Compression Pressure Inspection
Note. If the there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
Scheme 167
- Warm up the engine until the normal operating temperature becoming 80~95°C (176~203°F).
- Remove the surge tank.
- Remove the ignition coil connectors (A) and ignition coils (B).
- Using a 16mm plug wrench, remove the 6 spark plugs.
- Check cylinder compression pressure. Insert a compression gauge into the spark plug hole. Open the throttle fully. With the fully-open throttle in cranking, measure the compression pressure. NOTE: Always use a fully charged battery to get the engine speed of 250 rpm or more. Repeat steps 1 ) through 3 ) for each cylinder. NOTE: This measurement must be done in as short a time as possible. Compression pressure: 1,176.79kPa (12.0kgf/cm 2 , 170.68psi) - 200 ~ 250rpm Minimum pressure: 1,029.69kPa (10.5kgf/cm 2 , 149.34psi) Difference between cylinders: 98.07kPa (1.0kgf/cm 2 , 14.22psi) If the compression pressure in 1 or more cylinders is lower than the specification above, pour a small amount of engine oil into the cylinder through the spark plug hole, repeat the steps ( 1 ) through ( 3 ) for the cylinder and measure the pressure again. If adding oil increases the pressure up, the piston rings or cylinder bores might be worn or damaged. If the pressure doesn't increase, a valve may be sticking or seating may be improper, or there may be leakage from the gasket.
- Reinstall the spark plugs.
- Install the ignition coils and connect ignition coil connectors.
- Install the surge tank.
Troubleshooting
| Symptom | Suspect area | Remedy |
|---|---|---|
| Engine misfire with abnormal internal lower engine noises. | Worn crankshaft bearings. Loose or improper engine drive plate. | Replace the crankshaft and bearings as required. Repair or replace the drive plate as required. |
| Worn piston rings. (Oil consumption may or may not cause the engine to misfire.) | Inspect the cylinder for a loss of compression. Repair or replace as required. | |
| Worn crankshaft thrust bearings | Replace the crankshaft and bearings as required. | |
| Engine misfire with abnormal valve train noise. | Stuck valves. (Carbon buildup on the valve stem) | Repair or replace as required. |
| Excessive worn or mis-aligned timing chain. | Replace the timing chain and sprocket as required. | |
| Worn camshaft lobes. | Replace the camshaft and valve lifters. | |
| Engine misfire with coolant consumption. | Faulty cylinder head gasket and/or cranking or other damage to the cylinder head and engine block cooling system. Coolant consumption may or may not cause the engine to overheat. | Inspect the cylinder head and engine block for damage to the coolant passages and/or a faulty head gasket. Repair or replace as required. |
| Engine misfire with excessive oil consumption. | Worn valves, guides and/or valve stem oil seals. | Repair or replace as required. |
| Worn piston rings. (Oil consumption may or may not cause the engine to misfire) | Inspect the cylinder for a loss of compression. Repair or replace as required. | |
| Engine noise on startup, but only lasting a few seconds. | Incorrect oil viscosity. | Drain the oil. Install the correct viscosity oil. |
| Worn crankshaft thrust bearing. | Inspect the thrust bearing and crankshaft. Repair or replace as required. | |
| Upper engine noise, regardless of engine speed. | Low oil pressure. | Repair or replace as required. |
| Broken valve spring. | Replace the valve spring. | |
| Worn or dirty valve lifters. | Replace the valve lifters. | |
| Stretched or broken timing chain and/or damaged sprocket teeth. | Replace the timing chain and sprockets. | |
| Worn timing chain tensioner, if applicable. | Replace the timing chain tensioner as required. | |
| Worn camshaft lobes. | Inspect the camshaft lobes. Replace the timing camshaft and valve lifters as required. | |
| Worn valve guides or valve stems. | Inspect the valves and valve guides, then repair as required. | |
| Stuck valves. Carbon on the valve stem or valve seat may cause the valve to stay open. | Inspect the valves and valve guides, then repair as required. | |
| Worn drive belt, idler, tensioner and bearing. | Replace as required. | |
| Lower engine noise, regardless of engine speed. | Low oil pressure. | Repair as required. |
| Loose or damaged drive plate. | Repair or replace the drive plate. | |
| Damaged oil pan, contacting the oil pump screen. | Inspect the oil pan. Inspect the oil pump screen. Repair or replace as required. | |
| Oil pump screen loose, damaged or restricted. | Inspect the oil pump screen. Repair or replace as required. | |
| Excessive piston-to-cylinder bore clearance. | Inspect the piston, piston pin and cylinder bore. Repair as required. | |
| Excessive piston pin-to-piston clearance. | Inspect the piston, piston pin and the connecting rod. Repair or replace as required. | |
| Excessive connecting rod bearing clearance | Inspect the following components and repair as required. The connecting rod bearings. The connecting rods. The crankshaft pin journals. | |
| Excessive crankshaft bearing clearance. | Inspect the following components, and repair as required. The crankshaft bearings. The crankshaft main journals. The cylinder block. | |
| Incorrect piston, piston pin and connecting rod installation | Verify the piston pins and connecting rods are installed correctly. Repair as required. | |
| Engine noise under load. | Low oil pressure | Repair or replace as required. |
| Excessive connecting rod bearing clearance. | Inspect the following components and repair as required: The connecting rod bearings. The connecting rods. The crankshaft. | |
| Excessive crankshaft bearing clearance. | Inspect the following components, and repair as required. The crankshaft bearings. The crankshaft main journals. The cylinder block. | |
| Engine will not crank-crank shaft will not rotate. | Hydraulically locked cylinder. Coolant/antifreeze in cylinder. Oil in cylinder. Fuel in cylinder. | Remove spark plugs and check for fluid. Inspect for broken head gasket. Inspect for cracked engine block or cylinder head. Inspect for a sticking fuel injector and/or leaking fuel regulator. |
| Broken timing chain and/or timing chain and/or timing chain gears. | Inspect timing chain and gears. Repair as required. | |
| Material in cylinder. Broken valve Piston material Foreign material | Inspect cylinder for damaged components and/or foreign materials. Repair or replace as required. | |
| Seized crankshaft or connecting rod bearings. | Inspect crankshaft and connecting rod bearing. Repair as required. | |
| Bent or broken connecting rod. | Inspect connecting rods. Repair as required. | |
| Broken crankshaft. | Inspect crankshaft. Repair as required. |
TROUBLESHOOTING SYMPTOM CHART