Engine Compression Test and Cylinder Leakage Test
- Engine Compression Test: NOTE: After this test, you must reset the engine control module (ECM)/powertrain control module (PCM). Otherwise, the ECM/PCM will continue to stop the fuel injectors from operating.
- 1. Warm up the engine to normal operating temperature (cooling fan comes on twice).
- 2. Turn the ignition switch to LOCK (0).
- 3. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC).
- 4. Turn the ignition switch to ON (II).
- 5. Make sure the HDS communicates with the vehicle and the ECM/PCM. If it does not communicate, troubleshoot the DLC circuit.
- 6. Select ALL INJECTORS STOP in the PGM-FI, INSPECTION menu with the HDS.
- 7. Turn the ignition switch to LOCK (0).
- 8. Remove all ignition coils.
- 9. Remove all 4 intake spark plugs.
- 10. Attach a compression gauge to the spark plug hole of the No. 1 cylinder.
- 11. Hold the throttle fully open, then crank the engine with the starter motor and count the compression strokes required to reach maximum compression (normally between 6-10).
NOTE: If the compression gauge does not hold pressure, check for a missing or damaged Schrader valve in the cylinder side of the compression gauge adaptor hose, or in the gauge pressure bleed off port.- 12. Record the compression value below, and then measure the compression on the remaining cylinders using the same number of compression strokes. Record their values below.
Minimum Compression Pressure:
135 psi (930 kPa) Maximum Variation:
29 psi (200 kPa) Variation Example
Highest Reading Max Variation Lowest Reading Variation 210 psi 29 psi 170 psi 40 psi Is the compression and their variation are OK?
YES
The engine compression and all cylinder compression value's variation are OK. Go to step 2 (Cylinder Leakage Test).
NO
Record the compression test result, then go to step 2 (Cylinder Leakage Test).
- Cylinder leakage test (No. 1 cylinder):
If the piston is not exactly at top dead center, applying air pressure to the cylinder will rotate the crankshaft. Be certain to remove your tools from the crankshaft, and stay clear of any potential rotating parts when applying the test pressure to the cylinder. Make certain that the vehicle is in P or N with the parking brake set.
NOTE:- Ensure that the Schrader valve is removed from the cylinder side of the adaptor hose. All of your readings will show 0 % leakage if the valve is left in place during testing.
- Disconnect any shop exhaust hoses from the vehicle. The vacuum from these hoses may cause an incorrect diagnosis.
- 1. Remove the cylinder head cover.
- 2. Set the No. 1 piston at top dead center (TDC). The "UP" mark (A) on the camshaft sprocket should be at the top, and the TDC grooves (B) on the camshaft sprocket should line up with the top edge of the head.
- 3. Insert the adaptor hose into the No. 1 spark plug hole, and connect the hose to the cylinder leakage tester. Record the cylinder leakage for the No. 1 cylinder. (The cylinder leakage tester must also be connected to shop air.)
Is the leakage greater than 10 %?
YES
The cylinder leakage is too high. Listen for escaping air in each of these areas: throttle body (fully open), exhaust pipe, radiator (cap removed), and rocker area. Record the area where the majority of the air is escaping. Go to step 3.
NO
The cylinder leakage is acceptable, Go to step 3.
- Cylinder leakage test (No. 3 cylinder):
If the piston is not exactly at top dead center, applying air pressure to the cylinder will rotate the crankshaft. Be certain to remove your tools from the crankshaft, and stay clear of any potential rotating parts when applying the test pressure to the cylinder. Make certain that the vehicle is in P or N with the parking brake set.
NOTE:- Ensure that the Schrader valve is removed from the cylinder side of the adaptor hose. All of your readings will show 0 % leakage if the valve is left in place during testing.
- Disconnect any shop exhaust hoses from the vehicle. The vacuum from these hoses may cause an incorrect diagnosis.
- 1. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °). For "R" series engine, align the No. 3 piston TDC groove (A) on the camshaft sprocket with the top edge of the head.
- 2. Insert the adaptor hose into the No. 3 spark plug hole, and connect the hose to the cylinder leakage tester. Record the cylinder leakage for the No. 3 cylinder.
Is the leakage greater than 10 %?
YES
The cylinder leakage is too high. Listen for escaping air in each of these areas: throttle body (fully open), exhaust pipe, radiator (cap removed), and rocker area. Record the area where the majority of the air is escaping. Go to step 4.
NO
The cylinder leakage is acceptable. Go to step 4.
- Cylinder leakage test (No. 4 cylinder):
If the piston is not exactly at top dead center, applying air pressure to the cylinder will rotate the crankshaft. Be certain to remove your tools from the crankshaft, and stay clear of any potential rotating parts when applying the test pressure to the cylinder. Make certain that the vehicle is in P or N with the parking brake set.
