DIPLOMA TEKNOLOGI AUTOMOTIF

PRINCIPLE OF ENJIN 2

TAJUK TUGASAN:TOP OVERHAUL

NAMA PENSYARAH:SIR.RIDHWAN

NAMA PELAJAR :CEAROLL PENLIUS

KAD MATRIK :KYS081 DTA0011

NO.I/C :900608-12-5869

KELAS :DTA 2

How To: do a Compression Test

1. Before you begin, make sure the battery is fully charged. Take it for a good hard drive. 5 minutes of idling won’t cut it.

2. Pull the MPI (MultiPort Injection) fuse on the positive terminal of your battery. This cuts power to the injectors so they don’t spray gas all over the place.

3. Unplug the coil connector, it’s on the right side, at the back of the block. You could get a nasty shock if you don’t.

4. Remove all 4 plugs and examine them carefully for signs of a problem. If your valve seals are bad in any cylinder, the plug will be fouled to some degree. Signs of oil on the plugs could indicate a ring problem.

5. Screw the compression gauge into the plug hole

6. Press the gas pedal to the floor to open the throttle plate, and keep it at WOT (wide open throttle) for as long as you’re cranking (if you didn’t pull the MPI fuse, there would be a bit of a mess, now).

7. Turn the ignition to the ON position, and hold it there for a count of four revolutions (do not

turn the key on-and-off four times). On each rotation, the gauge needle will jump slightly less than the previous one.

Update: It may take more than 4 revolutions to get a stable reading; crank for up to 10 seconds or until the needle stabilizes, whichever comes first.

Note: If your battery is weak, the engine will turn over slower and give you lower readings.

8. The last number the gauge jumps to is the compression for that cylinder.

9. Repeat for each cylinder.

Compression specifications

=> 14 psi maximum difference between cylinders

1G (90-94) T/E/L 1.8L NT engine 2.0L NT engine2.0L Turbo engine

Compression ratio 9.0:1 9.0:1 7.8:1Standard compression

185 psi 192 psi 164 psi

Service limit 131 psi 145 psi 121 psi

2G (95-99) T/E2.0L NT 420A engine

2.0L 4G63 Turbo engine

2.4L NT Spyder engine

Compression ratio 9.8:1 8.5:1 9.5:1Standard compression

170-225 psi 178 psi 192 psi

Service limit 100 psi 133 psi 146 psi

Galant (89-93) SOHC 8v engine SOHC 16v engineCompression ratio 8.5:1 9.5:1Standard compression

178 psi 185 psi

Service limit 125 psi 139 psi

Galant (89-93) DOHC pre-91 NT DOHC 92+ NT DOHC Turbo

engine engine engineCompression ratio 9.0:1 9.8:1 7.8:1Standard compression

192  psi 220 psi 164 psi

Service limit 137 psi 159 psi 114 psi

10. In this picture you might not be able to make out the number ... but ... cylinder 2 is losing compression big-time!

All a "wet test" entails is a bit of oil in the low cylinder...

11. Add one capful (1-2 tablespoons) of oil to the cylinder with low compression.12. Let it sit for a minute to allow the oil to flow down and coat the sides of the cylinder and piston. If there are any gaps in the rings, the oil will seal them for the next few minutes.

13. Crank the engine for 4 revs, remembering to floor the throttle.

14. If the reading improved significantly (more than 30 psi), your rings are probably worn.

15. If there is little or no improvement, take it to a garage that can perform a leak-down test to determine where the compression is escaping (intake, exhaust, crankcase, gasket, etc.).

16. Replace the plugs, preferably in the same cylinders they came out of. You may want to clean or re-gap them first, or put in new ones. A dab of anti-seize on the threads would be a

good idea.

17. Remember to put the MPI fuse and coil connector back. You’re not going anywhere without them!

How to do a Compression Test

A compression test is an easy way to determine the internal health of your engine. You can pay a dealership $50 to do it for you, or you can do it yourself in about 10-15 minutes. Here's how...

You will need:

compression gauge

You can get one of these for between $15 and $50 almost anywhere you can get auto supplies, including Canadian Tire, Pep Boys, and even WalMart. You don't need a particularly good or expensive one just to make sure you're in spec.

