Repair And Fix it

The 2003 Buick Lesabre has a history of engine gasket failures. The intake manifold and oil pan gaskets are common replacement requirements that can cost you in excess of $700 to have repaired. Replacing the Positive Crankcase Ventilation Valve (PCV) can keep crankcase gases from building up in the engine and extend the life of the gaskets. The PCV valve is often overlooked as a maintenance item on this engine due to its location.

Instructions

1

Open the hood. Remove the oil filler cap. Remove the oil filler neck by twisting it counterclockwise until it releases. Remove the engine cover by lifting the front of it and pulling it towards you to release the rear mounting tap.

2

Locate the MAP sensor on the intake manifold towards the front of the engine. This sensor will have three wires- orange/black, light green, and grey. Lift the connector locking tab and remove the connector. Remove the MAP sensor by releasing the locking tabs with the screwdriver.

3

Remove the PCV valve cover under the MAP sensor by pressing a 5/8 -inch socket against it and twisting it counterclockwise a quarter turn. Remove the PCV valve and the O-ring. Wipe oil and debris from the mounting area.

4

Install the new PCV valve and O-ring by pressing it firmly into place. Install the PCV cover plate by pushing down on it with the socket and twisting it clockwise until it stops. Replace the seal on the MAP sensor if it is damaged. Install the map sensor slowly, taking care not to damage the mounting tabs. Snap the wiring connector into place.

5

Install the engine cover, making sure that the rear tab is inserted into the mounting bracket. Replace the seal on the oil filler neck if damaged. Install the oil filler neck. Install the oil filler cap.

The valve covers sit on the top of the cylinder heads, and removing them will allow you access to the valves, springs, rocker arms, and push rods on your 7.3-liter Powerstroke Diesel. The 1996 7.3-liter was an optional engine in the Ford F250 and F350 Super Duty series trucks. The engine is very durable and has a good torque band, allowing it to pull heavy loads with little to no stress to the engine.

Instructions

1

Open the hood of your Ford truck and locate the negative battery cable end on the battery terminal. Loosen the clamp bolt on the battery cable end with a wrench then remove the cable from the battery and move it aside, isolating it from the battery.

2

Locate the retaining bolts along the perimeter of the valve covers on the top of the engine. There are eight of them on each valve cover.

3

Remove the eight retaining bolts, one at a time, with a socket and ratchet. Set the bolts aside as you will need them later.

4

Slide a putty knife or other flat, stiff tool under the edge of the valve cover and pry the cover loose from the head. Lift the valve cover straight off the cylinder head and set it aside. Repeat the process on the second valve cover if you are removing both covers.

The exhaust gas recirculation valve, or EGR valve, is part of the Mercury Sables emissions control systems. EGR valves, which were introduced in the 1970s, are now included on all automobiles in the United States.

Purpose

The EGR valve, usually located on the intake manifold, reduces oxides of nitrogen (NOx) that form in internal combustion engines when temperatures reach 2,500 degrees Fahrenheit or more. Nitrogen and oxygen combine to form NOx, a component of smog.

Function

As its name implies, the EGR valve recirculates exhaust gases back into the combustion chamber. Because the exhaust gases cannot be burned again, the result is cooler temperatures in the combustion chambers---several hundred degrees cooler. This reduces the production of NOx.

Performance

The creation of the EGR valve has enabled auto engineers to design more aggressive timing for engines, increasing efficiency and, as a result, improving fuel economy. A malfunctioning EGR valve, however, leads to engine ping and knocking.

Inside a vehicles engine houses a myriad of intricately moving parts to propel the car forward. Parts, such as exhaust valves, play a key role in the functioning of the engines cylinder assemblies.

Function

Exhaust valves work inside the cylinder heads to function with the exhaust port, allowing fumes to leave the chamber. The valve itself runs extremely hot due to the lack of cooling from the hot exhaust fumes.

Identification

Exhaust valve problems arise more often than other valve problems because of the extreme heat, about 1200 to 1350 degrees Fahrenheit. Though it is made of strong alloy material, it can erode from burn-out, creating a hole in the side of the valve.

