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Why Change a Timing Belt?

Gear case (3)Hands down this is the most important service to be performed on a vehicle. The timing belt is the main toothed belt that keeps the crankshaft and camshaft sections of your motor synchronized. Did you know that 18% to 30% of the crankshaft power goes through the timing belt to operate the valves? If allowed to get too old, the timing belt will crack and eventually break, causing thousands of dollars in repairs to the engine, and sometimes requiring engine replacement. Many older vehicles have not been kept to the scheduled timing belt replacement intervals and it is up to the owner to ensure it is changed before it breaks. Gone are the years of the “non-interference” motor where the piston could go over the top and not hit an open valve if the timing belt broke. And that is good, since all of those motors were quite inefficient compared to their modern cousins, the interference motors. Motors from last century only used 18% to 22% of the fuel to make power. The rest dissipated in heat through the exhaust and coolant. Modern motors are closing on the 30% mark. A strong statement on mileage versus horsepower.

When To Change The Timing Belt

Most Audi and VW models should receive a timing belt replacement between 60,000 and 90,000 miles. The 1.8 Turbocharged engine belt replacement is at 5 years or 75,000 miles, and the time factor is critical because of the high engine compartment temperatures. And these were among the many engines that the factory specified an interval of 105,000 miles originally. Until a high percentage of them failed early. Ever since the 80’s, dealers have publicized high mileage timing belt intervals to improve their JD Powers ratings to help sell the cars, only to reduce the interval later once they were out of warranty. Some motors since 2005 have great improvements to their timing belt systems that should allow them to exceed 100,000 miles. Do you feel lucky? Better belt construction, oblong crank gears with variable tooth spacing, and balance shafts all contribute to longer timing belt lifespan. At Karmakanix, the timing belt is checked every time your vehicle comes in for a major service to make sure of its condition. Pre Purchase Inspections also include this checkup.

What To Change With A Timing Belt

Every timing belt job should include all the rollers and the tensioner, and a water pump if applicable. The factory recommends replacing all these parts with a timing belt. Our standard tasks for timing belts include accessory drive belts, or serpentine belts, and their tensioners. If these drive belts and/or tensioners have been done recently enough, we will delete the parts from your bill. Generally the timing belt rollers and water pumps are not designed to make it through the life of two timing belts. Only the top quality components should be used. In most cases, we buy water pumps from the dealer, as our experience shows that aftermarket pumps regularly fail after just a few years. We also test each new roller and tensioner before installing it, as we find a small percentage of them feel “lumpy” and might fail early. The cheap route of just replacing the belt can instantly turn much more expensive if an old component fails. At least, the job must be done again. At most, all the valves get bent or the engine is destroyed. Lo barrato sale caro! Call us if you are uncertain about how old the belt might be on your motor.

Be aware that many brands of timing belts are available with many countries of origin. We have seen a couple of brands that look like scaly alligator skin at just a few years old. Continental and Dayco are both acknowledged as the top of the field. Do not risk your motor to an inferior brand of timing belt.

Tools for Timing Belts: An Absolute Necessity

Starting with the diesel motors of the 1970’s, special tools are required to perform a timing belt job on most motors. This includes all the Vee configuration motors such as a V6 or a V8, and every diesel ever made. The last exception was the 1.8T motor which ended in 2005. All modern 4 cylinder engines have their own batch of required tools. The required tool list typically includes crankshaft locks and camshaft locks, and an assortment of tools to turn the tensioners. Early diesels require a dial indicator and adapter stand to set the injection pump timing, Tdi diesels through 2003 require that the timing be set with a computer. The required tools for timing belts are necessary because the belt timing of the camshaft to the crankshaft involves a cam gear that fits on a taper and precisely sets the cam timing to within less than one degree. This is essential for full compression and power, for efficiency and mileage, as well as cylinder balance on a Vee motor. Understand that these tools are also required any time the timing belt is disturbed for water pump replacement.

Audi V8 Timing Belt ToolsMany internet do-it-yourself articles would lead you to believe these tools are not required, saying that the cam timing will be perfect if you just mark the belt gears and pulleys with paint and install the new belt. And some shops actually do just that. The result is an engine with poor power and mileage, and it can overheat and vibrate while driving. Sometimes the cam timing is left so off kilter that the engine computer detects the issue and generates trouble codes and turns on the yellow Check Engine light. Occasionally all the valves get bent during the experiment and seriously expensive repair is required.

Karmakanix has every factory tool required for timing belts or chain jobs on every engine we work on. When a new engine comes out, we gear up for the timing belt or chain job. All critical nuts and bolts get hand torqued with torque wrenches. All settings get checked and reset, including those that require a computer and software to communicate with your engine’s computer. The front of the car is removed on many cars, and we make sure no paint gets damaged, and all parts align perfectly.

Some engines have options for timing belts for quality. Kevlar reinforced belts with Teflon coated teeth cost more, but last longer. Tensioners and rollers come in different brands and qualities. Karmakanix only uses the top quality parts. We see no reason to go cheap and compromise reliability.

Timing Chains

Please note that some motors have a timing chain system instead of a timing belt. Only a Vanagon has no timing belt or chain. A short list of chain motors includes: Most Porsches. The Volkswagen VR6 engine; that was first offered in 1992. The VW 2.5 liter 5 cylinder engine that was débuted in 2005. The Audi 4.2 V8 changed to a chain configuration in 2004. The VW & Audi 2.0 T gasoline engine began life as a belt motor in 2005.5 and then went to a chain drive in 2008 in a few models, then the rest of the fleet in 2009.

Gear case (2)Karmakanix Service Information on Timing Chain Engines

Gear case (2)Karmakanix Knowledgebase Information on Cam Chains and Timing Chains

Gear case (3)