13/16" spark plug socket

Obviously, and a socket wrench, to take out the spark plugs.

Optional, but recommended:

4 new NGK BPR6ES spark plugs

In case any of the plugs are fouled. The NGK are the most frequently recommended plugs on the Talon Digest by Club DSM members, so who am I to argue?

plug gapping tool If you're not replacing your plugs, and even if you are, you might as well make sure they're properly gapped.

oil and a funnel In case you need to do the wet test.

What will a compression test tell me?

It will tell you if your engine has good compression. An engine is essentially a self-powered air pump, so it needs good compression to run efficiently, cleanly and to start easily.

As a rule, most engines should have 140 to 160 lbs. of cranking compression with no more than 10% difference between any of the cylinders.

Low compression in one cylinder usually indicates a bad exhaust valve. Low compression in two adjacent cylinders typically means you have a bad head gasket. Low compression in all cylinders would tell you the rings and cylinders are worn and the engine needs to be overhauled.

Checking Compression

Compression can be checked two ways: manually with a compression gauge or electronically with an engine analyzer. The manual gauge method is the only one available to most do-it-yourselfers.

To check compression, all the spark plugs are removed. The ignition coil is then disabled or the high tension lead is grounded. The throttle is also held open. The engine is then cranked for a few seconds using a remote starter switch or a helper while a compression gauge is held in a spark plug hole. The maximum compression reading is noted, then the process is repeated for each of the remaining cylinders. The individual cylinder readings are then compared to see if the results are within specs (always refer to a manual for the exact compression specs for your engine because they do vary from the ballpark figures we quoted earlier).

If compression is low in one or more cylinders, you can isolate the problem to the valves or rings by squirting a little 30 weight motor oil into the cylinder through the spark plug hole and repeating the compression test. The oil temporarily seals the rings. If the readings are higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings tells you the cylinder has a bad valve.

With electronic testing, a computer analyzer "estimates" compression in each of the engine's cylinders by measuring slight variations in engine cranking speed. The results correlate well with actual gauge readings and can be completed in a matter of minutes without having to remove any spark plugs. What's more, the analyzer prints out the results of the compression test making it easy to see and compare the actual numbers.

How to Check Your Engine's Compression

As a technician, I am frequently asked questions related to Engine Compression. My responses have been formulated below and will help any mechanic, (D.I.Y. or professional) to fully comprehend the importance of compression. The information below will guide you through a basic compression test and diagnostic routine.

For your own safety, it is advised that you purchase and follow the correct auto repair literature before attempting this process. The following text only describes general information and is not vehicle specific. This text does not express or imply any vehicle specific directions.

Q. What is compression in an engine, and how does it work?A. Compression is a process in which air or an air/fuel mixture is confined and pressed into a smaller volume within the area of an engine's cylinder. This process forces all of the molecules to be "pressed" together under high pressure.

In the case of a gasoline engine, moderate compression is required, 140 to 160 pounds per square inch (psi). Some engines may require as much as 220 psi depending on their size and application; the manufacturer gives specific compression specifications. If the compression in a gasoline engine is too high, it can cause a problem known as preignition or detonation. This can be very destructive, causing damage to the internal parts of the engine. However, a diesel engine requires very high compression, usually 350 psi or more because it relies on this compression process to ignite the diesel oil. Diesel engines are much heavier and louder compared to the gasoline engine. This compression process, combined with an air/fuel mixture and a source of ignition, is what produces the necessary power to operate vehicles of all types.

Q. When should the compression be checked on a vehicle?A. Generally speaking, the compression should be checked in any instance when an engine is running roughly or is lacking power. Most manufacturers and technicians believe it is important to perform a compression test every time a tune-up is done as part of preventative maintenance; consult your vehicle owner's manual for tune-up intervals. By performing a compression test, internal engine malfunctions, such as bad valves, piston rings or excessive carbon buildup, can be detected before they cause irreparable damage. It benefits the owner to be aware of these problems so they can make an informed decision whether to invest in repairs or sell the vehicle.

Q. How is the engine compression checked?A. Engine compression is checked in different ways for different vehicles. In this section, I will only cover the general information required for testing a gasoline engine. Diesel engines require specialized equipment and will not be covered here.