Considerations

Aside from being burned out, improper replacement of a valve can shorten its life. Additionally, excess deposits on the cylinder and valve can create a hotter environment to allow the erosion process to begin and hasten forward.

Changing the valve body in your 1994 Ford Bronco with automatic transmission can give you more control over the shift points of your transmission as well as fix valve body-related transmission problems. With the right tools, this is a job that can be accomplished in around three to four hours.

Instructions

1

Place wheel chocks in front of and behind one rear wheel. These can be 4-by-4-in. blocks. Jack the front end of the Bronco up enough that you can comfortably slide under the transmission area. Place the jackstands under both sides and caully lower the vehicle onto them.

2

Push the drain pan with the umbrella over it under the rear portion of the transmission where you can reach it from under the transmission pan. Bringing the tools, slide under the truck inline with the transmission pan.

3

Verify the correct socket size for the transmission pan bolts. Attach the correct socket to the end of the extension and the extension to the ratchet. It will be either the 7/16 or 1/2-in. socket.

4

Remove the three bolts from one corner by rotating them counterclockwise. Loosen the rest of the pan bolts halfway.

5

Slide the drain pan and umbrella under the transmission pan.

6

Insert the tip of the screwdriver between the pan and transmission case in the corner with the removed bolts and twist, breaking the seal of the gasket. Hold the pan umbrella and center the drain pan under the fluid flow. Wait for the flow to significantly slacken.

7

Remove the remaining bolts, slowly allowing the rest of the transmission fluid to flow out of the pan. Set the pan aside.

8

Remove the three screws holding the transmission filter in place and remove the filter, setting it into the pan umbrella.

9

Verify the size of the bolts securing the valve body and attach the correct socket to the extension. Rotate the bolts counter-clockwise to remove them. Set the bolts aside within easy reach. Set the valve body in the umbrella also.

10

Slide out from under the truck and clean the transmission pan with the parts cleaner and rags. Use the scraper to remove the gasket and through this away. Slide the pan and replacement parts and scraper under the truck and caully remove the drain pan.

11

Slide under the truck and use the gasket scraper to remove the gasket from the transmission case to pan mating surface.

12

Align the new valve body correctly and insert the bolts into the corresponding holes and start them by twisting them clockwise.

13

Attach the socket and ratchet to each bolt and tighten them to approximately 30 pounds per square inch of torque.

14

Align the new transmission with the bolts and fluid holes and insert the three retaining bolts. Twist these clockwise to start and tighten with the screwdriver.

15

Align the pan gasket with the bolt holes in the transmission pan. Use four to six bolts to hold the gasket in place and place the gasket and pan against the transmission case. Start the four or six bolts sufficiently to hold the pan in place by turning them clockwise.

16

Insert and start the remaining bolts. Run them all down to finger tight.

17

Tighten the bolts, moving from the center of each side of the pan to the corners. Torque the bolts to between 30 and 40 foot-pounds of torque. Slide out, bringing the tools with you.

18

Lift the truck off the jack stands and pull them out. Slowly lower the truck completely and pull the jack out.

19

Remove the transmission dipstick and insert the funnel in the opening. Caully pour four to five quarts in. Start the engine and allow the transmission to warm up. Shift gears every 10 to 15 seconds.

20

Place the transmission in park and check the fluid level. Pour enough fluid in for the reading to be full. Shift gears every minute or so again to ensure proper fluid flow.

A Chevy exhaust gas recirculation (EGR) valve is a necessary part of the cars emissions system. It works by rerouting some of the exhaust gases back into the intake manifold rather than into the atmosphere.

Types

There are several types of EGR valves with the same function but different modes of operation. Older EGR valves are purely mechanical and run on vacuum; on many newer Chevrolet and other GM models, the valve is controlled entirely by computer. This type uses multiple solenoids to open the valve in response to input from the cars computer, opening and closing the valve to allow exhaust gas flow.

Operation

Whether the EGR valve uses vacuum or electronic control, it opens when exhaust gases reach a certain temperature or level of backpressure. When the EGR valve opens, some of the exhaust is rerouted to the intake manifold. Since it is less combustible than the air-fuel mixture in the manifold, the temperature drops.

