Diagnostic Tricks

Dan Anderson

11/4/2008

Repairing broken equipment is a feat in and of itself, but finding the root of the problem is often more difficult than fixing the actual problem. Here are a few tricks, shortcuts and gadgets to help determine the origins of mechanical maladies.

--Single V-belts that overturn in their pulleys and run upside down or multigroove V-belts that jump off one side of their sheave are symptomatic of misaligned pulleys or sheaves. Use a straightedge or string line to check alignment before installing new belts.

--To pinpoint a minuscule leak on hydraulic components, first clean the accumulated glop off the area with compressed air. Then, clean and dry it with contact cleaner or brake cleaner. Toss a thin layer of talcum powder or flour onto the area. Activate all hydraulic functions, run the machine through all hydraulic cycles, then shut it off and look for discolored areas of talcum or flour. The super dry white powder will magnify even minute traces of oil and pinpoint the source of the leak.

--If a planter, baler, field cultivator or other drawn implement seems to have a hydraulic problem, first switch the hoses to a different pair of hydraulic outlets on the tractor. If the system works correctly then, the problem is in the tractor’s hydraulic coupler block, not the implement. Many, many hours have been spent futilely chasing gremlins in implement hydraulic systems that were actually in the tractor’s hydraulic couplers.

--When warning messages appear on display screens of auto-steer, GPS, planter, yield or other computerized monitors, write down the warning message, then shut off the machine for 30 seconds. Restarting computerized systems often clears the problem. If not, begin the diagnostic process in the owner’s manual.

--On older diesel engines with mechanical fuel-injection pumps, plugged or malfunctioning injectors can often be identified by feeling each injection line while the machine is running. The line that “pulses” differently from other injector lines is the line to the faulty injector. A messier test is to crack a fitting on the injection line leading to each injector while the engine is running. But be careful—the fuel is under extreme pressure. The engine will misfire more when good lines are cracked; cracking the fitting to the faulty injector won’t change the engine’s tune because it’s already misfiring on that cylinder. (These tests won’t work on modern electronically controlled fuel-injection systems.)

--On malfunctioning equipment with electric solenoids that control hydraulic valves (spray boom shutoffs, boom raise/lower valves, combine header control valves, etc.), use a small screwdriver to test for magnetism on the end of the solenoid when the system is activated. If the solenoid is magnetized, the electrical side of the system is working properly and the malfunction is in the hydraulic side of the system. If the solenoid isn’t magnetized, the glitch is in the electrical system. No use tearing apart the hydraulic system if the problem is an electric control switch in the cab.

--An electrical system that works at start-up but kicks out after the machine has run for a while hints of a faulty relay or weak circuit breaker. Locate the circuit breaker/relay for the faulty system. If it’s warmer to the touch than nearby breakers/relays, switch the hot one with one of its cooler neighbors. If malfunction follows, replace with a new one.

--Cell phones, FM business radios, satellite radios and other high-tech gadgets can affect GPS, auto-steer, mapping and other features in modern equipment. Note if odd, intermittent failures coincide with their use.

--Rather than drain a hydraulic reservoir, fuel tank or radiator to make minor repairs, duct tape the suction hose from a shop vacuum to the fill tube of the reservoir. If there are no other vents to atmosphere, running the shop vac will pull enough vacuum to hold the fluid in the reservoir while replacing hoses, O-rings or gaskets. There will be some leakage but not a flood—unless someone happens to turn off the shop vac in the midst of your repairs.


Cool Tool of the Month:

For farmers, buying complete sets of ¼", 3⁄8", ½" and ¾" sockets for the shop and the work truck would cost a fortune. For $35, this rack of socket adapters from Mac Tools (catalog number SAD6T) will allow a few sockets to do the hard work of many.