Cooling farm machines in hot climates.

An Israeli mechanic explores the idea that a product, such as a tractor radiator, designed to work in one corner of the world or even one corner of a country, may not work as well mechanically in another part of the world.

The temperature difference between the ambient temperature and the working machine temperature dictates the amount of cooling power necessary to control a steady machine temperature between 85-95 [degrees] C. In a cold climate, heat retention can be achieved with smaller radiators, routing the transmission lubrication through the engine radiator to accelerate the machine response. However, a machine that works well in cooler climates can be a disaster in a hot climate because of insufficient radiator size.

In Israel, with temperatures exceeding 30 [degrees] C (86 [degrees] F)for as long as eight months, the problem is how to get rid of heat. The design suitable for a cold climate becomes an obstacle here - it causes the cooling system to work most of the year at its highest capacity. Here, 80% of repairs are related to overheating problems.

Various conditions in the cooling system - external clogging of the radiator by dirt, cotton, straw; internal clogging of narrow radiator passages; low coolant level resulting from leakage; a worn-out motor - any or all of these will cause more heat radiation and lower efficiency. Any delay in handling these conditions can cause expensive motor repairs.

Why should tractor manufacturers care about our cooling system problems?

First: Tractor production for export provides US and England with a sizable percentage of its income. Understanding how hot country consumers suffer from design producers' insensitivity to hot temperatures can lead to a better product.

Second: Using devices like quality temperature gauges for overheating in your short hot summer can help over come difficulties of underheating in a longer cold climate.

Third: The globe is getting hotter - be ready!

Searching for solutions

Awareness of the problem is a big part of the solution. For the past six years I have searched for a technical, efficient, inexpensive, and trustworthy way to make our machines immune to overheating. Various experiments were performed with accurate thermometers - change of location of heat exchangers; separation of heat exchangers; enlargement of a different type of heat exchangers in relation to different fans.

Results came fast. We found that overheating problems can be taken care of with a three-part solution:

1. Using digital thermometers for accurate readings of engine heat.

2. Separating (or adding) different heat exchangers from the engine main heat exchanger to facilitate the intake of Cooler air by the main radiator, which also provides easier access for cleaning and maintenance purposes.

3. Increasing the cooling power of the main radiator and/or increasing the air flow for additional cooling.

Clearly, these three steps express the gradual investment in parts and in work required for best results at least expense. Machines whose sensitivity to heating up was a daily problem now work normally even in hot desert wind conditions in dusty feedlots areas, with attention given only to regular interval oil changes.

I have not yet tried to solve our overheating problems with a bypass radiator. It is an appealing idea, but finding unusual size radiators is hard.

Developing thermometer reliability

An accurate, reliable thermometer is the first requirement in dealing with a cooling system. Lack of exactness in some of the measurements of degrees make it difficult to identify and deal with a small temperature change.

A change large enough to draw attention may be noticed too late. When coolant escapes from the system as a result of a rubber hose failure, the regular heat gauge ceases to show heat readings because the sensor unit no longer is in contact with the fluid. At such a critical moment, when there is no monitoring of the engine's rising temperature, the results are apt to be catastrophic.

The digital heat gauge today on the market is more exact and trustworthy than ever. It is equipped with a viewing screen that shows clearly and in time individual degrees and heat changes. It is not dependent on being immersed in fluid in order to give a temperature reading. The engine casting conducts heat and feeds the sensor. The connection point of the sensor is at the rear of the engine head, which is the first to suffer from overheating because the cooling failure first affects the part furthest from the radiator and water pump.

It is possible to insert the sensor into an unused hole made by a screw, and so also possible to pull out the water expansion plug and braze 1/4[inches] plugged pipe for the sensor. The sensor wire can be extended as far as one wishes. The gauge contains within it a relay or two, as ordered, so as to activate alarm or the fan. Furthermore, such a heat gauge senses the exact temperature through the cast iron.

Primarily, the role of coolant is not to cool, but to provide a means by which to keep watch over the heat of the engine. Put simply, even if much water is lacking, the heat gauge sends out a warning before damage is caused.