Functions

The main function of an EGR valve is to lower the amount of nitrogen oxide a car releases into the atmosphere. A failed EGR valve prevents a car from passing emissions testing, if required. The valves secondary function is to lower the temperature in the intake manifold.

The EGR, or exhaust gas recirculation, valve is a small metal disc bolted to the intake manifold near the carburetor on GMC trucks and vans. The EGR valve draws exhaust gases from the exhaust system and reintroduces them into the intake manifold. Introducing exhaust gases into the combustion chamber helps lower the combustion temperature of the engine, which in turn helps reduce the amount of harmful oxides of nitrogen (NOx) produced by the engine.

Instructions

Removing a GMC EGR Valve

1

Remove the air cleaner housing by unscrewing the wing nut on top of the air cleaner lid and lifting the air cleaner housing straight up until you clear the threaded rod.

2

Locate the EGR valve. It will be bolted to the intake manifold close to the carburetor.

3

Label and disconnect the vacuum line attached to the top of the EGR valve by pulling it off.

4

Remove the bolts that secure the EGR valve to the intake manifold.

5

Lift the EGR valve straight up to remove it from the intake manifold.

6

Use a flat razor blade to clean any gasket material of the EGR valve mounting surface.

7

Inspect the passages below the EGR valve, and use a flat blade screwdriver to clear away any carbon deposits.

8

Vacuum the area around the EGR valve mounting surface. Make sure none of the carbon deposits or loose gasket material is left behind. You dont want it to get sucked into the engine.

Installing an EGR Valve on a GMC

9

Place a new gasket on the EGR valve mounting surface.

10

Lower the new EGR valve into position on the intake manifold.

11

Reinstall the bolts that connect the EGR valve to the intake manifold.

12

Reconnect the vacuum line that attaches to the top of the EGR valve.

13

Reinstall the air cleaner housing by lowering it over the threaded rod above the carburetor and reinstalling the wing nut that secures it.

There are several different reasons for why O-rings can fail. Checking for damage is relatively easy. In most cases it is easy to tell that the O-ring does not look normal, but when you identify the exact characteristics, you will know what the problem is and will be able to take steps to fix it. The following four patterns are the most commonly found with O-rings and tells much about the solutions to fix them.

Instructions

1

Examine the O-ring by checking for compression set. This is when the seal lines have become deformed and compressed to the surface and look melted and misshapen. If this has not occurred, continue to the other steps until you can identify the problem. However if it has, it means the material of this O-ring was not suitable, or that the operating system temperature needs to be reduced.

2

Look for extrusion and nibbling. Its characteristics are a "torn," ragged look of the O-ring. This occurs in hydraulic rod and piston seals because of high pressure causing clearance gaps which destroy the ring. If this is the case, you may need to decrease clearance, ensure that the O-ring is tolerant of machine fluid, or replace the O-ring with a harder, more durable one.

3

Check for spiral failure if you have not seen the above two patterns. This looks like the O-ring has been twisted. This occurs when the seal becomes caught on one side but but is sliding and rolling on the other side. This can be fixed by improving surface finish, increased lubrication, or replacing the O-ring with a harder one.

4

Inspect for cracks or splits in the O-ring -- these are signs of explosive decompression. This happens when the O-ring has been operating under high pressure gas, which is then reduced quickly leaving gas trapped within the structure of the O-ring, causing ruptures. To avoid this, slow down decompression time, and select a sealant with resistance to decompression. If this is ineffective, replace the O-ring with a metal seal.

5

Examine the O-rings for abrasion.This looks like the O-ring has been scraped. This occurs when a proper surface finish is not being used. Inadequate lubrication is also a reason -- you may want to use internally-lubricated O-rings. You may need to install filters to avoid contamination of fluid.

The exhaust gas recirculation (EGR) valve in your 2000 Toyota RAV4 is an exhaust intake regulator attached to the intake manifold of the engine. First introduced in the early 1960s, it regulates the mixture of fuel and exhaust (oxygen) entering into the engines combustion chambers. It operates by allowing measured amounts of exhaust to enter the combustion chamber, thus reducing the temperature within the chamber during combustion. It has become a vital part in improving fuel efficiency and reducing smog.

