‘Wet’ Engine Compression Test
A low or zero compression test result is usually due to one of two conditions: worn/damaged cylinder head valves or worn piston rings in the affected cylinder.
The good thing is that you and I can find out by adding about two tablespoons of oil to that cylinder and repeating the compression test.
In a nutshell, this is how this wet compression test works: If the low compression value is due to worn piston rings, the engine oil (that you're gonna' add) will bring the compression value up to normal. If the problem is due to cylinder head valves, the oil isn't gonna' help at all.
OK, this is what you need to do:
Add a small amount of engine oil to the cylinder that reported low compression or no compression in the ‘Dry’ compression test.
- The amount should be about 1 to 2 tablespoons of oil.
Install the compression tester onto the cylinder.
- Do not use any type of tool to tightened the compression tester... hand tight is fine.
When all is set up, have your helper crank the engine.
- You'll get one of two results, either the compression value will go up (from the one you recorded before) or it will stay the same.
CASE 1: The compression value shot up.. This confirms that the low compression this cylinder registered in TEST 1 is due to worn piston rings.
CASE 2: The compression value DID NOT go up.. This tells you that the cylinder head valves are behind the low or no compression value you registered in TEST 1.
Which Compression Tester Should I Buy?
There are lot of engine compression testers to choose from and many places to buy them. I'm gonna' make two recommendations to you:
1) Which one to buy: The engine compression tester that I have always used is the Actron CP7827 Compression Tester Kit. My only complaint about this engine compression tester is that it does not come with a case to store it in.
Engine Compression Gauge Testers
2) Where to buy: You can buy an engine compression tester just about anywhere, but you'll end up paying more for it (especially at your local auto parts store). The above links will help you comparison shop. I think you'll agree it's the better way to save money on the compression tester!
Related Test Articles
You can find all of the 1.5L Honda articles here: Honda 1.5L Index of Articles.
Here's a sample of the tutorials you'll find in the index:
- How To Test The MAP Sensor (Honda 1.5L).
- How To Test The Fuel Injectors (1992-1995 1.5L Honda Civic).
- How To Test The Throttle Position Sensor (1992-1995 1.5L Honda Civic).
- How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at: easyautodiagnostics.com).