Top 10 Worst Things Your Mechanic Can Tell You

There are lots of things you do want to hear from your mechanic:

  • "It was nothing. A wire fell off. I reattached it. No charge."
  • "The gas cap was loose. That's why the Check Engine light was on. It'll go off by itself."
  • "Oh, sure, we can clean dog puke out of the heating vents. We do that all the time."

But there are some things you never want to hear, over the phone, from your mechanic. Here's our Top 10:

1. Seized Engine Due to Lack of Oil

"The reason your engine stopped running is that it's now a melted mass of amalgamated metals. What used to be aluminum pistons, steel cylinder walls and an iron crankshaft is now a 900-pound garden sculpture. The Smithsonian wants to put it on display."

Cost: $3,000 for a used engine, up to $10,000 for a remanufactured engine.

The lowdown: A "seized" engine means that your lubrication failed (that is, you had insufficient oil or oil pressure), and the expensive moving parts of your engine scraped each other into a heated glob of useless scrap metal. Unfortunately, there's no way to fix a seized engine. Instead, the engine needs to be replaced with a used or remanufactured engine. What happens to your old engine? A recycler will finish the melting job, and the engine will be transformed into thousands of tiny Bic lighters.

2. Hydrolocked Engine

"That 4-foot-deep puddle that you tried to cross? You sucked some of it into your engine's cylinders."

Cost: $3,000 to $10,000

The lowdown: There are certain places water shouldn't be — like inside your iPhone, on your original Matisse watercolor or inside your engine's cylinders. Normally, your engine's cylinder contains air and droplets of fuel. The air is compressible, so when the piston squeezes everything, the pressure just goes up. Water is not compressible, so when the piston tries to squeeze the water, the piston loses. Then all the expensive parts that are attached to the piston get bent or broken. Just like your bank account.

3. Overheated Engine

"When you saw the paint on your hood was starting to blister, did that give you any kind of hint that you might have been overheating?"

Cost: $100 to $10,000

The lowdown: If you catch an engine overheating early enough and take action, you can get by cheaply. It could be a leaky hose, a stuck thermostat or a loose clamp.  If your car overheats badly, or frequently, you can do serious damage. The most common results of frequent or severe overheating are a blown head gasket, a cracked head or a cracked block. Those are, respectively, expensive, really expensive, and you may wind up saying, "I guess I won't be retiring for another year."

4. Transmission STB (Soiled the Bed)

"Did you notice when you put your car in Drive, it doesn't move? We figured out why."

Cost: $300 to $5,000

The lowdown: The good news is that your engine is still running. The bad news? It's no longer connected to the wheels. Transmissions can fail for a number of reasons. These days, it's not uncommon for electronically controlled automatic transmissions to have problems related to software or solenoids. Those are not disasters and can be fixed for relatively little money. When the transmission's internal components start to disintegrate (like when your mechanic removes the transmission drain plug and chunks of metal fall out) due to old age, overheating the transmission or animalistic driving tendencies, it's time to tap the home-equity line of credit.

5. Cracked Head, Blown Head Gasket or Cracked Block

"That stuff blowing out of your tailpipe isn't just water. It's antifreeze."

Cost: $1,000 to $4,000

The lowdown: There are a few places you should never see antifreeze: falling from the sky, in your cereal bowl or coming out your tailpipe. The engine's cooling system is a closed system, meaning that the coolant circulates from the engine's cooling passages to the radiator, the heater core and back again. It should never leave that loop. If it's somehow getting into the oil passages or the cylinders (and, from there, out the tailpipe) something has gone terribly wrong. Your head gasket has cracked, your head itself has cracked or, worst of all, your block has cracked. These problems are often the result of overheating (see No. 3).

6. Broken Timing Belt

"Look in your glove box. If you open the shrink-wrapped booklet that says Owner's Manual, you'll see you should have changed your timing belt 20,000 miles ago."

Cost: $1,500 to $3,500

The lowdown: There are two kinds of engines: interference engines and non-interference engines. Or, as we refer to the interference engines in the trade, motor wreckers.

