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Tuning Up Your Tractor (Part 4)
Our tractor is coming right along. The old oil and filter has been taken to the recycler and the air filter replacement has breathed new life into our motor. Let's take a closer look, now, at the cooling system since it has to work so hard in the summer heat.
Cooling systems can be real cantankerous in their old age. Radiator cores clog up with rust, lime or other mineral deposits and the fins clog up with weed seeds and debris. The metal headers slowly corrode away from years of use and the seams seem to always be moist with residual antifreeze. On hot days the radiator cap bellows out a stream of steam and reminds one of an old model T along side the road with an overheated engine. So how can we recognize potential problems and catch them before they happen?
The radiator, usually at the front of the tractor, is a good place to start. Check the front and rear for a build up of bugs, seeds, and weeds from the pasture. Water from a garden hose sprayed from the fan side of the radiator will remove a lot of the built up debris. Next check for moisture around the radiator core and headers. If there is leakage it will be moist and smell sweet. If ther is leakage it would be wise to have the radiator professionally flow tested and checked for lime buildup and core leakage. Next, remove the radiator cap and inspect its bottom. The cap is designed to raise the pressure in the cooling system so the coolant boils at a higher temperature. Each pound of pressure raises the boiling point by 3 degrees. A six pound pressure cap would raise the boiling point of the coolant by eighteen degrees, or from 212 degrees to 230 degrees. Make sure and check the manual for the proper pressure cap as one that is too high has a tendency to blow hoses and radiator cores. The bottom of the cap should be clean and must fit snugly onto the filler neck. Check the rubber bottom for swelling, nicks, or cracks. Also check the brass filler neck for uniformity on the sealing surfaces. A warp or hairline crack will cause pressure to leak out when in use.
Before continuing with our antifreeze inspection it is wise to check all the cooling system hoses. Hoses that are hard, brittle or cracked need to be replaced. On other hoses look for small patches of moisture on the hose surface and then gently knead that area and hunt for a hairline crack or pinhole. These areas tend to leak only when the tractor is at operating temperature and under pressure and can be difficult to notice. When leaking, though, they can shoot a hair-sized stream of hot antifreeze onto electrical parts and cause engine misfiring. Look for hoses that have swelled up because of oil contamination. They feel greasy and spongy when kneaded. Replace any hoses that are marginal. It's good to change the hose clamps also as dirt and grit can make them hard to properly torque. Also make sure and purchase the correct hose size. A hose that is too big or too small will only cause problems at a later date, especially if a sealing compound like silicone is used to try to water tighten a connection.
Antifreeze, nowadays, is a mixture of ethylene glycol and water. It used to be a mix of ethyl or methyl alcohol and water. With technological advances and different sealing compounds along with higher engine temperatures the alcohol mix became antiquated as it would evaporate or not provide adequate internal part protection in regular use. Pure ethylene glycol works as a catalyst when mixed with water. In its pure state it freezes around nine below zero but when mixed in proper proportions with water it will provide protection up to 50 or so below zero. In addition to freezing protection the solution provides a chemical soup of internal engine protectors. It contains a rust retardant, particle suspension compounds, a lubricant for the water pump seals and bushings, and corrosion resistors. When these chemical compounds wear out the antifreeze will change color and/or get cloudy. A rusty antifreeze color, for example, means that the rust inhibitor has lived its useful life. Examine the color of the antifreeze compound in the unit you are inspecting. It needs to be a clean and green. Take a temperature tester and see what the freezing point is. If the antifreeze has been in the unit for more than three years it is a good idea to replace it. Changing the stuff isn't that big a deal. Drain the radiator contents into a container. Make sure not to spill any because the dog will love the sweet taste but it is highly toxic if ingested. Also find the drain cock on the side of the engine and drain the extra few quarts out of the block. Re tighten the block drain and refill the radiator with fresh antifreeze and, preferably, distilled water (this will reduce mineral buildup over time since it is relatively mineral free).
If working on a budget, like most of us do-it-yourselfers do, you might consider filtering out your old antifreeze. I made a filter out of some gravel, coarse sand, filter paper and cotton. It took a while for the solution to filter but when it came out the other end it looked great. But don't stop with just the filtered antifreeze. Get some litmus paper to see what the acidic content is and then get some antifreeze suplement at the auto store. This stuff has the additives in a mix that can be added to the old filtered antifreeze that will give it some additional lifespan. Like I said, it is a budget measure.
Time to check the belts on the engine. Most tractors will only have one, at most two belts. They usually run the fan/water pump assembly and generator. Grasp each drive belt and roll it around so that the bottom and one side are clearly visible. Look for signs of cracking, oil soaking, hard glazed contact surface, splitting or fraying. Replace any belt showing these signs. Make sure when installing new belts or when retightening old ones to get the correct belt tension. A belt too tight will cause premature wear on the bearings; a belt too loose will squeal, flap, and cause other unit problems.
One last tidbit to check on this section is the fuel filter. This often neglected item can cause no end to an engine running funny. When plugged it will lean out the fuel mixture and cause backfiring, spitting, and misfiring. When the engine dies back pressure from expanding vapor from the fuel pump will push debris from the filter back into the tank and let fuel flow freely....for a little bit. The engine will start up and run like normal until debris, once again, finds its way back into the filter element. If suspect, replace. It is a very low cost item. Also check the fuel hoses, if rubber, for kinking, pinching from tight bends, or internal swelling due to using a hose that is non compatible with gasoline. Also check to see if a fuel line is running near an exhaust manifold or pipe. The extra heat will sometimes cause a vaporizing problem on hot days where the fuel will turn to a gas in the line and cause the fuel circuit to 'vapor lock', or stop delivering fuel to the carb. If this happens a wrapping of aluminum foil around the fuel line and attached with bread twisties will reflect the radiated heat and help alleviate the problem.