Compression on a gasoline engine can be tested in two ways. The first method involves using a manual, handheld compression gauge.

Make sure the engine has been warmed up before beginning the test, to ensure that the oil has been warmed up. A cold engine will not test correctly.

Disable the ignition module or coil.

Insert the compression tester into one cylinder spark plug hole at a time.

Hold the throttle to full open position to ensure the engine gets adequate air intake.

Crank the engine continually for at least five to 10 full revolutions to obtain an accurate reading on the compression tester.

Record the reading for each cylinder. If any of them vary 10 percent or more from each other a problem may exist in one or more cylinders. If the variance is greater than 10 percent, specialized testing equipment may be required to fully diagnose the problem.

If all cylinder readings are within 10 percent of each other, no further testing is required and compression is considered optimal.

The second method of testing involves the use of an electronic engine analyzer. The analyzer 'shorts' one cylinder at a time with the engine running and calculates the rpm drop. Once all cylinders are measured, a reading is given that will show which cylinders are working the hardest

(have the most compression) and which are working the least (have the least compression). For the do-it-yourselfers, the easiest method is the manual compression test.

Q. What if thecompression is too low or too high?A. If the compression results are too high or too low, you might consider consulting a professional technician. Modern vehicles are complicated to test and I have witnessed disastrous outcomes when a Do-It-Yourselfer has attempted this test. If however, you are fearless in your endeavor to diagnose the problem, then use the following techniques.

Consecutive low compression in all cylinders could mean that the problem of fuel washed cylinders exists. This means that the engine has had too much fuel introduced into it and all of the oil has been washed off the cylinder walls. The oil creates a sealing effect between the piston and ring assemblies and the cylinder walls of the engine block. Without this thin layer of oil, the engine compression would be allowed to escape into the crankcase. This is common with an engine that has a 'flooding' problem.

If the engine seems to run normally but is weak and puffs a small amount of bluish smoke, it could be an indicator of worn piston rings and cylinder walls. In either of these events, use a small oil can and squirt a little oil into each cylinder, then repeat the compression test. If the compression dramatically increases then you have found the problem(s). If the compression readings do not change, then it would indicate a timing problem between the camshaft(s) and the crankshaft of the engine. The timing chain or belt would need to be checked for proper timing.

If you find the compression reading is very low or zero in one cylinder, it is highly probable that internal engine damage exists such as:

The piston could have a broken connecting rod or a hole in it. A valve could be stuck or leaking.

There could be a broken valve spring or a bent push rod.

The camshaft has excessive wear and is not opening the valve(s).

If the compression is low or zero on two adjacent cylinders, it would indicate:

There is a 'blown' or weak sealing surface at the head to block mounting area, which basically means a bad head gasket.

The camshaft is broken in an area that operates valves for two adjacent cylinders.

When the compression is found to be too high in one or more cylinders, this would be an indication of excessive carbon buildup in the engine. It can only be corrected by performing a chemical de-carbonizing process on the engine or by removing the cylinder head(s) and physically removing the carbon that is attached to the cylinder portion of the head(s) and the tops of the pistons.

TORQUE WRENCH

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A torque wrench is a tool used to precisely apply a specific torque to a fastener such as a nut or bolt. It is usually in the form of a socket wrench with special internal mechanisms. A torque wrench is used where the tightness of screws and bolts is crucial. It allows the operator to measure the torque applied to the fastener so it can be matched to the specifications. This permits proper tension and loading of all parts. A torque wrench indirectly measures torque as a proxy for bolt tension. The technique suffers from inaccuracy due to inconsistent or uncalibrated friction between the fastener and its mating hole. Measuring bolt tension (bolt stretch) is more accurate but often torque is the only practical means of measurement.

[edit] Beam type

Beam type torque wrench. The indicator bar remains straight while the main shaft bends proportionally to the force applied at the handle.

Detailed view of the torque display scale on a beam type torque wrench. This shows a torque of about 160 inch pounds or 17 newton metres.

