This writer took his first auto maintenance course at sixteen. Going for his car license he wanted to be able to fix the vehicle if anything went wrong; take it apart and reassemble it, if necessary. What struck him during the course was how simple it all really was. A lesson remembered to this day was if the fan belt broke, simply take some panty hose, run them along the pulleys for the crank, then the fan, the alternator, the tensioner and the water pump, and drive off to the next service centre to buy a replacement.
Much has changed since those innocent times. First off, not so many women wear pantyhose these days. Most important though, pantyhose will not get you to the service centre. Today’s engines are much more complex than they were even 20 years ago. The clearances are smaller and everything of the engine is in a tighter, more compact space. There is no way even the most savvy and skilled driver will be able to get a pair of panty hose anywhere near the necessary tensioners and pulleys.
The biggest change perhaps is that the belts last longer and are made from a different compound than they were back then.
Welcome to the world of EPDM rubber and tougher belts
“The old belts were made from Neoprene which would degrade after a while,” said Marc Therrien, account executive with Veyance Technologies Canada Inc., the exclusive manufacturer of Goodyear Engineered Products. Neoprene is DuPont’s trade name for polychloroprene. This is a family of synthetic rubber that is known for good chemical stability and its ability to maintain flexibility over a wide temperature range. Invented by DuPont in the 1930s, this substance quickly became the standard material for underhood rubber in cars, trucks and all manner of vehicles. Checking these belts for wear was a regular activity for all automotive technicians and fairly straightforward.
“The technician would simply look for cracks and signs of wear, and replace the belt,” said Therrien.
The belts were fairly inexpensive and fairly standardised across many lines of vehicles. Today’s belts are made from EPDM (ethylene propylene diene M-class rubber) – a more advanced form of synthetic rubber.
“These new belts are like car tires – they do not crack or show signs of wear that the old belts used to have. They also wear like car tires so they might look fine but in fact they are worn and ready to fail,” said Rick Adams, product manager at ACDelco. “Belts are lasting much longer due to the new materials,” he adds.
“Serpentine belts need to be diagnosed differently from what they used to be,” said Bill Hay, vice-president of sales at Dayco Canada Corp. “Belts used to be manufactured from a neoprene compound which was easy to spot when it was about to break, it would become cracked and also the bottom side of the belt would start to chunk out and fall apart.”
Echoing the statement of Adams, Hay stressed, “technicians need to realize these belts wear like car tires. We have a wear gage that measures the wear of these belts.” The wear gauge is a universal instrument that can be used on any belt and is given away free by Dayco.
In fact, these wear gauges are freely available from most belt manufacturers so there is no excuse for any technician to be without one. The tool is simple.
“It’s like dropping a coin in a tire tread to check for wear in days gone past,” said Adams.
Since cars have so many accessories that are belt driven, a worn belt can cause problems such as poor charging, reduced air conditioner performance and increased pulley wear, amongst others. According to the Car Care Council, one-out-of-five vehicles on the road need a new belt.
“Tensioners are another critical component that needs to be inspected on a regular basis,” said Randy Chupka, marketing manager, automotive replacement market for Gates Canada. “A tensioner is a relatively inexpensive part to replace and can help protect other components such as the water pump, alternator and A/C compressor from undue stress and premature failure. An essential best practice for a technician considering belt replacement or any other component within the accessory belt drive system is a diagnostic check of the tensioner. While the engine is running, with the air conditioning on, check the tensioner arm for excessive vibration. If the tensioner arm vibration can be seen with the naked eye, a new tensioner is needed. With the engine off, also inspect the pulley surface and spin the pulley to check the bearing. Any unusual wear is a sign that replacement is needed.”
Gates’ Stretch-Fit belt is a new technology that does away with the tensioner and is “designed by the OE to only work on drives without a tensioner,” said Chupka. “What you may have is that the water pump drive for instance may use a Stretch-Fit belt and has no tensioner. Meanwhile the A/C drive on the same vehicle may have a drive that has a tensioner and therefore you can use a standard serpentine belt for the A/C drive. These Stretch-Fit belts are very application specific and can only be used for the drive they were designed for.”
Timing belts are often neglected to the detriment of the vehicle and the owner.
“If a serpentine belt breaks, what happens is that the alternator goes and the car stops at the side of the road. You put on another belt and you go on your way,” said David Hirschhorn, director of branding for CRP Industries Inc. “When a timing belt breaks what happens is that a piston might come in contact with a valve and when that happens the cylinder head has to come off the car. It will go from a repair job that cost a few hundred to something that might be more than the value of the car.”
Many water pumps are now run off the timing belt and not the serpentine belt. CRP offers the Pro Series that includes a water pump, tensioner, timing belts and idlers in one package.
“What we are finding is that a lot of technicians, when they are going in to do the timing belt – it usually takes two to three hour to do the job so when you go in to do that job you might as well change everything,” said Hirschhorn. “The cost of a water pump is 20 to 30 bucks. With all that labour involved you might as well change everything when are you are there. The technician should know according to the service advice of the particular vehicle when you should change the timing belt. If the car is not used much it should be changed every three to four years.”
And now the hoses
Like the belts, hoses have been forced to change because of the complexities of the engine.
“The biggest change in the industry is the use of more branched houses and much higher operating temperature in the engine bays because the engines are running much harder,” said Abe Garweg, vice-president of product development at CRP Industries Inc. “Higher temperatures mean higher operating pressures. The other thing is that aluminium radiates heat much more than cast iron. On top of everything else, cars are more aerodynamic. They have belly pans, radiator openings are smaller and the engine bays are smaller. So the underhood temperatures are much higher. Obviously these increased operating temperatures affect the belts and hoses – everything under the hood that is made of rubber. That is why new compounds are necessary.”
Unlike a simple hose, branched hoses might have many outlets or inlets and be specific to that engine and vehicle with certain options.
“They are very complicated hoses. One end goes to the heater valve, one goes to the water pump one goes to the radiator,” said Garweg. “Some look like modern sculptures. The modern hoses are more expensive but t
hey also last longer. Technicians should be aware of these branches and inspect them.” Garweg recommends replacing the radiator hose every five to six years. “If you live in Arizona or Florida you should replace more frequently than if you live in Massachusetts.”