Instructions

1

Open the hood and locate the EGR valve, which is mounted on the left-rear of the intake manifold near the firewall. Leave the battery plug in, but use precaution not to contact the posts with any tools.

2

Disconnect the air intake tube leading to the inside-left fender well and attached to the intake manifold. This will provide for better access for replacing the EGR valve.

3

Unplug the single-prong electrical connection from the EGR valve by hand. Disconnect the rubber vacuum tube and inspect both of these parts for excessive wear or cracking. Replace these parts as necessary.

4

Remove the two EGR mounting bolts located on the valve using a socket wrench. Gently tap the valve to break the seal using a hammer or rubber mallet. Remove the old EGR valve and scrape away the old gasket using a paint scraper. Be careful not to allow any debris to enter the engine block.

5

Apply a thin bead of high-temperature-resistant gasket sealer onto the new gasket. Place the gasket with sealant down, directly onto the manifold opening. Do not to disturb the gasket placement, which can cause a void. Be sure that the mounting bolt holes are properly aligned so that the replacement valve will seat and mount properly.

6

Carefully install the new EGR valve into the manifold opening. Secure the valve in place with the two mounting bolts. Reattach the rubber vacuum tube and the single-prong electrical connection. Reconnect the air intake tube.

7

Disconnect both battery cables using a crescent wrench, which will reset the electrical system and check-engine light indicator. Keep the battery disconnected for at least six hours before reconnecting it. Then reconnect the battery, start the engine and check to see if the check-engine light remains off. Test the repair by turning the vehicle off and on several times while observing if the check-engine warning light comes on.

The Exhaust Gas Recirculation (EGR) valve in your Ford Explorer is an exhaust regulating device attached to the intake manifold of the engine. It was first introduced to the United States in the 1960s and has continued to progress in improving fuel efficiency and reducing smog. It works by allowing small measured amounts of exhaust to enter the combustion chamber (pistons), thus reducing the temperature in the chamber. A malfunctioning EGR valve remains open and causes the temperature in the pistons to increase, allowing nitrogen oxide (smog forming emissions) to enter the atmosphere. Replacing the EGR valve in the Ford Explorer is a moderately easy repair to perform.

Instructions

1

Raise the hood and locate the EGR valve, which is attached to the right rear on the intake manifold near the firewall. The intake manifold is attached to the side of the engine block.

2

Disconnect the single-prong terminal electrical connection that plugs into the EGR valve sensor. Detach the black rubber vacuum tube which plugs into the EGR valve. Inspect the tube and electrical connection for cracking and excessive wear. Replace these parts as necessary.

3

Take out the two mounting bolts located on the top and bottom sides of the valve. Detach the old valve from the manifold and gently tap it using a hammer to break the seal. Scrape off the old gasket using a paint scraper, being careful not to allow any debris to enter the manifold.

4

Apply a thin coat of gasket adhesive to the new gasket using your finger and place it onto the manifold. Make sure the bolt holes are properly aligned so that the new EGR valve will seat properly.

5

Insert the new replacement EGR valve into the manifold opening being careful not to damage the EGR valve sensor attached on the top of the EGR valve. Secure the replacement EGR valve in place using the two bolts and reattach the single-prong terminal wire.

6

Disconnect the battery and wait 4-6 hours to reset the check engine light indicator. Reconnect the battery and see if the check engine light comes on again.

The cylinder heads in the four-stroke combustion engine have valves and valve seats that must be machined to precise tolerance and fit. If the valves do not seat correctly with their seats, they leak and lose compression. Valves that do not match within specifications with their seats can also cause excessive overheating and valve failure. The valve seat takes a continual pounding from the action of the valve when it closes. Valve seats can crack and become worn. Several tools need to be used to check and repair valve seats.

Crack Checking Tools

Before any valve seat can be reshaped and ground within specifications, the vale seat area must be magnafluxed to reveal hairline cracks. An electrical transformer attaches to the head, where it delivers a a high voltage magnetic charge to the metal. Magnaflux, which consists of a powdered, reactive chemical, gets sprinkled on the valve seat area. The chemical power reacts to breaks in the magnetic lines of force (field), which shows up as horizontal lines or spider-webbing cracks in the metal.

