How to Check the Compression on an Aircooled Volkswagen (Vw) Beetle
Assemble the required tools: Compression tester A 13/16-inch spark plug socket.,Let the VW idle until the engine is completely warmed up., Turn off the engine and remove the spark plug connectors from each spark plug.,Remove all the spark plugs and...
Step-by-Step Guide
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Step 1: Assemble the required tools: Compression tester A 13/16-inch spark plug socket.
A ratchet (3/8-inch drive).
A 3-inch extension, 3/8-inch drive to reach cylinders #1 and #3.
A universal, 3/8-inch drive.
A 6-inch length of rubber breather hose, 1/2-inch ID. -
Step 2: Let the VW idle until the engine is completely warmed up.
, Mark each wire with masking tape so you can put them back on the correct plugs later. ,,, Be sure to turn the engine over six to eight times, same for each cylinder.
It is helpful to have a friend who can crank the engine.
Compression readings should be high compression (over 100 pounds) and relatively uniform among the cylinders (within 5 pounds).
Variations from cylinder to cylinder should be no more than 14 to 20 pounds. , If the compression reading increases a little, the problem is probably worn, broken, or poorly seated piston rings.
If the compression reading remains the same, leaking or damaged valves may be at fault. , Use the 6" rubber breather hose as an extension to hand-thread the plug into its hole.
Turn the spark plug a turn or so to ensure it is not cross threaded. , -
Step 3: Turn off the engine and remove the spark plug connectors from each spark plug.
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Step 4: Remove all the spark plugs and block the carburetor throttle so that it is fully opened.
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Step 5: Thread the compression gauge into a cylinder making sure that the pressure release button has been pushed and the reading is at 0.
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Step 6: Crank the engine for about 2 seconds and write down the highest reading from the gauge.
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Step 7: Recheck cylinders with low compression readings by injecting approximately 10cc of engine oil into the cylinder through the spark plug hole.
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Step 8: Return the spark plugs.
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Step 9: Reattached the spark plug wires.
Detailed Guide
A ratchet (3/8-inch drive).
A 3-inch extension, 3/8-inch drive to reach cylinders #1 and #3.
A universal, 3/8-inch drive.
A 6-inch length of rubber breather hose, 1/2-inch ID.
, Mark each wire with masking tape so you can put them back on the correct plugs later. ,,, Be sure to turn the engine over six to eight times, same for each cylinder.
It is helpful to have a friend who can crank the engine.
Compression readings should be high compression (over 100 pounds) and relatively uniform among the cylinders (within 5 pounds).
Variations from cylinder to cylinder should be no more than 14 to 20 pounds. , If the compression reading increases a little, the problem is probably worn, broken, or poorly seated piston rings.
If the compression reading remains the same, leaking or damaged valves may be at fault. , Use the 6" rubber breather hose as an extension to hand-thread the plug into its hole.
Turn the spark plug a turn or so to ensure it is not cross threaded. ,
About the Author
Kelly Edwards
Specializes in breaking down complex practical skills topics into simple steps.
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