We've had a 2013 Subaru Forester 2.5X for a little over two months. When I put my foot on the brake pedal, it feels spongy and then slowly continues to sink almost to the floor. When brakes do this on other cars, its because the master cylinder is leaking. This sponginess resulted in my foot slipping off the pedal and the Forester bouncing over a 7-inch curb and hitting the wall of a restaurant.
With the RPM as high as the factory set them, once the brake is no longer applied the car juts forward at about five miles per hour. This did $13,000 in damage to the restaurant's outside wall and $3,500 to the Forester. I don't think these brakes are safe. I also think that the engine RPM should be able to be reduced, so that the car barely moves forward when the brakes are released -- like other cars. Is there something wrong with the Forester? Is there anything I can do to remedy its problems? -- Gary
Cars are designed to move forward in drive when you take your foot off the brake -- it's a safety feature to keep your car from rolling backwards, says our expert mechanic.
"For most manufacturers, the engine RPM (revolutions per minute) at idle will be set around 500," says Mubasher Faruki, automotive instructor with BCIT. "That's because if you're sitting on a flat surface the car is designed to roll forward, to give you that creep effect – it could probably could reach speeds of 2-3 miles per hour."
Most modern vehicles combine this with a second safety feature: you can't shift into drive without your foot on the brake.
In your case, Faruki says it's impossible to tell whether your Forester's behaviour is normal without examining it.
"The first thing you'd have to do to is see if the vehicle has a problem," Faruki says. "We'd have to verify the complaint that the idle of the vehicle is too high and see whether the brakes are operating normally," he says.
Subaru says they've had no reports of problems like yours.
"We are unaware of any underlying issue and do not have specific recommendations or remedies," says an email from Subaru spokesman Joe Felstein. "Subaru has not had any reported issues or comments regarding our brakes and engine RPMs in the past."
Faruki says the brakes' behaviour could even be normal depending on the circumstances. If you're pressing on vacuum-assisted brakes when the vehicle's already stopped (like when it's parked or you've just shifted into drive), it's normal to be able to push the pedal all the way to the floor.
"If you did that while you're moving, you'd lock the wheels up because you're supplying so much pressure," Faruki says. "But if you're just sitting there, power-assist will let you push the brakes to the floor, but it's not doing anything."
Still, if you perceive a problem with your brakes, call a mechanic, or the dealer, if the car is under warranty. Any mechanic or dealer should take complaints of brake problems seriously, Faruki says.
"Phone up the dealer – I don't know of any dealer who wouldn't send someone," he says. "I'd hope that a customer would get any possible safety issue looked at before an accident were to happen."
Spongy brakes should be taken seriously because they could be a symptom of brake trouble, such as a leaky master cylinder or air in the lines. But you won't know whether your Subaru has a problem, or whether you just need to get used to its brakes, until you get it checked.
"The the number one thing they train us technicians to do is to verify that the vehicle is doing what the customer says," Faruki says.
As for RPM, Faruki says most vehicles don't give mechanics the option of adjusting the factory settings.
"Generally speaking, there are no systems built in that let a technician adjust the engine idle settings," he says. "It's still possible to do, but they're set that way for a reason."
Please send your automotive maintenance and repair questions to firstname.lastname@example.org