Remember: the coolant is only an important device - not the object. The object is to keep engine temperature within the limit.

Installation of such a heat gauge enables a non-technical person to keep careful watch over engine heating. Temperature degree numbers are large, clear, and change the instant a problem arises. Its exactness safeguards an engine by providing an understanding of what is happening - which is definitely more important than an unexplained alarm warning or engine breakdown.

Separating heat exchangers

To ensure normal heat performance, frequent urgent maintenance of radiator cleanliness becomes bothersome after several hours. A machine equipped with a transmission lubricant heat exchanger in the radiator or with an air conditioner has a big source of heat production no less than that of a dirt-stuffed radiator.

It is strongly advisable to install these radiators in a location for easy access, on hinges and with an additional electric fan. This makes it significantly easier to clean the main radiator and extends the maintenancefree periods. The recommended location is either the side of the tractor or above the engine.

Bear this in mind: separation between radiators is not a magic solution for the mechanical reason for engine overheating. Failure can be caused by a blown head gasket, excessive internal moving parts friction, plugged internal coolant passages in radiator, or too small a radiator.

Increasing Cooling Power

This step is the most expensive and intricate of all the procedures described so far and should be done only after the previous steps.

Before increasing cooling power, three determining factors should be taken into account.

* Air Flow. Air flow can be improved with the aid of an electric fan operated by a thermostat relay. In machines like field forklifts, the cooling power of the fan runs down because the engine RPM doesn't create enough air current past the radiator. Sometimes the addition of just one electric fan thermostat control solves the problem.

* Size of radiator. A big change in the cooling mechanism is more complex. Such a change requires a physical space not always available under the engine hood. Additional rows to the radiator will not necessarily dispel heat, as they heat the other ones and reduce the cooling efficiency of the radiator.

Therefore, it is better to change to a bigger radiator surface in two ways:

1. If there is no room under the hood for a bigger radiator surface and the radiator is hard to get at for inspection or cleaning, there is the option of moving the entire radiator outside, enlarging it to the right size and cooling it down by one or more electric or hydrostatic fans. This solution works successfully.

2. If in both cases (under the hood and outside), there is not sufficient space for a bigger radiator surface it is advisable to split the cooling power by attaching a smaller radiator in parallel to the main one with a thermostatically operated electric fan.

* Amount of coolant. The amount of coolant circulating can be changed by a bigger circulation pump. This is a more complicated change. I had good results from manipulating radiators size and location.

RELATED ARTICLE: Electric Fans

More electric fans are put on radiators today than other air blowing device system - the outcome of a silence revolution on vehicles in the last 15 years. Their size, efficiency, price, and reliability keep them a leading device in automotive industry. Fans are defined by size and amount of air they can blow.

Narrow dimension fans can reach up to 30-40 cm. and consume 7-8 amp. Experience shows that fans with smaller diameters (20 cm.) have better survival ability. Thus, an arrangement combining two small ones will do better, despite the diappointing fact that the price of small and large fans are the same. Another bit of advice: choose the push type blower because cooler incoming air extends blower life!

Wide dimension fans have high velocity power, strong motors with aggressive fans, and fan hosing patterns which reach 30 cm. in diameter and consume 37-40 amp. They can be assembled with a two-speed device to ease the load on the electric system.

RELATED ARTICLE: Digital thermometer

This device is a small processor, translating low voltage changes into digital and back. It is fast, responsive, accurate, reliable, and gives enough time to see any changes in temperature.

A big advantage is that the sensor wire can be extended as far as necessary and easily inserted into an empty thread hole or brazed to the expansion plug at the rear of the engine head. The biggest benefit is that the sensor does not need to be immersed in the coolant in order to show true temperature reading. In the event of coolant escape and no control on temperature rise, the unit also contain one or two 7A relays for an alarm or blower.

Doron Yoffe, a mechanic at the machine shop complex of kibbutz Ramat Yohanan, Israel, can be contacted by phone: [phone]; fax: [phone]; e-mail: doyoffe @carmel. zvulun. k12. il.