Repair And Fix it

If you have a Chevrolet car or truck made between 1967 and 1997, theres a good chance it has a 350-cubic-inch engine. The Chevrolet 350 small-block engine was offered in many Chevrolet cars and trucks and in other General Motors vehicles as well. The 350 became Chevrolets primary work-horse small-block engine after the demise of the 327 and 283 engines. The 350 is identified using both visual clues and casting numbers.

Instructions

1

Count the number of spark plugs. The 350 is an eight-cylinder engine

2

Inspect the engine compartment to locate identification tags. GM usually places various tags, decals and other identification devices throughout the engine compartment. These usually provide any necessary information if it is not worn off.

3

Locate the casting identification number on the engine block. This number is stamped on a pad just forward of the right-side (passengers side) cylinder head and may be hidden by the alternator. Remove the alternator if necessary. The ID number usually consists of eight digits in a combination of numbers and letters.

4

Decode the ID number according to Chevrolets code system. For example, the number V0908CNJ breaks down as follows: V is the engine plant, followed by the month and day of manufacture and the engine suffix code. ID number V0908CNJ was manufactured at the Flint engine plant on October 8 and was originally installed in a 1970 Caprice with 250 horsepower. To decode the engine suffix, cross-referencing is necessary.

Engines incorporate a basic but complex dance of physics, harnessing and converting energy in a multi-stage process to turn dead dinosaurs into forward velocity. The fuel molecules journey through an engine may not qualify as epic to us, but it is fairly Odyssean by subatomic standards.

Into the Engine

Fuel starts out as a liquid stored in the fuel tank. A pump shoves fuel through a line and into a filter, which gets rid of any debris that may clog the injectors. After going through the filter, fuel travels upstream to the fuel injectors. Fuel injectors work just like the spray nozzle on your garden hose, and spray out in much the same way as a garden hose nozzle on "fine mist." When you just crack the hose aperture open, pressure in the line forces water to spray out in a fine, cone-shaped mist. With an injector, this mist goes into the engine just ahead of the intake valve in multi-point fuel injected engines; on direct-injection engines, it sprays directly into the combustion chamber.

Into the Cylinder

Next, the intake valve opens and low pressures in the cylinder -- caused by a piston dropping down in the cylinder on its "intake stroke" -- suck air and fuel mist (atomized fuel) into the combustion chamber. Modern engines generally use a high-swirl cylinder-head design, which allows the air to maintain velocity and swirl like a tornado around the cylinder instead of just rushing in and slamming into a wall. This tornado effect increases power by allowing more air and fuel to fill the cylinder, and it enhances efficiency by keeping fuel suspended as a fine mist instead of allowing it to coalesce into fat droplets. This more even distribution allows more of the fuel to burn and produce power.

Boom

The intake valve closes just as the piston rises on its "compressions stroke," which (as you might guess) compresses the air and fuel into a small pocket above the piston called the combustion chamber. A spark goes off in the top of the chamber just before the piston reaches the very apex of its travel. The compressed air and fuel around the spark ignite, starting out as a tiny "flame kernel" and quickly expanding out into a bubble known as the "flame front." This bubble travels at or near the speed of sound, quickly expanding to fill the cylinder and shoving the piston back down with the force of its expanding gases and the power of its own sonic shockwave. This is the "power stroke."

The Combustion Event

Combustion is any event wherein fuel combines with oxygen to produce heat and some sort of chemical conversion. Gasoline is a hydrocarbon, meaning that its made of hydrogen and carbon atoms (commonly one carbon atom and four hydrogen atoms). When this CH4 molecule combines with O2 (oxygen gas), it produces CO2 (carbon dioxide), H20 (water) and heat. So, a pure hydrocarbon in a pure oxygen atmosphere would hypothetically produce only carbon dioxide and water. However, air is about 78 percent nitrogen by volume, and under extreme heat and pressure that nitrogen also combines with oxygen to produce dangerous nitrogen oxide emissions. Additionally, oxygen is almost always the limiting reactant in this chemical reaction, so a certain amount of fuel will leave the engine unburned during the exhaust stroke.

Combustion Malfunctions

Fuel doesnt always expand in a neat flame kernel, or front, away from the spark plug. The compressed air-fuel mixture is extremely volatile, and almost anything will set it off. This is especially true of low-octane fuels, which ignite easier than high-octane fuels. Too much heat and pressure inside the cylinder or combustion chamber will cause the fuel to auto-ignite, or "detonate." Detonation -- aka "knock or "ping" -- is extremely bad because its an explosion rather than a controlled burn, effectively identical to grilling a chicken with dynamite. These explosions happen in multiple places around the cylinder, and each one produces its own sonic shockwave. When those shockwaves collide, they instantly spike cylinder pressure and pre-ignite any remaining fuel caught between them. This kind of uncontrolled chaos is death for any engine, particularly forced-induction powerplants using a supercharger, turbo or nitrous.

Automobile jargon can be confusing to the layperson, especially when costly repairs or replacements are being considered to a vehicles engine. Understanding the different terms can help the consumer make an educated decision during a purchase.

Identification

A rebuilt engine is an engine that has portions that are repaired and cleaned, but also contains parts that are deemed satisfactory by the rebuilder, and allowed to function without cleaning or adjustment. A remanufactured engine is one that has been overhauled by the original manufacturer to meet their basic specifications, adjusting and cleaning the entire engine.

Considerations

Rebuilt engines tend to be less expensive, due to the fact that less labor was put into the item, and many repair shops recommend them so their repair estimates stay relatively low.

Helpful Tip

Choosing a remanufactured engine may cost more money upfront, but may save money in the long run, as they tend to be more reliable engines with longer lifespans.

