Three vehicle repairs you should avoid attempting yourself
Repair shops of every stripe see it almost every week: vehicles dragged in with some type of problem their owners tried to tackle by themselves.
With repair and maintenance costs of even the most basic vehicle climbing, many drivers are tempted to take care of some routine repairs themselves. But unless you know what’s behind the technology involved, your DIY efforts can earn you a larger-than-expected garage invoice. Here are some of the top repairs best left to the professionals.
Axle servicing. You notice a few drips of oil coming out of your truck’s or SUV’s axle near the point where the driveshafts attach. The most common cause is a failed pinion seal, a relatively inexpensive part on most vehicles.
What’s the harm in crawling underneath to tackle this job? Well, when reinstalling the nut after replacing the seal, the most common error is to over-tighten it. Inside that axle is a specially designed crush sleeve that is designed to hold the pinion gear in place with accuracy measured in thousandths of an inch. Over-tightening the nut will collapse this sleeve, causing a misalignment of the gears, which leads to premature wear.
While a pinion seal can cost less than $30 on average, a new gear set can easily run over $1,000 before labour and taxes. Ouch!
Brake replacement. Many of us have seen mechanics complete this common task before, replacing the brake pads and rotors. After all, only a few bolts have to be removed once the wheel is off, and taking off the rotors and pads — after the caliper is removed — can be done by hand on many vehicles.
There are some who argue that working on any safety system on any vehicle without a technician’s licence should be outlawed, and many municipalities have bylaws prohibiting working on vehicles on residential property. But people tackle all types of tasks, such as home electrical and HVAC repair, without worrying about the rules.
If a vehicle is equipped with anti-lock brakes, there is a high amount of reserve pressure in the hydraulic system that’s maintained at all times on most vehicles in case of an emergency.
Open any part of this system before releasing that pressure and you can be in for a nasty surprise gush of brake fluid coming out at high pressure. Techs will pump the brake pedal a few dozen times with the ignition key off to relieve this pressure before tackling most brake work.
Another common mistake is letting the brake calipers (the wheel units that actually do the work of applying the pads) hang by their flexible hydraulic hoses while completing other work.
These hoses were never designed to hold the weight of a caliper. And if they’re old, they can snap or leak or twist to the point where brake-fluid flow is restricted.
Spark plug replacement. What could possibly go wrong with something as simple as replacing your spark plugs? Lots, especially if you don’t use the right tool and don’t apply the correct force.
While many types of socket heads will fit over a spark plug and securely grab its tooled edges, a proper spark plug socket has an inner liner designed to protect its fragile ceramic shell.
And even if you use this tool, if it’s not properly aligned on the plug or if the initial force used to unlock the thread isn’t sharp enough, it’s easy to break the plug or round its edges, especially on older and high-mileage engines.