NOTE:- Ensure that the Schrader valve is removed from the cylinder side of the adaptor hose. All of your readings will show 0 % leakage if the valve is left in place during testing.
- Disconnect any shop exhaust hoses from the vehicle. The vacuum from these hoses may cause an incorrect diagnosis.
- 1. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °). For "R" series engine, align the No. 4 piston TDC groove (A) on the camshaft sprocket with the top edge of the head.
- 2. Insert the adaptor hose into the No. 4 spark plug hole, and connect the hose to the cylinder leakage tester. Record the cylinder leakage for the No. 4 cylinder.
Is the leakage greater than 10 %?
YES
The cylinder leakage is too high. Listen for escaping air in each of these areas: throttle body (fully open), exhaust pipe, radiator (cap removed), and rocker area. Record the area where the majority of the air is escaping. Go to step 5.
NO
The cylinder leakage is acceptable, Go to step 5.
- Cylinder leakage test (No. 2 cylinder):
If the piston is not exactly at top dead center, applying air pressure to the cylinder will rotate the crankshaft. Be certain to remove your tools from the crankshaft, and stay clear of any potential rotating parts when applying the test pressure to the cylinder. Make certain that the vehicle is in P or N with the parking brake set.
NOTE:- Ensure that the Schrader valve is removed from the cylinder side of the adaptor hose. All of your readings will show 0 % leakage if the valve is left in place during testing.
- Disconnect any shop exhaust hoses from the vehicle. The vacuum from these hoses may cause an incorrect diagnosis.
- 1. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °). For "R" series engine, align the No. 2 piston TDC groove (A) on the camshaft sprocket with the top edge of the head.
- 2. Insert the adaptor hose into the No. 2 spark plug hole, and connect the hose to the cylinder leakage tester. Record the cylinder leakage for the No. 2 cylinder.
Is the leakage greater than 10 %?
YES
The cylinder leakage is too high. Listen for escaping air in each of these areas: throttle body (fully open), exhaust pipe, radiator (cap removed), and rocker area. Record the area where the majority of the air is escaping. Go to step 6.
NO
The cylinder leakage is acceptable, Go to step 6.
- Cylinder leakage result check:
Record your test results in a chart similar to the one below.
Cylinder Leakage (%) Leakage Area No. 1 No. 2 No. 3 No. 4 Does any cylinder have leakage greater than 10 %?
YES
Go to step 8.
NO
Go to step 7.
- Cylinder compression result check.
Check your cylinder compression results.
Does the compression vary more than 29 psi between cylinders, or does any cylinder read below 135 psi?
YES
The engine compression is low and cylinder leakage is normal. Check for each of these conditions:
Low Compression Inspection Area One cylinder low Worn cam lobes Broken valve springs VTEC engines (stuck rocker pins) Bent connecting rod All cylinders read low Worn piston rings Timing belt/chain off a tooth (valve timing) Faulty timing belt/chain tensioner NO
The engine compression and cylinder leakage is normal. Remove the cylinder leak-down gauge from the spark plug hole. Reinstall the cylinder head cover, the spark plugs and the ignition coils.
- Leakage area check:
Check your cylinder leakage results.
Is the majority of the air escaping from the exhaust pipe or throttle body?
YES
Go to step9.
NO
Compare your test results (leakage area) to the chart below, and inspect/repair the associated components as needed.
Leakage Area Inspection Area Rocker, oil cap, dipstick tube, breather tube Piston rings Cylinder walls Radiator (bubbles in coolant) Head gasket Engine block Cylinder head - Valve clearance check:
Check the valve clearances on the problem cylinder(s).
Are the valve clearances OK?
YES
Compare your test results to the chart below, and inspect/repair the associated components as needed.
Leakage Area Inspection Area Throttle body Intake valves Exhaust pipe Exhaust valves NO
Adjust the valve clearance, then go to step 10.
- Cylinder leakage check:
Recheck the leakage on the cylinders with high leakage.
Is the cylinder leakage within specifications?
YES
The cylinder leakage is normal. Remove the cylinder leak-down gauge from the spark plug hole. Reinstall the cylinder head cover, the spark plugs and the ignition coils.
NO
Compare your test results (leakage area) to the chart below, and inspect/repair the associated components as needed.
Leakage Area Inspection Area Rocker, oil cap, dipstick tube, breather tube Piston rings Cylinder walls Throttle body Intake valves Exhaust pipe Exhaust valves Radiator (bubbles in coolant) Head gasket Engine block Cylinder head