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Strange Requests At The Service Counter

Sometimes, I have to wonder if certain ­customers’ brains are firing on all cylinders. But as an automotive service professional, I have to maintain a certain level of self-control while answering their questions, even though what they’re...

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Are All Cars ‘Supercars’ Now?

I attended an open house at Smokey’s Dyno in Akron, Ohio, last month. The shop was filled with Lamborghinis, Jaguars and other high-end cars. It was a great chance to look under the hoods of some supercars. The shop even had a rare McLaren P1 sitting...

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Documenting Inspections: Are You Leaving Maintenance Dollars on the Table?

How do you translate scribbles on a ­repair order into sales? There is no magic trick involved — the key is to document the vehicle ­inspection process. The more you know about your customers’ vehicles, and the more you are able to document...

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Mazda: Performing Regular Undercar Maintenance

This month, we’ll take a look at brake and undercar service on the Mazda vehicle lineup, with the footnote that even though this type of work ­becomes routine when you have a preventive maintenance mindset, good work habits from beginning to end are...

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Import Automatic Transmission Diagnostics

Don’t be alarmed if you pull an automatic transmission trouble code when diagnosing a “check engine” warning light! Since the automatic transmission operation has a major effect on grams-per-mile exhaust emissions, you’re going to see the...

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Honda: Vehicle Won’t Move or Barely Moves

A customer brings in a vehicle that won’t move forward, ­­backward or both. Check first to see if it grinds or clicks. And does the speedometer read a lot higher than you’re actually going? Chances are the driveshaft is disengaged. This can...

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TPMS Service Tip: Ask the Right Questions

If there is one piece of major advice for any tire tech facing a TPMS issue, it would be this: Test before you touch, and document the answers you get. Understanding the potential TPMS land mines can save time and money and eliminate frustrations. Get...

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False ABS Activation After Wheel Bearing Hub Replacement

Vehicles: All ABS-equipped vehicles Condition: Vehicle had wheel bearing hub replaced on one side. Repair Procedure: If you diagnose a bad hub bearing on one side of a vehicle and the ABS wheel speed sensor or tone ring is integral to the bearing,...

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Are you afraid of selling alignments?

I am starting to notice a trend when it comes to alignments. It’s not the vehicles that are changing, but rather the attitudes toward alignment services — and it happens at independent repair shops, franchise shops and even dealers. The alignment...

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iATN Exceeds 2 Million Forum Messages

The number of messages in the professional automotive discussion forums of the International Automotive Technicians Network (iATN) exceeded 2 million in early December 2014, with the Shop Management and Technical Discussion forums being the most popular...

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Diagnosing Starter Misses

Contributing writer Gary Goms was called to a friend’s shop to help with a no-cranking condition on a 2006 Chevy Tahoe. After diagnosing a faulty PCM ground, locating the missing ground proved to be problematic. Find out how Gary solves The Case...

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Snap-on Adds Diagnostic Calculator To Website

Snap-on announces a new diagnostic calculator feature has been added to its website at http://diagnostics.snapon.com to help automotive repair technicians and shop owners determine how much profit they could be making by using a Snap-on diagnostic platform,...

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Home Cooling Tech Feature: Straight Up Look at the Vortec 3500 Straight-Five Engine

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these engines are interference engines with tight valve-to-piston clearances, so accurate cam timing is absolutely essential. The cam phaser on the front of the exhaust cam can retard exhaust valve timing from 0 to 25 degrees.

At idle, it is in the fully advanced position, and must be installed in this position to prevent the exhaust valves from hitting the ­pistons.

Changing the timing chain requires using a J44221 Cam Holding Tool (or equivalent) to keep the cams from moving when the chain is taken off.

The basic procedure is to remove the intake and exhaust cam position sensors, remove the front cover, rotate the crankshaft so number one piston is at TDC (top dead center), install the cam holding tool, then release tension on the timing chain by moving the tensioner shoe in.

idle problems caused by dirt or fuel varnish in the throttle body can be removed with throttle cleaner. Use a tee to lock the tensioner in place, remove the cam phaser from the exhaust cam, then the sprocket from the intake cam, and finally the crank sprocket (all three sprockets should be replaced along with the timing chain).