Valve Seat Grinding Machine

The valve seat grinding machine consists of of a platform vice that holds the cylinder head in a fixed and upright position. The vice fasteners lock the head into a level and stable orientation. The overhead part of the valve seat grinder consists of a motor that drives a cutting bit, which can be adapted to cut out the old valve seat from either aluminum or cast iron. A machine bit then cuts the new valve seat face at a precise angle, usually around 45 degrees. Dial indicators determine the depth of the cut, while bits determine the seat diameter to be cut. Lubricant, fed by the machine, keeps the cutting surface cool.

Valve Lappers

Valve lapping tools must be used to attain final sizing of the face and valve seats for a perfect, sealed match. The most common valve lappers consists of wood dowels that have two different size suction cups on each end. After the valve has been inserted in the stem and abrasive compound has been brushed between the valve face and the seat, a manual twisting motion turns the wood dowel back and forth to cut the interface seat between the valve and seat. Valve lappers come in a variety of suction cup diameters for intake and exhaust valves of all sizes.

Motorized Valve Lappers

Instead of manual wood dowel lappers, motorized drills and air guns can be fitted with suction cup bits that attach to the top of the valve. Once abrasive lapping compound has been applied between the valve and seat, the motor or air tool is turned on to spin the valve at high rpm. The use of power tools for lapping reduces the labor time involved in cutting the final seat and valve face.

Valve Seat Grinding Compound

Valve seat grinding compound consists of a a thick paste that contains cutting abrasives. The cutting compound comes in fine, medium and coarse grits. The coarse grit takes the most of the irregularities and burs out of the interface surfaces, while the medium and fine cutting compound cuts the last finishing face between the valve and valve seat.

Having properly functioning exhaust valves is an important part of automobile maintenance as poorly functioning exhaust valves can lead to excessive oil consumption, compression leaks, valvetrain noise and total valve failure. Exhaust valves are more susceptible to burning because they run hotter than the intake valves, averaging between 1,200 and 1,350 degrees Fahrenheit. Most of the time when exhaust valves are burned, they will cause losses in compression. Therefore, a good way to test for a burned exhaust valve is to run a compression test or leak-down test.

Ignition Misfire

A misfire can sometimes be an indication of a burned exhaust valve. Typical signs of a misfire include the engine shaking at idle, steering wheel vibration, or if the engine is difficult to start or stalls at start up. If this is happening, it could mean a loss of compression, which occurs when the cylinder has lost a large part of its air and fuel mixture before being ignited. If not a blown head gasket, misfires due to loss of compression usually mean there is a burned exhaust valve.

Power Loss

Power loss can be another indication of a burned exhaust valve. This is also linked to ignition misfires since a misfiring cylinder can sometimes cause up to 25 percent power loss. If your automobile is losing power, it could mean the exhaust valve is burned.

Puffing or Puttering Sound

A burned exhaust valve will often make noises that sound like a puff or putter. ImperialClub.com refers to it as a "chuff-chuff." These sounds go off each time the cylinder tries to fire. EconoFix.com points to a trick where car owners can hold a dollar bill and let it flap over the exhaust pipe. If it gets sucked in every so often, it is likely a burned exhaust valve.

Failed Emissions Test

If the exhaust pipe is burned, the engine will blow hydrocarbons out of the tailpipe. This will cause many vehicles to fail an emissions test. If your car has recently failed such a test, it could be a symptom of a burned exhaust valve.

The positive crankcase ventilation (PCV) valve on the 2006 Chrysler Town and Country regulates the ventilation of gases within the engine. When the PCV valve fails, emissions and gases may pass back into the engine instead of being locked into the exhaust system. Buy a replacement valve from a Chrysler dealer or auto parts specialty store and change it in seconds, saving the labor costs and the lost time spent in a service centers waiting room.

Instructions

1

Raise the hood of the vehicle. Locate the PCV valve on the top center of the valve cover.

2

Pull the hose off the top of the PCV valve. Pull the valve straight out of the valve cover.

3

Insert the new PCV valve straight into the valve cover. Push the rubber hose onto the top of the new PCV valve until it stops. Close the hood.

