Featured Archives - Page 12 of 15 - UnderhoodService
Gasket Guide: Match A Sealant With Every Type of Gasket

Cork/Composite Gaskets Sealants: Cork and composite gaskets can seal a variety of underhood applications from valve covers to carburetors. The type of sealant used with these gaskets depends on a variety of factors. First, you must consider if the gasket needs to remain flexible. Second, you need to consider the temperatures the sealant will have

Clevite gasket
Saturn: Engine Does Not Crank, Dimmer Switch To Blame

Model: 2002 Saturn LW200, 2.2L Complaint The customer states the engine does not crank. Cause Confirmed the customer’s complaint and found the engine did not crank. Performed a visual inspection of the battery cables and found no obvious faults. Used a multimeter to measure the voltage across the battery terminals and found the measured voltage

Saturn dimmer switch
‘5 Checks’ Recommendation Simplifies Emissions System Diagnosis, Repair

Tenneco’s Walker Emissions Control brand is helping automotive service providers simplify emissions control diagnosis and repair through a variety of new educational tools, including a recommended set of five checks to perform before installing a replacement catalytic converter. These diagnostic checks are covered in a free technical video available through the “TennecoInc” channel at YouTube.com.

5 tips
Volumetric Efficiency Diagnostics

A few years ago, I obtained an OBDII scan tool/dynamometer simulation/calculation program that can graph volumetric efficiency (VE) over rpms. Using real world vehicles, and no useful instructions, I devised a test sequence that allows a technician to see things another way. What is Volumetric Efficiency? Let’s keep this simple to start. An engine is

Oil-Related Engine Codes for VVT Engines

Variable valve timing is becoming a standard system on most late-model engines because it offers higher performance from a smaller displacement engine at higher rpms. Oil plays a larger role in VVT systems. They need engine oil not only for lubrication, but also to actuate the camshafts to change the profile of the lobes. Oil

VVT camshaft adjustment
Harmonic Dampeners: Why They Fail, What to Look For

Every time a cylinder fires, the crankshaft speeds up a very small amount for a short period of time. It is then slowed down as the next cylinder in the firing order compresses air and fuel for the next combustion event. The speeding up and slowing down of the crankshaft produces torsional vibration or twisting

Harmonic Dampener
Be Careful When Replacing That Diesel Air Filter

Modern passenger and light-duty diesels with ECMs have mass airflow sensors and precisely control fuel ­delivery. Key to the efficiency and lifespan of the diesel engine is the diesel air filter. A restricted air filter will not affect fuel economy but will drastically affect power output. We asked prominent filter manufacturers for some diesel air

diesel air filter replacement gauge
Replacing a Faulty Ignition Coil

After a faulty ignition coil is diagnosed and replacement is determined, best practices are essential. Here is a list of tech tips when performing ignition coil replacements. • Coils shouldn’t have any visible damage and the boot should be fully seated. While assembling coils to the engine, disregard the coil if you notice any visible

Delphi Ignition Coil
Ford: Driveability issues due to water in the PCM

Some 1999-2003 Windstar and 2004-’07 Freestar /Monterey vehicles built prior to June 22, 2006, may exhibit engine/transmission driveability issues due to water entering the powertrain control module (PCM) or transaxle vent. The water leakage may be due to the PCM connector cover not seating completely and water leaking down from the cowl panel grille (cowl

Ford Taurus PCM
Top Turbocharger TSBs

In the past 15 years, turbochargers have ­become more common on all types of ­vehicles from 1.4L to 7.0L. These are the top TSBs to help diagnose the most ­common problems. Subaru: Inspect Oil Supply Before Replacing a Turbo Models: All turbo­charged Subarus TSB Number: 02-106-08R This TSB serves as a warning to technicians that

Turbocharger TSBs
Making Money with Mode $06

Nothing is more frustrating than “fixing” a customer’s vehicle and then have it come back a few days or weeks later with the check engine light on and the same fault code or a new fault code. You look bad, lose your customer’s confidence in your ability to fix their vehicle, and in states that

Mode 06 diagnostics
Must-Read TPMS Technical Service Bulletins

Here’s a rundown of the top technical service bulletins related to TPMS. These TSBs should be analyzed by every technician that services TPMS. Audi TSB Number: 4413382034445/1 Models: 2010-’14 A4/S4, A5/S5 and Q5 Summary: This TSB addresses TPMS MIL lights that are not related to a loss of pressure. The TPMS light may illuminate if