An interference engine is actually a more modern engine design, where the valves open wider and into the path of the upcoming piston. This lets the engine breathe better, giving it more power and better fuel efficiency. It all works fine as long as your timing works fine — when the valves are open, the piston is down, and when the piston comes up, the valves are closed and out of the way. If your timing belt breaks or jumps a notch on an interference engine, the piston smashes the valves, and you need a valve job ... at least. That's why it's crucial to change the timing belt at the recommended interval, before it gets anywhere near the point of breaking.

On a non-interference engine, a broken timing belt will leave you stranded, but it won't crush your valves. You can ignore the timing belt change on one of those engines if you don't mind getting stuck. On an interference engine, you're rolling the dice on a large boat payment for your mechanic.

7. Transmission Fluid in the Brake Fluid Reservoir

"That was the brake fluid reservoir, to which you added transmission fluid."

Cost: $800 to $2,000

The lowdown: If you catch this mistake before you actually get back in the car and step on the brakes, and have the car towed to your mechanic, you may get by with just a new master cylinder. But once a petroleum-based product, like transmission fluid or motor oil, is pushed through the brake system, pretty much everything has to be replaced. The oils attack rubber seals, and everything except the metal brake lines has rubber seals. Once you've used the brakes and sent this stuff through the brake lines, grab your credit card and check your credit limit!

8. Fried Computer

"You hooked up the jumper cables backward."

Cost: $1,500 to $100,000, in the event plastic surgery is required.

The lowdown: In lots of cars, there's some type of protective circuitry in the event that you accidently reverse polarity when hooking up jumper cables. However, that's by no means true for all cars. If your car is one of the unlucky ones, you might be looking at having to buy a new computer for your car, and maybe a few new wiring harnesses, too. Even worse, you may incur so many confounding electrical problems that the best thing you could hope for is ... fire. Even if your car is OK, you might blow up one of the batteries in the two cars. If that happens, you might need to buy yourself a new face, too. (Maybe you can buy my brother's face — we've been trying to get rid of it for years.)

9. Worn Clutch

"That smell that's been following you around for miles? It's your clutch burning up."

Cost: $1,000 to $2,500

The lowdown: The operation of the clutch is based on friction. It's a tricky business to apply that friction slowly enough so that A) your engine doesn't stall and B) your passengers don't get whiplash. At the same time, you have to apply the friction quickly enough so you don't "sand down" the clutch and end up with no friction material left. When you continually let out the clutch too slowly, while giving the engine lots of gas, you're essentially wearing out the friction part of the clutch. Like a piece of sandpaper, a smooth clutch with no grabby surface can't do its job. If you're doing a bang-up job of it, you can actually start to smell the clutch burning as you wear it down. How quickly can you do this? We actually have a friend who did exactly this and destroyed a clutch in as little as 20 miles. No kidding! You know that $1,200 you saved by buying a manual transmission instead of an automatic? You're about to spend it on your first clutch replacement.

10. Catastrophe at the Repair Shop

"Your car fell off the lift, and your boyfriend and I are going camping this weekend."

Cost: $0 if your mechanic has insurance; $25,000 if not.

The lowdown: You know how you'll occasionally break a glass at home or drop a fork down the garbage disposal? Well, these kinds of little accidents happen. In the repair business, a tiny moment of carelessness can lead to something much more exciting, such as a car falling off the lift or catching fire. These are exciting moments for mechanics. And once they're over — and everyone is present, accounted for and still fully limbed — we feel a moment of euphoria to still be alive.

Unfortunately, that's usually the moment we choose to call the customer and share this good news. "Good news! You're car fell off the lift, but nobody was underneath it!" For some reason, this isn't always received as good news. Fortunately, reputable repair shops have Bonehead Insurance for such calamities. You may be able to go out and buy that new Accord you've had your eye on. Remember: It's only a car. Cars can be replaced. People can't. At least that's what we keep telling our customers.

© Cars.com 05/1/2013