The transmission vacuum modulator valve determines how much load is on the engine so the transmission can shift properly. It has a vacuum line that connects to the intake and measures the amount of vacuum in the engine.

High Load vs. Low Load

In order to determine if whether transmission should shift, the modulator valve measures the load of the engines vacuum. Engine load is the measurement of how hard an engine works at any given moment. For example, coasting down hill will create a low engine load, while driving uphill with two passengers and a trunk full of luggage will create a high load. Thus, shift points for the transmission are figured according to the valves measurement.

How It Works Within the Transmission

The modulator valve is a part of the transmission vacuum. Inside the canister of the vacuum modulator, the valve works with a diaphragm and a calibrated spring to measure load. When the diaphragm senses changes in engine vacuum because of load changes, the diaphragm pushes against the valve while the calibrated spring moves against the movement of the diaphragm.

Potential Problems

If the modulator valve is not working properly, the transmission will not shift properly. These problems can arise when the hose connecting the transmission to the engine vacuum cracks or burns, or collapses onto itself.

The first EGR valves were installed in engines in 1973, and these valves are still a staple in nearly all engines in 2010. The EGR valve is one of the many components used to control emissions. EGR is an acronym for "Exhaust Gas Recirculation."

Function

The main function of the EGR valve is to reduce the amount of nitrogen oxides (NOx) released into the air. The EGR valve prevents the release of NOx by recirculating cooled exhaust gases into the combustion chamber.

Effects

The EGRs cooling effect keeps the combustion chamber below 2800 degrees Fahrenheit. This temperature reduction limits the chemical reaction between nitrogen and oxygen, thus reducing NOx emissions.

Mechanics

Pre-electronic vehicles had vacuum-controlled EGR valves, while cars from 1996 and later use an electronic EGR. The mechanics of either valve are exactly the same. At idle, the EGR is fully closed and remains closed until warm-up. After warm-up, the EGR slowly opens as the engine speed increases, providing a cooling effect as the stress on the engine builds.

The PCV valve is one the most important aspects of the emissions control system. The valve recirculates unburned gases and fresh air into the crankcase, allowing for cleaner burning of the fuel. The PCV valve is a simple plastic valve that flexes with the pressure of the engine, allowing for more or less unburned gases to pass through. The 2006 Ram 1500 followed similar designs with the placement and operation of the PCV valve. You should check the valve every 30,000 miles, and replace it, as necessary.

Instructions

1

Trace the air filter tubing. The PCV valve connects to this, remotely, through black tubes.

2

Trace the black vacuum tubes to the PCV valve. The tubing may route through the brake booster on some models.

3

Pull the tube off of the PCV valve, to verify you have located it properly. The 3.7L and 4.7L PCV valves mount directly onto the oil fill spout. The 5.7L places the PCV valve directly on the intake, behind the throttle body. The PCV valve is a basic plastic component about two inches in length. Some are L-shaped.

The valve train linkage is a basic necessity of a combustion engine. To understand the workings of an engine, you must first understand how the fuel and air make their way to the cylinder where they are combined.

Valve Train Function

The valve train consists of the valves and the camshaft in your engine. The valves open and close to allow air and fuel into the cylinder, and then to allow exhaust out of the cylinder. The camshaft is a rotating metal rod with different sized bumps along its length. This rod lifts and drops the valves according to cylinder and combustion order as it turns.

Linkage Function

The valve train linkage is the part or parts that attach the camshaft to the valves themselves. Some engines have valves that sit directly on the cam, others have rods and lifters that link the two parts.

Considerations

As in most mechanical things, fewer parts means less potential for problems. This would make the direct or short linkage engine preferable to an engine with a complicated valve train linkage. Many older cars were built with the more complicated system.

Exhaust gas recirculation valves, better known as EGR valves, minimize your car engines creation of nitrous oxide, which can be harmful to the environment. EGR valves play a crucial part in cutting down on the creation of smog. EGR valves help to reduce the overall temperature of the engine by introducing a portion of exhaust gas back into the combustion chambers. The exhaust gas takes the place of otherwise combustible material (air and gasoline), thereby causing cooler combustion temperatures while still generating the same force to push the piston. EGR valves can reduce smog creation by as much as 60 percent. Several major types of EGR valves exist.

