not to blast them into tiny pieces.
One other thought on radiators; keep in mind that often in RV applications, air cooled accessories are often "stacked", or there may be more than one cooling device stacked in front of the actual radiator itself. For example, a/c condensers, oil or transmission coolers, or on turbocharged engine applications, you may also have an "intercooler" or an "aftercooler" as well. In cases where there are multiple layers of cooling devices stacked, it is often a good idea to take them to a professional to have them "un-stacked" and cleaned, then reassembled. This assures you any build up that occurs between them is removed.
Let's also not forget the thermostat. This simple device is the very key to maintaining correct engine temperature, and if it opens too late, or too early, or never opens, or never closes, it can cause trouble. It is critical that the correct thermostat be used so that it warms up correctly, and operates within the manufacturers parameters.
Another important item in the cooling system is the radiator fan. These fans are designed to provide positive air flow over the radiator coils and fins to allow for proper heat dissipation, and should be checked regularly for damage to the blades or housing that might limit their efficiency. Radiator fans generally come in three different varieties. First is the good old fashioned pulley mounted, belt driven radiator fan. It may or may not have a clutch mechanism to regulate its speed, but either way, it just sits there and spins with the engine.
The second cooling fan, and currently most popular I the automotive world, is the electric fan. This electric fan is connected to a coolant temperature sensor, and turns on at a predetermined temperature. In most cases this fan is wired "hot" all the time (electricity is supplied to it all the time), and the coolant temperature sensor grounds against the engine block when the temp gets high enough, completing the DC circuit and turning the fan on. Once the coolant temp drops, the sensor looses it's ground to the block and the fan turns off. These fans are also wired to the vehicles air conditioning system so any time the A/C compressor is turned on (in air conditioning or defrosting modes), the cooling fan runs as well to help compensate for the additional work load being placed on the engine.
The final radiator fan is used most often on larger vehicles, like diesel motorhomes or large over the road trucks. Like the others, it uses a large fan to draw air through the radiator, but instead of a direct mechanical drive or an electric motor, this one is driven by hydraulics, and can vary fan speed (often regulated by electronics) to increase or decrease air flow across the radiator. A pump supplies pressurized hydraulic fluid to a hydraulic "motor" to spin the fan blades as necessary for the given load.
Don't forget to check those belts and hoses regularly as well. "Weather checked" rubber components that show signs of cracking or stress should be replaced immediately. Squeeze the hoses when they are cold; do they feel pliable? Do they feel mushy or otherwise compromised? Probably time to replace them. If in doubt, never hesitate to ask a professional. Sometimes 30 seconds of poking around can save you a break down somewhere on the highway.
Address any leaks you find immediately. Even some dampness around the end of a hose should be investigated and repaired as soon as you find it. Spots on the ground, or even a whiff of hot anti-freeze while walking around the unit is reason to investigate, even if the temperatures have remained normal in use.
Keeping your cool isn't always an easy thing to do, but with some knowledge of how your cooling system works, and some good old maintenance, you won't get steamed when you least expect it!
Enjoy your spring voyages around the country, and we will see you here next month!