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FCP Euro Service Kits

FCP Euro Kits

Automotive engines are a myriad of rubber hoses, vacuum elbows, belts, and bushings. As they wear out, some may fail more catastrophically than others. I've had Volvos with perforated cooling hoses, missing serpentine belts, and rotten engine mounts come through my garage. But not many people have driven a car with a broken timing belt - proving the severity of these belts differs greatly.

The Serpentine Belt

 

v70-xc-99-serpentine-belt Volvo 5-Cylinder Serpentine System

 

Automobiles use a growing number of hydraulic and electrical systems to provide us all of the creature comforts we know and love. Power steering, air conditioning, and even basic electrical systems couldn't have been possible without the serpentine belt.

Serpentine belts piggyback off of the engine's crankshaft rotation to spin various accessories, sometimes called an accessory drive. The Volvo engine pictured here utilizes a power steering pump on the top, an alternator in the middle, and A/C compressor on the bottom, with a tensioner pulley to keep the belt taut and from slipping. When the large crankshaft pulley spins, everything else spins with it, activating each respective system.

If this belt were to break while driving, I'm not trying to say it wouldn't be a major inconvenience, but you may be able to limp the vehicle to a safe place before you're dead in the water. Don't run an an engine with a broken serpentine belt for any longer than necessary - some engines have serpentine-driven water pumps, and an overheat condition would be imminent if the belt breaks. Luckily, serpentine belts are easy to check and cheap to replace.

 

Worn Belt Worn Serpentine Belt

 

The Timing Belt

What makes a 5-cylinder engine sound so sweet? Which bear is best? How long does a timing belt last? These are questions only a mere fraction of humans know the answer to, except for one. A timing belt lasts until the day your engine stops running in a flurry of magnificent metal-on-metal noise. (Most cars)

The timing belt is the most important belt under the hood of your car, and here's why. Like the serpentine belt, the timing belt gets its rotation from the crankshaft's motion. But rather than driving trivial systems like A/C and power steering, the timing belt spins mission-critical components in perfect time, and can't miss a beat.

Timing belts ride on the crankshaft and rotate the camshaft pulleys. These camshaft pulleys are what control the engine's valves to supply or exhaust the combustion chamber of its air/fuel mixture.

Internal Combustion

In the above graphic, the camshafts, valves, spark plug, piston, connecting rod, and crankshaft are all visible for a single cylinder. In this application, the timing belt is responsible for rotating the two camshafts at the top of the cylinder head. If these suddenly stop spinning on a running engine, it's possible for a valve to remain open when the piston reaches the top of its stroke on one or more cylinders. Severe mechanical damage will occur at this point, destroying valves, pistons, and sometimes entire cylinder heads.

Redblock TortoiseMost overhead cam engines like this are of the "interference" nature, however there are a minority of engines unaffected by timing belt breakage. These are called "non-interference" engines. My girlfriend's mother drives a '92 Volvo 740 powered by the "Aging Tortoise of The Automotive World" redblock engine, and can run her timing belt until it snaps. Nothing will happen, except for a stalled engine and an inconvenient tow home.

Don't wait for the inevitable

When in doubt, assume your engine is of the interference type, and change the timing belt at manufacturer recommend intervals. In harsher climates or extreme usage scenarios like racing, check all belts frequently for cracking, separation, or dryrot to avoid premature failures.

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Written by :
Alex Fiehl


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