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Toyota Corolla Cylinder Compression Test
The following cylinder compression test procedures are applicable to the following Toyota Corolla models:
Engine Type: DOHC inline 4-cylinder engines with 4 valves per cylinder
1.3 liter (1332 cc) Non-VVT-i engines (engine code 4E-FE)
1.4 liter (1398 cc) VVT-i engines (engine code 4ZZ-FE)
1.6 liter (1587 cc) Non VVT-i engines (engine code 4A-FE)
1.6 liter (1598 cc) VVT-i engine (engine code 3ZZ-FE)
NOTE: The following models listed above where produced in 1998, 1999, 2000, 2001 and 2002. Never attempt to perform any repair procedures without a repair manual for your specific vehicle, additional data and safety precautions may be included.
Compression pressure specifications: Minimum: 10.0 bar (1 bar = 14.50326 psi). Maximum difference between cylinders: 1 bar
A compression test on your Toyota Corolla will provide diagnostic evidence as to the engines performance condition. In cases where misfiring or lacking performance cannot be linked to the ignition or fuel system, a compression test can pinpoint the cause of the problem. By performing a compression test on regular intervals, it will provide early warning of trouble before symptoms become irreparable or costly.
Before performing a compression test on your 4-cylinder Toyota Corolla, be sure to fully warm the engine to normal operating temperatures. The battery must be fully charged before the compression check procedure is initiated. A helper is also needed to aid in the procedure.
Remove the number 10 fuel pump fuse from the fusebox in the engine compartment. If possible, turn the engine on and allow the motor to run until the excess fuel in the fuel system burns off, the car will then stall.
WARNING: Damage to the catalytic converter could result by failing to allow the residual fuel in the fuel system to burn off.
Remove the spark plugs and connect the compression tester to cylinder number one spark plug hole. Its recommended to use a compression tester that screws into the spark plug thread. Also note any recommended instructions ,including safety precautions provided with the compression tester.
Have the helper support the throttle to the wide open position, then crank the engine on the starter motor. Crank the engine and allow for one or two revolutions, the compression pressure will begin to build-up on the gauge and then begin to stabilize. Note the readings obtained from the gauge. Repeat the compression test on the remaining three cylinders, be sure to record the compression pressure for each additional cylinder.
Upon completion, all cylinders should yield nearly identical pressure readings. Any cylinder showing more than 1 bar (1 bar = 14.50326 psi) between any two cylinders is a strong indication of problems. On a healthy engine, the compression pressure should build-up fast. On a motor with worn piston rings the compression will be low on the first stroke and slowly increase on additional compression strokes. If on the first stroke a low compression reading is obtained, followed by low compression readings on successive strokes, this indicates a possible blown head gasket, leaking valves or a cracked cylinder head. Excessive deposits underneath the valve heads can also cause a low cylinder compression reading.
If the cylinder compression is low, apply a teaspoonful of clean motor oil into that cylinder through that spark plug hole. Then, repeat the compression test for that cylinder.
If the application of motor oil improves the compression pressure temporarily, this is a strong indication that the piston wear or bore is to blame for the cylinder compression loss. Burnt or leaking valves or a blown head gasket can be ruled out as the cause.
Need to download a factory repair manual? Click here
http://www.inboardrepairmanual.com/?p=551
If a low compression reading is obtained from two adjacent cylinders, its most likely a result of a blown head gasket between those to cylinders. Inspect the engine coolant for a brown "milky" color substance in the cooling system; this is an indication of motor oil in the cooling system confirming a blown head gasket.
If a compression reading is 20 percent lower than all other cylinders, this is an indication of a worn camshaft lobe. A worn camshaft lobe will also cause the engine to idle rough.
If the compression reading is abnormally high, the combustion chambers are mostly likely coated with heavy amounts of carbon deposits. If the combustion chambers are coated with heavy carbon deposits, and all other factors have been ruled out, remove the cylinder head and de-carbonise the head.
Upon completing the compression test, reinstall the spark plugs and reinstall the fuel pump fuse.
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