Under the Hood: Time for a timing belt change

McClatchy-Tribune Information Services

April 8, 2019

Q: I have a 2004 Subaru WRX STi with 50,000 miles. I haven’t changed the timing belt on it – Subaru recommends changing it at 105,000. Am I living on borrowed time?

—Kevin H.

A: Kevin, I’d get on this right away! Your WRX STi engine is of interference design, meaning the valves will hit the pistons should the timing belt fail. Subaru recommends replacement of the belt at 105,000 miles or 105 months, which you are significantly past.

There are a variety of factors that affect timing belt life. Miles driven, additional friction/flexing due to frequent engine start/stops, temperature extremes, humidity, degradation due to oil or coolant seepage/leakage, and exposure to airborne contaminants will take their toll.

My take on this is the risk of continuing to drive is unacceptable, as a belt failure could result in a $3,000 or higher repair bill, and the 105/105 recommendation is at the higher end of typical manufacturer belt replacement intervals. Removing covers to perform a visual inspection of the belt is an option, but the labor to do can be significant, and the limited inspection view won’t provide conclusive information.

When a timing belt is replaced, it’s a best practice to also proactively replace the water pump (often driven by the timing belt), idler pulleys and perhaps the belt tensioner. This can almost double the cost of service compared to a simple “belt slap,” but it is justified due to the relationship these parts have with the belt and the labor to get to them if need be in the future. Your WRX is an amazing car and it deserves the best of care!

Q: I recently clobbered a big pothole, which destroyed my left front tire. The tire guy said the rim had a minor dent but the new tire holds air fine and it “spun smoothly” when he balanced it. To play it safe this was installed on the right rear of the car. After driving now for a while I’m noticing the steering wheel is not quite straight. Is this a problem? The car drives straight and smooth.

—Abby

A: Ouch! This is unfortunately becoming a more and more common situation! Your crooked steering wheel indicates the pothole strike has affected wheel alignment, particularly the toe (parallel tracking) of the front wheels. If left unchecked you will likely see rapid tire wear on one or both front tires, more so on the edge of the tread.

A careful inspection of the front and rear suspension and left rear tire/wheel is needed! It’s likely that a suspension component or chassis attachment point has been bent slightly. When wheel alignment is checked the technician will be concentrating on camber (inward or outward tilt of the wheels/tires as viewed from front or rear) and caster (angle of the steering axis, similar to the fork angle of a bicycle), in addition to toe. If all components appear undamaged and camber and caster are OK, a simple toe adjustment may suffice, restoring steering wheel position and ensuring tire life. If left/front camber and/or caster are incorrect or there are any signs of damage, I’d begin an insurance claim and seek to have applicable left front suspension parts, particularly the ball joint, replaced, along with the damaged wheel.