The simplest form of torque wrench consists of a long lever arm between the handle and the wrench head, made of a material which bends elastically in response to applied torque. A second, smaller bar with integral mechanical indicator is also connected to the head; this is never subjected to torque and thus maintains a constant position with respect to the head. When no torque is applied to the lever arm the indicator rests parallel to the lever arm. A calibrated scale is fitted to the handle so that applied torque, and the associated bending of the main lever, causes the scale to move under the indicator. When the desired torque is reached (as shown by the indicator), the operator stops applying force. This type of wrench is simple, inherently accurate, and inexpensive.

The beam type torque wrench was developed in the late 1920s/early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.

A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual indication, or electrical indication, or both when a preset torque is reached.

Deflecting beam

The dual-signal deflecting beam torque wrench was patented by the Australian Warren and Brown company in 1948. It employs the principle of applying torque to a deflecting beam rather than a coil spring. This helps prolong wrench life, with a greater safety margin on maximum loading and provides more consistent and accurate readings throughout the range of each wrench. The operator can see and hear when a dual-signal wrench reaches the selected torque, since the signal can be seen and heard.

Click type

Click-type torque wrench, with a socket attached, adjusted by turning the knurled handle

A more sophisticated method of presetting torque is with a calibrated clutch mechanism. At the point where the desired torque is reached, the clutch slips, signaling the desired torque and preventing additional tightening. The most common form uses a ball detent and spring, with the spring preloaded by an adjustable screw thread, calibrated in torque units. The ball detent transmits force until the preset torque is reached, at which point the force exerted by the spring is overcome and the ball "clicks" out of its socket. The advantage of this design is greater precision and a positive action at the set point. A number of variations of this design exist for different applications and different torque ranges. A modification of this design is used in some drills to prevent gouging the heads of screws while tightening them.

"No-hub" wrench

This is a specialized torque wrench used by plumbers to tighten the clamping bands on "hubless" soil pipe couplings. It is a T-handled wrench with a one-way combination ratchet and clutch, factory calibrated to slip at a torque sufficient to seal the coupling, but insufficient to damage it. Since the ratchet is not reversible, the shaft of the wrench incorporates a folding auxiliary handle for loosening the clamps.

Electronic torque wrenches

Electronic torque wrenches

With electronic (indicating) torque wrenches, measurement is by means of a strain gauge attached to the torsion rod. The signal generated is converted by the transducer to the required unit of force (N m, lbf.ft etc.) and shown on the digital display. A number of different joints (measurement details or limit values) can be stored. These programmed limit values are then permanently displayed during the tightening process by means of LEDs or the display. At the same time, this generation of torque wrenches can store all the measurements made in an internal readings memory. This readings memory can then be easily transferred to a PC via the interface (RS232) or printed straight to a printer. A popular application of this kind of torque wrench is for in-process documentation or quality assurance purposes.

Programmable electronic torque / angle wrenches

programmable electronic torque / angle wrench

Torque measurement is conducted in the same way as with an electronic torque wrench but the tightening angle from the snug point or threshold is also measured. The angle is measured by an angle sensor or electronic gyroscope. The angle measurement process enables joints which have already been tightened to be recognised. The inbuilt readings memory enables measurements to be statistically evaluated. Tightening curves can be analysed using the software via the integrated tightening-curve system (force/path graph). This type of torque wrench can also be used to determine breakaway torque, prevail torque and the final torque of a tightening job. Thanks to a special measuring process, it is also possible to display the yield point (yield controlled tightening). This design of torque wrench is highly popular with automotive manufacturers for documenting tightening processes requiring both torque and angle control because, in these cases, a defined angle has to be applied to the fastener on top of the prescribed torque (N m) (e.g. 50 N m + 90° - here the 50 N m means the snug point/threshold and +90° indicates that an additional angle has to be applied after the threshold).

Saltus-Werk Max Forst GmbH applied in 1995 for an international patent for the first electronic torque wrench with angle measurement which did not require a reference arm.

[edit] Mechatronic torque wrenches

mechatronic torque wrench

Torque measurement is achieved in the same way as with a click-type torque wrench but, at the same time, the torque is measured as a digital reading (click and final torque) as with an

electronic torque wrench. This is, therefore, a combination of electronic and mechanical measurements. All the measurements are transferred and documented via wireless data transmission.