Every seventh link on the timing chain is darkened to aid in aligning the timing marks. After installing a new sprocket on the crankshaft, align one of these marks on the chain with the mark on the sprocket (which should be at the 5 o’clock position).

Align another dark link on the chain with the timing mark on the intake cam sprocket (1 o’clock position). Then install the cam phaser on the exhaust cam. T

he word “Delphi” should be level and parallel to the seam on the head, and the cam phaser must be in the fully advanced position. Align another dark link on the chain with the mark on the exhaust sprocket (which should be at the 11 o’clock position).

Remove the tee from the chain tensioner and make sure all of the timing marks are correctly aligned.

starter icing issues eliminated — the vortec 3500 is fitted with a new vented starter solenoid. the solenoid case has a micromesh-covered vent that protects the solenoid from debris particles but prevents moisture buildup. when the engine is warm, any moisture on the solenoid evaporates through the vent. the vented solenoid virtually eliminates the possibility of cold-start problems associated with solenoid icing.Sensors
These engines use a single magnetic crank sensor mounted in the block near the back of the engine, and a pair of camshaft sensors mounted in the front of the cylinder head to monitor crankshaft position and cam phasing.

If the crank sensor, either cam sensor or the PCM (Powertrain Control Module) on one of these applications has to be replaced for any reason, you must perform a CKP System Variation Learn Procedure using a Tech 1 or similar scan tool.

It’s the same procedure that’s required on many other GM engines so the PCM can learn the relative positions of the crank and cam sensors. If the procedure is not performed, the engine may not run properly or may not start.

The 2004 version of the 3500 came with two knock sensors. Knock protection was deemed critical on these engines because of their high compression ratio (10:1) and use of regular 87 octane fuel.

But improved PCM programming allowed GM to discontinue the second knock sensor in 2005. The remaining knock sensor is located on the left side of the engine between cylinders number 3 and 4.

Inputs for fuel management are provided by a mass airflow (MAF) sensor mounted ahead of the electronic throttle body, a manifold absolute pressure (MAP) sensor on the intake manifold and a throttle position (TPS) sensor on the throttle.

A buildup of dirt or fuel varnish on the MAF sensor may cause lean codes to set. Cleaning the MAF sensor with aerosol electronics cleaner can often correct this kind of problem. Idle problems caused by dirt or fuel varnish in the throttle body can be removed with throttle cleaner.

Maintenance
Starting in 2004, the recommended oil for the 2800, 3500 and 4200 engines is 5W-30 that meets GF-4 specifications. The crankcase oil capacity is six quarts.

GM uses its Oil Life Monitor System on these applications to indicate when it’s time to change the oil.

Based on vehicle usage, temperature, run time, vehicle speed, load and so on, the estimated oil change interval may vary from as little as 3,000 miles to as much as 15,000 miles.

We think pushing the oil change interval much beyond 7,500 miles with any oil other than a top quality full synthetic is asking for trouble.

The Chevy Colorado and GMC Canyon both have conventional fuel filters located outside the fuel tank that can be replaced on an “as needed” basis. GM offers no recommended service interval for the filter.

The serpentine belt likewise has no recommended replacement interval. Most belts are good for 100,000 miles, but need to be inspected to check for wear and proper tension. Belt noise and/or accelerated wear can be caused by pulley misalignment. GM TSB 08-06-01-006A says to use a laser pulley alignment checker if you suspect belt noise or wear may be due to misalignment of the power steering pump pulley.

The original equipment spark plugs have a 100,000-mile replacement interval (gap is 0.042”).

Inspect the engine air filter every 15,000 miles and replace as needed. The Chevy Colorado and GMC Canyon are not equipped with a cabin air filter.

The Dex-Cool coolant is a five-year/150,000-mile coolant. Most trucks will reach five years before the odometer hits 150,000 miles, so recommend changing the coolant after five years of service. Waiting longer increases the risk of damaging coolant corrosion and expensive cooling system repairs. 

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Larry Carley

Larry Carley has more than 30 years of experience in the automotive aftermarket, including experience as an ASE-certified technician, and has won numerous awards for his articles. He has written 12 automotive-related books and developed automotive training software, available at www.carleysoftware.com.

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