Tickford Racing boss Tim Edwards has raised rubber debris as an engine reliability risk at the Bathurst 1000 after a failure for the James Courtney Ford Mustang in Practice 3.

Co-driver Zak Best was behind the wheel when an alarm appeared on the dash of Car #5 and would ultimately come to a halt on the side of Conrod Straight, triggering the only red flag of the hour-long session.

When the teal machine was returned to the pits, it was revealed that a belt underneath the bonnet had been, to use Edwards’ words, “shredded”.

He cited marbles, which are larger this year due to the switch to the soft compound tyre at Mount Panorama, as the probable cause.

“It was the same issue we had on Thomas’s [Randle] car at Sandown, actually,” noted the Campbellfield squad’s Team Principal.

“The front belt off the engine just shredded itself. We think the cause is picking up debris.

“You get a ball of rubber or something goes in there and obviously the whole front of the engine’s exposed and it just gets caught between the pulley and then snaps the belt.

“We’ll learn from it, we’re already talking about, ‘Okay, if it happens in the race on Sunday, you’ve just got to roll down the hill,’ because you lose the water pump as well, so everything was getting hot.

“So, the first time’s obviously the driver saying, ‘I’ve got no power steering.’ The next thing is everything going all red on the screen there with all the temperatures going through the roof.

“It’s a concern, though.”

Consistent with Edwards’ theory, it has been noted that the harmonic balancer on the Ford engine is rather exposed.

Edwards pointed out that the lower-downforce Gen3 aerodynamic package, which does not feature a splitter like the Gen2 cars of old, is likely contributing to the problem.

“We’re putting fresh belts on all the time but, unfortunately, it doesn’t matter whether the belt’s done one kay or a thousand kays,” he lamented.

“If you just get that rogue bit of rubber, it just bounces up through… We don’t have the diffuser under the bottom of the car, so it’s a lot more exposed and potentially prone to debris coming in.

“Anyway, we’re just going to work through it and try and work out a plan.

“You can’t drive around all Sunday sort of avoiding the balls of rubber so it’s going to be a challenge for everybody.”