Differences between types

Click type torque wrenches are precise when properly calibrated—however the more complex mechanism can result in loss of calibration sooner than the beam type, where there is little to malfunction. Beam type torque wrenches are impossible to use in situations where the scale cannot be directly read—and these situations are common in automotive applications. The scale on a beam type wrench is prone to parallax error, as a result of the large distance between indicator arm and scale (On some older designs). There is also the issue of increased user error with the beam type—the torque has to be read at every use and the operator must use caution to apply loads only at the floating handle's pivot point. However, for inherent accuracy, the beam (P.A. Sturtevant / Chrysler Engineering) type wins hands-down[citation needed]: As long as the pointer is free to move, and rests at zero (or is bent to achieve this), 100% accuracy is inherent -- no matter how shoddy, rusty, dinged, etc., the tool may appear. Dual-beam or "flat" beam versions reduce the tendency for the pointer to rub, as do low-friction pointers.

For the click type, when not in use, the force acting on the spring should be removed by setting the scale to 20% of full scale in order to maintain the spring's strength. Never set a micrometer style torque wrench to zero as the internal mechanism requires a small amount of tension in order to prevent tool failure due to unwarranted tip block rotation. If a micrometer tool has been stored with the setting above 20% the tool should be set to 50% of full scale and exercised at least 5 times before being used. In the case of the beam type, there is no strain on the component that provides the reference force except when it is in use, therefore, accuracy is inherent.

See also

Electronic torque wrench one too

User Any operator trained in torque and angle tightening

Description - Torque tightening can be programmed or directly read - Angle tightening can be programmed or directly read - Both Torque & Angle can be programmed for single tightening operation - Once a value is programmed, tightening is controlled via an audible beep starting at 50% of the target setting - Wrench is protected from torque overload

Hydraulic torque wrench TorcUPA TorcUP Hydraulic Torque Wrench is a tool designed to exert torque on a fastener to achieve proper tightening or loosening through use of hydraulics. A torque wrench is applied to the nut either directly or in conjunction with an impact socket. Hydraulic torque wrenches directly apply a predetermined, controlled amount of torque to a properly lubricated fastener, eliminating the guess work necessary with stud tensioning and turn of the nut methods of bolting. Hydraulic torque wrenches also dramatically increase worker safety and efficiency.

TorcUP Inc. TU Series Features

*Patented Mono-Body Housing This feature allows for direct reaction against the housing of the tool, as well as significant reduction in housing flex and torsion.

*Dual Independent Swivels 360 degree by 360 degree swivels allow for individual movement of duplex hoses. Steel construction adds durability.

*Push Through Square Drive Change the direction of the tool from loosen to tighten by pushing the Vascomax square drive through the tool.

*Laser Engraved Torque Chart The torque chart for the square drive tool is laser engraved directly on the shroud to allow for quick reference. It also reverses from Ft/lbs- PSI to Nm-Bar.

*Quick Connect Couplers

*Body Material The TU Series housing is manufactured from 7075 Aircraft Quality lightweight alloy.

*U.S. Patent No. 6,068,068

TOP OVERHAUL

1.Tentukan jenis enjin

2.Keluarkan coolant dan minyak enjin

3.Tanggalkan komponen yang rosak

4.Tanggalkan rokcer arm(aci jumpelang)

5.Tanggalkan cylinder head

-Periksa permukaan head

-Periksa keadaan camshaft

-Periksa valve stem dan valve guide

-Jalankan valve lapping dengan betul.

6.Pasang semula head

-Pasang semula nut menggunakan torque wrench

-Ketatkan cylinder head mengikut spesifikasi dan urutan yang betul.

7.Memasang semula rocker.

-Tetapkan valve timing dan memasang timing belt.

- Laraskan kelegaan valve.

8.Isikan semula coolant dan minyak pelincir mengikut kuantiti.

9.Hidupkan enjin dan periksa jika ada kebocoran atau tiada.

10.Tune enjin mengikut spesifikasi yang ditetapkan.

-Menggunakkan alat peniun

-Lakukan analisa ekzos,timing light dan tachometer.

Rumusan top overhaul

-Top overhaul adalah salah satu penyervisan enjin pada bahagian head.

-Ianya dilakukan dengan memeriksa semua komponen pada bahagian head sahaja.

-Ini sangat penting untuk memastikan enjin sentiasa dalam keadaan baik.

RUJUKAN.

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