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Identifying Tractor Smells
We are continuing our series on learning to talk the language of our tractor. Since we canít actually talk to our tractors, though some of the older sect of farmers might disagree, we use our five physical senses to observe and construe what our iron age friends are trying to tell us. We have already talked about some of the colors the unit might leave as clues to its well-being. Now we are going to use our noses to diagnose particular smells.
While bushogging in the back field one year some rather large bushes forced some wiring to come in contact with the fan belt pulley. After a little time the wires rubbed through the wire insulation and shorted against each. An odor similar to leaving a milk carton on the stove roiled around the tractor seat. The smell of cooking plastic prompted me to shut off the tractor, quickly disconnect the ground cable from the battery and look for the problem.
Electrical odors can be the most dangerous of tractor smells. A hot wire grounding to the frame or another circuit can flash melt an entire wiring harness in a matter of seconds. If the shorted wires are near a fuel line the overheated wires can burn through a rubber gas hose and ignite the tractor. Similarly they can ignite a fluff ball of milkweed pods stuffed under the radiator cowling or a ball of oil soaked grass wedged behind the steering box or under the battery plate. It is important to recognize the particular odor that this threat puts out. Since the smell is actually the plastic insulation melting and/or burning off of the copper strands of the wire the characteristic odor is almost the same as what a plastic bottle in a burn can would smell like. Another example would be the hairdryer that your daughter or wife overuses in the morning. That particular odor is a marker to shut off the tractor and look for problems. If possible always carry a battery wrench in your tractor tool box and quickly disconnect the negative battery cable end from the terminal post in order to minimize the damage potential.
After I got the tractor shut off I was able to locate the errant wire by looking for obvious wire rubbing and then checking the wire casing for rub-throughs. In many cases by the time the battery gets disconnected the wire has already done a job of melting the insulation. By tracing the melting to the furthest point away from the battery the bad spot can usually be identified. Look for rubbed wires against metal or places where the wire has crimped back on itself or even melted though another crossing wire. Also look for wires that pass underneath fixtures like the radiator or cowling. Sometimes a bushing will wear out and cause a fixture shift which will crimp or crack a wire.
One of the most prominent odors is an overheated engine steaming out antifreeze. Just about everyone is acquainted with the sweet, syrupy smell that boiling coolant gives off. Usually it accompanies a broken radiator hose or a rusty radiator cap that has lowered the coolant pressure enough to let antifreeze pour over the fan and onto the rest of the engine and, from there, onto the operator. It is really handy to recognize the antifreeze smell before the soaking occurs. The smell is characterized by a sweet almost sugary odor. When noticed the tractor should be shut off and the leakage spot determined. Look for pin holes in the radiator and/or corresponding hoses, the cap, overflow tube, or water pump bushings, seal, or gaskets. Check the temperature gauge to see if the leakage is a result of overheating or a potential cause for overheating.
Fuel smells, like electrical, can be a serious hazard if not located and repaired. Other than a result of spillage during tank fillage or a case of severe engine flooding, there should be no odor from diesel or gasoline fuel systems. A strong fuel odor is characteristic of a leaking fuel pump, a broken fuel line, or a leaking fuel tank. Other sources can be an overchoked carburetor filling the air intake line with raw gas, a leaking fuel injection pump, or loose injector. Loose fuel in the wrong places can rapidly turn to vapor on a hot engine and be ignited by hot exhaust manifolds, sparking distributors or loose exhaust pipes which spit sparks. Take care not to operate the unit with stray fuel leaking out.
Another of the more common smells is that of burning oil. This odor is quite similar to burning cooking oil on an overheated iron skillet. It seems to show up the most from the bottom of leaky valve covers, with the dirty oil dripping down on the exhaust manifold. The oily aroma is potent and easily smelled, especially when the tractor is shut off....the smell just kind of lingers. Replace the gaskets under the leaking part before the oil residue builds up and creates a hardened oil crust which is unsightly, collects dust and dirt, and is really difficult to clean off.
All of the above smells are indicative of relatively cheap repairs. Unfortunately, because they tend to be cheap, they never get fixed. On the other hand when the aroma of burning high temperature friction discs crosses onesí nostrils immediate attention should be done. The smell can be easily associated with that of overheated truck brakes on a narrow mountain road or that of ones son or daughter trying to get manual transmission car out of a snow bank for the first time. Unlike the smell of oil or possibly antifreeze, it is wise to discontinue activity as soon as the odor comes to the driverís seat. Internal brake discs and friction clutches are not only expensive but are hard to get to and the associated pressure plates and flywheel surfaces can often be damaged by the excessive heat buildup. Take care to find give adequate cool off time for the discs before trying to resume the activity.
Taking the time to acquaint oneself with the assorted odors that a tractor gives off can be very beneficial to extending the lifespan and service time of your unit. Tractor odors can be the first line of defense for catching problems before they occur because one doesnít have to actually isolate and see the problem. The particular smell can catch ones attention while watching a bushog or can be a definitive identifier while working at night or under inclement conditions. These odors are yet another way of learning how to communicate with our old iron....maybe those older farmers knew something after all....