Auto Service Professional

DEC 2018

Magazine for the auto service professional

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D e c e m b e r 2 018 A SP 15 or torque only (if using aermarket bolts), check cra n k t h r ust /endplay w it h a d ia l i nd ic ator. Mount a dial indicator at the front of the crank, on the nose or the front counterweight face. Using a screwdriver as a pry bar, push the crank full rearward, then zero the dial indica- tor gauge. Next pry the crank forward using only moderate force. e factory OE specification lists a fairly wide range, from 0.0015-inch to 0.0078- inch. Ideally, crank endplay should be between 0.004-inch to 0.006-inch. When installing the new main bearings, in ad- dition to applying assembly lube to the upper and lower bearing faces, be sure to lube the front and rear thrust surfaces of the bearing shells, as well. Lee Delucia Fairmont Service KIA BRAKES I don't know if anyone else has run into this, but we recently serviced a 2015 Kia Soul. e owner complained of a "noise" in the rear. During in- spection of the rear disc brakes, one pad had the lining completely gone (metal to metal). Both rotors were rusted because the pads were so badly stuck in the caliper brackets that they couldn't move. We had to beat the pads out with a hammer aer we removed the brackets from the car. e old pads and even the new pads seemed to be extremely tight in the brackets. We filed the ends of the pad backing plate tabs a bit to free them up for a proper fit. Matt Sweeny Universal Undercar Service UNDERSTANDING FUEL TRIM is may help new or apprentice technicians who may not be familiar with fuel trim. ere are two types of fuel trim, long term and short term, and the numbers are displayed on the scan tool as a percentage of fuel added to or subtracted from the pre-programmed fuel quantity. Volkswagen calls fuel trim "oxygen sensor adaptation," and Ford classifies fuel trim as a "continuous monitor" that runs when the fuel control system is in closed loop operation. is shows us that fuel trim is an ongoing calculation based on data reported by the oxygen sensor. Extra oxygen in the exhaust indicates a lean air/fuel mixture, so the PCM increases injector pulse width to add more fuel (positive fuel trim). Too little oxygen in the exhaust indicates a rich mixture, causing the PCM to reduce injector pulse width (negative fuel trim). e formula for fuel trim calculation is: • Fuel mass = air mass x (short term fuel trim x long term fuel trim) divided by (equivalence ra- tio x 14.64). Understanding these terms and their rela- tionship will help you understand how to use fuel trim data shown on a scan tool. Ed Gregaria Allstar Diagnostics & Repair Service technicians share tricks of the trade from Techs' After installing a new thrust bearing, lightly knock the crankshaft fore and aft with a brass hammer before torqueing the main caps. This will aid in squaring-up the thrust bearing cap. Using a dial indicator, push the crankshaft rearward and zero the indicator gauge, then push the crankshaft forward to observe the amount of crankshaft endplay.

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