what do you think about the ka24E
10-17-2005, 10:08 AM
#16
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Join Date: Aug 2005
Posts: 189
A compression tester will cost you about $20 from any auto parts store, and will last you a lifetime.
It's easy to use. Pull all the spark plugs, disconnect the ignition coil secondary wire (the one that goes from the coil to the distributor) and thread the compression tester fitting into the #1 cylinder's plug hole. Crank the engine over with the starter, letting the engine turn over a half-dozen times, then go look at the gauge and write down the reading. Every tester I've ever seen has a "hold" valve on it that automatically preserves the highest reading. Do this for all the cylinders, then compare readings. They should all be the same, within 10 percent or so, and since the battery will get drawn down a bit during the process, it's also normal for each cylinder to get progressively lower by a couple of PSI since the engine isn't turning over as fast.
If you have one cylinder that's a lot lower than the others (say, 135 psi, 132 psi, 90 psi, 134 psi) you know that there's a sealing problem with that cylinder.
You can diagnose what's wrong with the compression tester, too. If you re-do the test after squirting a little bit (like a teaspoon) of clean motor oil in through the spark plug hole and the pressure comes up, you know that the rings aren't sealing properly. If it stays low, you have a valve problem.
A leakdown tester also screws into the spark plug hole. It has two gauges on it, and a fitting to attach it to a source of compressed air. To use it, you turn the engine over by hand until you get the cylinder you want to check to top dead center on the compression stroke, then attach the leakdown tester and turn on the air. The gauges show the difference in pressure between what's being supplied and what's actually in the cylinder, indicating a percentage of "leakdown." It can also be used to diagnose problems by listening for air escaping into the crankcase (though the oil filler hole), intake manifold, or exhaust.
Leakdown testers are a lot more expensive ($100+) than a compression tester, though.
It's easy to use. Pull all the spark plugs, disconnect the ignition coil secondary wire (the one that goes from the coil to the distributor) and thread the compression tester fitting into the #1 cylinder's plug hole. Crank the engine over with the starter, letting the engine turn over a half-dozen times, then go look at the gauge and write down the reading. Every tester I've ever seen has a "hold" valve on it that automatically preserves the highest reading. Do this for all the cylinders, then compare readings. They should all be the same, within 10 percent or so, and since the battery will get drawn down a bit during the process, it's also normal for each cylinder to get progressively lower by a couple of PSI since the engine isn't turning over as fast.
If you have one cylinder that's a lot lower than the others (say, 135 psi, 132 psi, 90 psi, 134 psi) you know that there's a sealing problem with that cylinder.
You can diagnose what's wrong with the compression tester, too. If you re-do the test after squirting a little bit (like a teaspoon) of clean motor oil in through the spark plug hole and the pressure comes up, you know that the rings aren't sealing properly. If it stays low, you have a valve problem.
A leakdown tester also screws into the spark plug hole. It has two gauges on it, and a fitting to attach it to a source of compressed air. To use it, you turn the engine over by hand until you get the cylinder you want to check to top dead center on the compression stroke, then attach the leakdown tester and turn on the air. The gauges show the difference in pressure between what's being supplied and what's actually in the cylinder, indicating a percentage of "leakdown." It can also be used to diagnose problems by listening for air escaping into the crankcase (though the oil filler hole), intake manifold, or exhaust.
Leakdown testers are a lot more expensive ($100+) than a compression tester, though.
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