Repair And Fix it

Like most ponderings in automotive repair, the question of removing spark plug wires from a running engine isnt necessarily so much one of "could" as it is of "should." Technically, yes, you can yank the plug wires off of a running engine just as easily as you could one that isnt running, but it may not necessarily prove conducive to you or your cars good health.

You Could

Removing a plug wire from a running engine isnt likely to result in catastrophic engine failure, particularly if you put it back on shortly afterward. All spark plugs misfire from time to time, you just dont notice it because its intermittent, random and usually happens so quickly that the cylinders firing again before the engine has a chance to vibrate. So, intentionally creating a misfire by removing the plug wire for a few seconds or even a few minutes isnt likely to destroy anything on most engines.

Common Effects on the Engine

Most engines have a rubber ring on the front of the crankshaft called a harmonic balancer; on the outer edge of the balancer is a heavy, metal ring. When the explosions in the engines cylinders push down on the pistons, the forces they exert quickly accelerate the crankshaft. When that accelerations over, the crank tries to slow down, resulting in a constant cycle of acceleration and deceleration that manifests as vibration in the crankshaft. The metal ring on the balancer resists these sudden, but tiny, vibrations and keep the crank from tearing itself in two. Over a long enough period of time, a dead cylinder and the resultant heavy vibration will over-work the balancer, causing it to fail. Once that happens, you could be looking at serious damage to the engine.

Effects on the Converter

Your cars catalytic converter works something like a blast furnace to convert toxic gases produced by your engine into more inert forms that wont drown polar bears or grow fish with three eyes. The converter takes advantage of unburned fuel -- which is, itself, a pollutant -- coming from your engine and uses it to fuel the furnace in the converter matrix. More fuel means more heat. Killing the spark in one cylinder will drastically increase the amount of fuel pouring into your exhaust, which will, at some point, cause the converter to overheat and fail. The engines control computer will compensate for this to some extent, but you can count on extra fuel going into the exhaust.

Lean-Out

Depending upon the computers control strategy, disconnecting a plug wire and leaving it that way could seriously fry something. When the oxygen sensor detects excess fuel in the exhaust, your cars computer may assume that this represents a net excess of fuel through all the cylinders. It will respond by decreasing the amount of fuel injected to all of the other cylinders in order to get the air/fuel ratio back in line. The resulting lean condition will increase combustion chamber temperature, causing overheating, detonation in the engine and, eventually, complete meltdown. Most computers do have programming provisions to account for a dead cylinder, and wont react this way; but some dont, and theres no way to be sure unless you know exactly how your fuel injection system thinks.

Safety Issues

Before pulling the plug wire off of a running engine, bear in mind that your are, in fact, grabbing a live wire with about 40,000 volts worth of electricity coursing through it. Normally, this electricity will pass through the plug wire and race to the spark plug, which acts as a ground. But when you remove that ground, the spark is going to find the next, most convenient ground. If you happen to be touching the body of the car when you pull the wire off, then you become that ground. While electricity normally wouldnt arc through the insulation, even if it is a bit old and damaged, removing the primary ground will make that spark pretty determined to get out whatever way it can. Its not likely to kill you unless you have heart or nervous system problems, since the amperage is very low -- but the sensation is rather, shall we say, "life affirming."

A good diagnostician is something of a Car Whisperer, one who can pick up on the tiniest of clues to intuit both the cause of a problem and the avenue to its solution. Tire cupping isnt the most common wear pattern out there, but it is one of the most serious and telling in terms of diagnosing the chassis condition.

Cupping

In terms of tire wear patterns, "cupping" ers to a series of regular dips appearing in the outer edge of a tires tread. Also called "scalloping," these dips look as though someones taken shallow scoops out of the rubber with the worlds most sinister ice cream scooper. This sort of cupping shouldnt be confused with the cupping that often occurs on large drag tires. In this context, cupping happens when the tires inflation pressure is too low and the center of the tire curves upward or "cups" at high speed.

Cupping Causes

Cupping is a sign of rapid tire bounce or side-to-side oscillation. Theres no one single cause behind such bouncing or oscillations; any component that connects the wheel to the car is suspect. Worn shock absorbers will fail to control wheel movement, allowing the tires to bounce and cup the tread. Suspension bushings and ball joints are secondary suspects, followed by wheel bearings and steering end-links. The last two, however, should exhibit noticeable symptoms -- vibration through the steering wheel and chassis -- well before cupping becomes an issue.

Argument 1 -- Driving on Cupped Tires

Some contend that cupping isnt necessarily a death sentence for tires, provided that the lowest point in the scallops dont extend past the tires lowest safe wear zone. After youve fixed whats causing the cupping, the high points in the scallops will wear far more quickly than the low points, which should smooth them out over time. Rotating the tires may help to speed the smoothing, since doing so will at least change the frequency of oscillation acting upon that tire.

Argument 2 -- Not Driving on Cupped Tires

While it is true that fixing the problem and driving on cupped tires may eventually smooth them out, the fact is that the low points in the scallops will continue to wear just like the high points. Granted, theyll wear more slowly, but even with the best-case scenario, youre looking at a tire with a serious -- if smooth -- bald strip around the edge. From this perspective, any cupping at all is the death knell for your tire and a sign that it needs replacement ASAP.

Conclusion

Provided that youve replaced the worn shocks, bushings or relevant suspension component, driving on a cupped tire will eventually smooth it out to some extent. But thats like saying that sooner or later the wind will eventually erode mountains. True, it will, but itll also erode the valleys between the mountains and create low-lying dips in the landscape. Its a game of time and specific conditions, and one youre probably going to lose. Considering the likelihood and consequences of tire failure after cupping, youre best off replacing the cupped tire sooner rather than later.