Nissan is a Japanese auto manufacturer. Until 2008, Nissans V6 engine had appeared in every single annual publication of "Wards 10 Best Engines." "Wards Auto World" magazine began publishing the list in 1995. If you are considering trading your engine for a Nissan engine or if you want to upgrade your existing Nissan engine, its smart to do a comparison to find which one is best for you. To effectively compare Nissan engines you need to have a set of comparison criteria.

Instructions

1

Decide what is most important to you in an engine. If youre upgrading or replacing a damaged engine, you should establish exactly what size of engine is suitable for your car. Take account of power and performance. For example, the 2002 3.5-liter Nissan Maxima is capable of delivering an impressive 255 horse power. Consider mileage, cubic capacity, age and weight. Putting a heavy engine in a small car can cause handling problems. The engines in Nissans VQ engine range are aluminum and are relatively light. Write down the three most important criteria for your engine comparison.

2

Discount engines that dont meet your criteria. If you are looking for a cheap replacement engine for an old Nissan, dont spend lots of money on a high-performance GTS engine. The 2.5-liter 2003 Nissan Altima and Nissan Sentra were recalled due to temperature fluctuations that caused the engines to shut down. Be wary of engines that have been subject to manufacturer recall.

3

Use impartial reviews and manufacturer specifications to supplement your comparisons. You should use your key criteria to make comparisons, but note any other beneficial features to help you decide between two similarly suitable engines. Something as simple as the location of the seller may be enough to swing the deal one way or the other.

4

Make a short list of three engine types that youve identified as suitable. Make your ranking process more precise by using a higher grading threshold for the criteria you determined most important: Rank each engine according to your three main criteria. Allow 1 to 20 points for each engine youre considerings proficiency in your top criterion. Allow 1 to 10 points for each engines proficiency in your second most important criterion, and allow 1 to 5 points each engines proficiency in the third.

5

Take account of the cars the engines were in previously. For example, Nissans SR20DET engine is used in various Nissan cars, including the DT Turbo, the Bluebird and the Silvia (these are Japanese versions of Nissan cars). An engine powering a lighter car will have less wear per mile than the same engine powering a larger car. Its the same method of operation you would use if you had two identical cars but one had been used to tow a trailer: You would dock points for engine wear on the engine that towed the trailer due to the extra weight the car pulled and the extra effort the engine exerted.

First released in 1978 and spanning three generations, Mazdas rotary-powered RX-7 grew to become one of the most easily recognizable and sought-after sports cars to come from Japan. Now out of production, the RX-7 is not only enjoyed by enthusiasts, but is also competitive in several classes of racing. With its single-minded philosophy and emphasis on performance, the 13B-REW (the motor designation of the last production model) is able to crank out 255 horsepower, all from a minuscule 1.3-liter twin-rotor Wankel engine bolstered by sequential twin-turbos. The drawback of this design -- and power output -- is the extreme heat and stress to which engine components are subjected, in some cases requiring expensive rebuilds after just 60,000 miles. The engine can be quite finicky to troubleshoot.

Instructions

1

Attach an engine code reader to the Mazdas diagnostic port to quickly identify any faulty components.

2

Tune up the vehicle by installing new filters (oil, air, fuel) and replacing vital engine fluids. Pay special attention to the engine coolant -- which should have no traces of dirt or oil. If you are experiencing any sort of hesitation, rough idle, or inconsistent power delivery, thoroughly inspect and replace any worn ignition components such as the ignition coil, igniter module and spark plugs/wires. This can cure a myriad of symptoms and prevent new ones from developing.

3

Install a new set of silicone vacuum lines (silicone withstands heat better and stays more flexible). The stock lines will often become cracked or brittle due to prolonged exposure to heat, causing erratic boost levels and idle surge.

4

Connect a data-logger unit to your vehicle in order to further investigate engine conditions. The data-logger is able to read values directly from the engine control unit, and displays a list of vital parameters in real time. This will help identify pre-ignition (knock) events, as well as display the various timing and fuel maps under varying engine loads.

5

Attach a multimeter to your battery and alternator to test for correct voltages. Low readings (under 12 volts) indicate a weak system, potentially making the vehicle difficult to start, or even causing a backfire through the exhaust.

Purchasing a rebuilt engine or having your car serviced with a tear-down and rebuild of its existing engine involves a significant outlay of money. However, the option is still cost-effective when compared to the price of a new car. Rebuilt engines dont just plug in and work reliably once purchased. Many parts and systems from the existing car need to be integrated with the rebuilt engine, and the process can introduce unexpected problems.

Quality is as Good as the Mechanic

Rebuilt engines depend significantly on the labor process. If the mechanic is knowledgeable about the engine, the likelihood is good the repair will be reliable. If its the mechanics first time with an unfamiliar engine, problems in assembly may occur.

Assembly replacement engines are built under factory specifications and are put together following set criteria on the assembly line. The error rate of a bad engine tends to be fairly small.

Part Issues

After-market replacement parts do not always have the same quality tolerances as the original parts. These inferior parts will break down faster, even in rebuilt engines.

Labor Costs

Rebuilt engines are not likely to work perfectly, but the owner bears the responsibility for the cost of the service and rebuild, even if the engine has problems later on.

Even without mechanical issues, a rebuilt engine is expensive. The average car mechanic labor cost runs between $80 to $100 per hour. This includes the complete tear-down and then rebuild, not to mention replacement parts.

Warranty Issues

Some rebuilt engines purchased as assemblies are only covered for up to 90 days on a warranty basis.

More common, shop warranties on service rebuilt engines tend to be three years or 36,000 miles, if all instructions are followed on care and maintenance. However, some shops will rebuild engines with warranties lasting in some cases as much as 100,000 miles.