15 Jun 2024
The voice of the independent garage sector

Can you feel the tension?

Schaeffler’s REPXPERT team has spent the last few months making sure technicians keep the front-end auxiliary drive (FEAD) system at the forefront of their minds.
    
We spoke to Schaeffler REPXPERT Alistair Mason, who explained why taking the time to assess this critical system is so important: “If the FEAD system or belt should fail, that’s bad in itself, but it could potentially cause a lot more damage. The risk is that if the belt gets behind the pulley it can actually get drawn into the timing belt system. If that then affects or derails the timing belt, then it can cause catastrophic engine damage.
  
“A lot of vehicle manufacturers are now putting a service schedule on the auxiliary drive belt on the front of the engine, either for time or mileage, whichever comes first. The trouble is that every manufacturer is different.
    
“A timing belt replacement is quite a common job. In many cases, part of that procedure is that you have to remove the auxiliary drive belt. What we always advise is that you replace both belts at the same time. You’ve got to take it off, it’s part of the job, and you have to put it back on, again because it’s part of the job. So why not put a fresh one on? There’s no real additional labour involved.”

Preventative maintenance
Through the INA brand, the entire FEAD kit is available, as Alistair noted: “We supply not only just the belt, but we supply the whole system including all ancillaries.”
    
Changing demands and cross-system dependence on increasingly strained areas means that this has become the lynchpin of a whole host of related functions, all of which means that the car’s owner really doesn’t want a major failure here. Alistair went on to provide some context: “Look at the complexity of the system now; In the old days, when you have predominantly what they called a fan belt, you only had to worry about an alternator and maybe a water pump. Then they added more components to the system, so they would put another longer belt on, then they might decide to add a power steering pump. It’s driving a lot more now, so there’s a lot more wear on the belt than there used to be because everything is working that bit harder.”

Regular basis
With the REPXPERTs in garages every day providing advice on best practice as well as much-needed training, we wondered where the issue was being felt: “It’s a problem that we see on a regular basis through our warranty department as well, which is probably where we’re seeing it most. We also get a lot of calls about it.
  
“What can happen is that something else on the system could have a fault, whether it be a tensioner or a pulley or an idler. Maybe it is derailing the belt a little or it’s not got the right tension. Perhaps it’s not taking the pulses out of that belt, which will then cause other components to fail, which, of course, will then keep getting sent back under warranty, which, actually, you’ve still not diagnosed.”
    
So where is it then? “The most common root cause of problem on the FEAD system is on the alternator, which has what we call an overrunning alternator pulley (OAP). “When an engine is running, the crankshaft pulses as it goes around, and those pulses are transmitted through the back of the engine. In the transmission, we can absorb those pulses with a dual mass flywheel, to which the clutch is bolted. On the front end we have a similar system. What happens then is that the belt drives the alternator, which is going about four times the speed of the engine. As the engine is on a firing pulse the belt gets faster, so the alternator gets a little bit faster and then it comes round onto compression, so the engine slows down a little.
  
 “You effectively now have a solid pulley, but if those pulses are not being absorbed, the belt starts to thin, and then the tensioner tries to hold the tension on the belt and wears out. The car then goes into a garage, where it is found that the tensioner is broken. So the mechanic puts a new tensioner on and the car goes out and it’s okay for a couple of weeks, but then it snaps again.”
    
On the solution that Schaeffler offers, Alistair observed: “This is why we recommend a complete set rather than single components. The alternator has become a starter generator. Not only is it being driven, but it’s now actually a driver as well. When you want to start the car, we can actually start it on the alternator. Then we start going down the road, it will turn into a generator. Then you might floor the car, so you want e-boost, and now it drives the engine again.
    
“As a result, we’ve now got a stronger belt on there, with a slack span on the belt. The tight span is where it’s all being driven. The slack span is where your tensioner goes in to hold the tension. We have to have a tensioner that can accommodate that, so we basically have a little dual mass flywheel, which is a common repair on the three-cylinder BMW/Mini engine. The best practice to protect your customer is to replace the belt. While that belt is being replaced, check all the other tensioners, pulleys, and idlers on the system just to make sure there’s no wear. If there is, they’re easily replaced. It’s a cost saving in the long run to the customer because you’re already working in that area.”
    
Alistair added: “By not replacing it, you’re not looking after your customer, doing them a favour. Not spending £20 on replacing the belt could turn into a £2,000 repair bill.”

Essential
When a garage has a car in for a FEAD system replacement, you need the right parts. Explaining why they should opt for INA’s offering, INA Product Specialist Brad Adams said: “Other than via the main dealer, only by opting for an INA FEAD KIT are you getting a complete and genuine OE quality kit. That’s obviously essential because the mechanic wants to fit the same as what he’s removed from the vehicle.”
    
With everything increasingly interconnected, a problem with one part of the system can have a major effect on another, as Brad explained: “With the timing belt system, it’s one of the riskiest jobs on the vehicle. If you have a failure on the FEAD, that in turn can knock off the timing belt and cause catastrophic damage to the engine. This means it really is essential to use genuine original equipment quality parts.”
    
One of the long-term messages from Schaeffler, apart from making sure to follow best practice procedures, is to always use genuine quality replacements. Explaining this long-standing ethos, Brad said: “Vehicle manufacturers spend between two and ten years on research and development, from the conception of designing an engine to when the vehicle actually rolls off the production line. Schaeffler is working with them from day one to provide the parts and systems they need for original installation, and these same parts are then sold to the aftermarket in our INA boxes – everything comes off the same production line.”
    
Coming back to the FEAD system specifically, as Alistair explained, the changing make-up of vehicles has added to the extra stresses: “Moving from a 12-volt system to a 48-volt hybrid system can create up to 200% more load on the belt, so you can see why VMs are adding service intervals for the system. 48-volt hybrids often have a starter generator. A lot of vehicles will be gathering charge under braking, and that charge will be stored in the batteries. When the engine needs extra power, the starter generator will kick in. The crankshaft that’s turning the front-end auxiliary drive will be going in a clockwise direction, with the right-hand side of the belt being pulled by the crankshaft. We call that the ‘tight’ span. At the same time, the left-hand side of the belt is effectively being pushed by the crankshaft. We call this the ‘slack’ span, which is where the tensioner is located. When the starter generator kicks in to deliver that power, it actually swaps the sides of the tight span and the slack span because that begins to drive the belt.”
    
Brad added: “We also have newer FEAD technology products available, such as the Omega Tensioner, so-named as it is the shape of the Greek letter, which is able to actively ‘roll’ across the belt, adding tension to whichever side of the belt it is needed.”
    
For more information, visit: www.repxpert.co.uk