Overhead camshaft engines use a timing belt to maintain a specific synchronization between the crank shaft and the camshaft. The belt turns the camshaft in harmony with the crankshaft to open and close the intake and exhaust valves at just the right time. Most vehicle manufacturers recommend replacing the timing belt as part of the normal maintenance schedule; however, the interval of this maintenance varies between vehicle manufacturers and ranges anywhere from every 65,000 to 100,000 miles .

Valve Timing

The camshaft has a number of lobes that push down on the exhaust or intake valve to let air into or exhaust out of the combustion chamber at just the right time. If the belt has slipped a tooth or broken, the engine will most likely stall as the intake or exhaust valves will no longer open and close at the proper times to let air in or out of the system.

Non-Interference Engines

If the timing belt breaks, the camshaft will cease to move and the valves will be stuck in whatever position they were in when the belt broke. Non-interference engines are designed so that the piston will not be able to contact the valve if the valve remains open when the piston is elevated to its highest position in its bore, so that no major internal damage can result.

Interference Engine

If your vehicle has an interference-style engine, then the camshaft timing is vital. In an interference engine, the intake or exhaust valves extend into the cylinder bore enough so that the piston will slam into the valve if the valve remains open too long. If the timing belt slips or breaks on an interference engine, the cost of repairs can be high, as the repair can involve having to replace the piston or valve.

Preventive Maintenance

To protect yourself from being stranded if the timing belt happens to break or jump a tooth, have the timing belt inspected regularly or become familiar with your vehicles timing belt inspection procedure and do it yourself on a regualr basis. If the engine in your vehicle has an interference engine, it is advisable to have the timing belt checked often and replaced on schedule to prevent the possibility of serious engine damage.

Automobiles, like many forms of life on Earth, long ago left the oceans for drier climes; and like most others evolved to land, autos arent particularly keen on going back to the depths. Whether or not a car runs after a good dunking partly depends upon the engine in question, partly on how much water it encountered, and why it stalled in the first place.

Puddles

Splashing through deep puddles -- those no deeper than about 6 inches, or slightly above the bottom of the oil pan -- is common enough that most manufacturers build cars to account for it. If a quick dunk into a puddle or a brief splash causes your engine to stall, then odds are water got into something electrical and shorted it. Most low-hanging sensors likely to encounter water -- the oxygen sensors and crankshaft position sensors -- arent prone to damage by it, but water in the will interrupt the signal they produce. Odds are good the car will start after you unplug the electrical connectors and dry them out.

Immersion Up to the Engine Block

Lets say you live in a flood-prone area and you wake up one morning to find your car standing in about a foot of water -- right up to the engine block or the bottom of the doors, but not past them. If the car refuses to start under these conditions, then its almost certainly because water has penetrated the lowest-hanging electrical connectors. The car may not start while its in standing water, but it should be fine afterward as long as the fuse block or computer hasnt gotten wet. Even a completely submerged computer may not be beyond saving as long as you dont send any power through it while it still is wet -- but dont count on it working after you dry it out.

Immersion Up to the Valve Covers

Unless you own a Jeep or a Hummer H1, immersion up to the valve covers is well beyond what the factory had in mind when they designed your car. If your car stalled while going through water up to the door handles or the bottom of the valve covers, you may have more significant problems than those electrical in nature. If it didnt stall because of an electrical short, then odds are that it stalled because water in the pipe created enough backpressure to halt the combustion process. Once the engine stalls, all of that pressure goes away and water comes flooding up through the exhaust system. At the very least, you may expect serious thermal shock damage to the catalytic converter core, and possibly a completely flooded engine.

Total Flooding -- Car vs. Submarine

In the above scenario, where the car stalled with water above the level of the exhaust ports in the engine, then water would flood up through the manifold and into the cylinders. Try to start the car with the cylinders full of water -- assuming the starter works -- and you end up permanently damaging the engine through hydro-lock. Once that happens, your engine is effectively toast. However, say the engine didnt stall until water got up past the intake system. In that case, youre looking at gallons of water sucked into the engine and almost certain hydro-lock. At that point, nothing can save it.

Salvaging the Vehicle

The good news is that as long as your engine didnt go into hydro-lock, theres no reason it shouldnt run after a thorough drying and replacement of the oil and any damaged electrical components. In cases of prolonged immersion, youll also need to drain the fuel tank and lines. Certain components, such as the computer, ignition module and possibly the ignition coil, are almost sure to go following immersion, but theyre replaceable. The guys at BBCs "Top Gear" television program proved this while attempting to destroy a diesel Toyota Hilux pickup truck by dropping it at the bottom of the English Channel and leaving it overnight. After a bit of drying, fluid replacement and electrical work, host Jeremy Clarkson started the truck and drove it home from the beach.

Until You See Grease Near Wheel Area

One of the first signs of CV joints going bad is when the caps of the CV joints break from the structure. This will cause grease to accumulate in the CV joint area, which is located between the front wheels of the car. If you see such an occurrence, take the car for maintenance immediately.

When You Hear Clicking and Popping Sounds

When the CV joints go bad, you will hear a popping or a clicking sound coming from the steering wheel. The more damaged the CV joints become, the louder and more intense the sound will be. Each time you turn the steering wheel, the clicking or popping sound will resonate. This indicates serious damage.

Bottom Line

CV joints can break easily and rapidly. Within a matter of weeks, the CV joints can become so bad that the maintenance cost will be very high. The sooner you fix the damaged CV joints, the lower the cost will be. Therefore, regularly examine the CV joint area to check for grease buildup. If you see no buildup, but begin to hear clicking or popping sounds, have the car fixed.