Auto Service Professional

JUN 2018

Magazine for the auto service professional

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8 A S P J u n e 2 018 T e c h n i c a l Torque wrench maintenance If your shop follows proper threaded fastener tightening val- ues, your torque wrenches experi- ence plenty of use. Especially with regard to micrometer ratcheting "click" type torque wrenches, tool calibration can easily vary over time and use. Make a habit of having your torque wrenches recalibrated once per year in order to main- tain proper tightening values. Several recalibration service fa- cilities across the country offer this service. If in doubt, check with the manufacturer of your tools to locate this service. Sealing threaded plugs Whenever you're installing thread- ed plugs in an engine block, if the threads are tapered NPT pipe plugs, a thread sealant must be ap- plied to the plug threads before in- stallation. A PTFE or "Teflon pipe paste" can be used. If tapered threads are not coat- ed with thread sealant, the plug will not seal, regardless of tightening value. If the threads are straight, a sealing O-ring must be installed. is applies to plugs that seal water or oil. If a straight-thread plug is to be installed, be sure to lightly coat the new O-ring with oil prior to installation to prevent the O-ring from tearing. Spark plug blowout While not a common issue, if you ever run into a case where a spark plug has blown out of its hole on an aluminum cylinder head, chances are high that the fault lies with a poor aluminum casting, where combustion pres- sure overcame the integrity of the port threads, resulting in the spark plug being pushed out, tak- ing the female threads with it. Instead of replacing the cylinder head, the head can be saved by installing a special solid thread- ed insert. One source is Goodson Shop Supplies, which offers a complete kit (tools and inserts). While the repair can be per- formed on-the car (with minimal chance of metal debris entering the combustion chamber if in- structions are followed to the let- ter), the safe way is to remove the head to perform the repair. Re- pairing the faulty threads is not a difficult task, and will save the customer a substantial amount of money as compared to a new head replacement. Alternative to OE bolts When dealing with engine fas- teners where the tightening pro- cedure specifies a torque-plus angle method, always use new OE bolts. An alternative, if you prefer to avoid the multi-step tightening procedure, is to select aermarket performance bolts that specify a torque-only meth- od. Although not available for all applications, such performance bolts are readily available for main cap and cylinder head ap- plications, from sources such as American Racing Products. Such bolts are also re-usable. Fluid lines for the Rust Belt Metal brake and fuel lines, even those with so-called "special" coatings, tend to rust and rot on vehicles that are exposed to salt/brine road coatings in win- ter months. While slightly more expensive, an alternative is to use stainless steel lines, which can ei- ther be made to fit in your shop or ordered pre-bent to length, flared and equipped with the appropri- ate fittings, for most popular ve- hicle applications. High quality stainless steel lines should last the life of the vehicle. ■ From torque wrench maintenance to metal brake and fuel lines TECH TIPS Don't ignore your torque wrenches. Over time and with repeated use, calibration can wander. Make a habit of having your torque wrenches serviced and calibrated at least on an annual basis. If an OE torque-plus-angle is specified, current digital torque wrenches are readily available that offer both torque and angle modes, eliminating the need to perform angle tightening with a separate tool.

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