Single Diaphragm EGR Valves

Single diaphragm EGR valves are the oldest and simplest type of EGR valve. They consist of a spring-loaded diaphragm connected to a pintle and seat by a slender steel shaft. Vacuum is ported into the diaphragm, which causes the pintle to pull off of its seat. The removal of the pintle from its seat results in the exhaust being allowed to flow into the valve chamber and the intake manifold.

Positive Back Pressure EGR Valves

Positive back pressure EGR valves have a much thicker pintle shaft than a single diaphragm valve. They also usually have a "P" stamped next to the part number and date code. The pintle shaft on these EGR valves is hollow, and it is the play between this hollow control valve and a control valve that regulates vacuum flow that causes the valve to work. Exhaust gases flow into the shaft itself and push up on the shaft, which it turn seals the built-in control valve. Vacuum pressure pulls on the diaphragm and causes it to open.

Negative Back Pressure EGR Valves

Negative back pressure EGR valves can be identified by the "N" stamped next to the date and the part number. It looks very similar to a positive back pressure EGR valve. This EGR valve is opened by a combination between applied engine vacuum and negative exhaust system impulses. When the pintle opens, back pressure is reduced. This reduction causes the control valve vacuum bleed to open and a valve to close. The negative exhaust pulses help to regulate the flow of gas.

Integrated Electronic and Mechanical EGR Valves

An integrated electronic and mechanical valve can be identified by its single vacuum source inlet and three-wire electrical connector. Its basic operation is similar to a single diaphragm EGR valve except for a small pintle position sensor atop its diaphragm. This sensor communicates with the power control module, which in turn applies vacuum when necessary by signaling a pulse width modulated solenoid.

Cummins diesel engines are a common engine option in full-size Dodge trucks. The six-cylinder, 5.9-liter Cummins engine has four valves per cylinder for a total of 24 valves. The gasket between the cylinder head and the engine block forms a tight seal between these two components. A leaking head gasket can cause the oil in the vehicle to have a milky appearance when it becomes contaminated by coolant.

Instructions

1

Place a clean container beneath the radiator, and open the drain cock with a socket wrench. Allow the coolant to drain into the pan, and save the coolant for reuse. Disconnect the cable from the negative battery terminal so you dont start the engine during the procedure.

2

Detach the accessory drive belt from its pulleys, and remove the alternator from the engine compartment with a socket wrench. Disconnect the air cleaner from the intake manifold. Remove the crankcase ventilation system and evaporative emissions system from the engine.

3

Remove the fuel lines from the fuel rail with a socket wrench. Disconnect the cables for the accelerator, cruise control and transmission to obtain access to the intake manifold. Remove the distributor cap with the electrical wiring still attached, and detach the electrical wiring from the ignition coil.

4

Detach the electrical connector from the engine coolant temperature sensor. Disconnect the water bypass hose and upper radiator hose from the engine to access the intake manifold. Remove the intake manifold and valve covers from the engine with a socket wrench.

5

Record the original position of the valve train components, including the rocker arms, push rods, exhaust manifolds and spark plugs. This ensures you can install these components in the correct position later. Remove the valve train components from the engine with a socket wrench.

6

Remove the mounting bolts for the cylinder head, and lift the cylinder heads from the engine block. Discard the gasket on the engine block.

7

Turn the crankshaft clockwise so that the timing marks for the crankshaft and camshaft do not align. This ensures that no piston is in the top dead center position when you install the cylinder head. Wait five minutes for the lash adjusters to depressurize before installing the cylinder head.

8

Place a new cylinder head gasket on the engine block, and mount the cylinder head on top of the gasket. Tighten the mounting bolts for the cylinder head to 50 foot-pounds with a torque wrench on the first pass and 105 foot-pounds on the second pass.

9

Install the valve train components to their original positions, using the notes you made in step five as a guide. Replace the additional components you removed to access the cylinder head by performing steps two through four in reverse.

10

Connect the cable for the negative battery terminal, and replace the coolant in the cooling system. Start the engine and check for fluid leaks.