Let’s talk about testing compression
C@lvin » I did a forum search but couldn’t find anything. Could someone provide “how to” instructions or post a link to a procedure description? I picked up a compression gauge at Harbor Freight but the instructions that came with it, among other things, say it takes two people.
Also……I would appreciate instructions on a “leak down” test which I assume would use the same pressure gauge.
LamboSE5 » How do I disconnect the “positive lead from the coil”? I wanna make sure I do this test right. Does this mean the long “bougiecord” cord that leads from the distributor (and it’s 5 cords) to somewhere?
Here’s what I have:
Warm engine to operating temperature, and perform the following test after.
“Dry” test
1) Remove all 5 spark plugs.
2) Remove the fuel pump fuse, Unplug the Injectors (Just pop off that metal cover and disconnect each one) AND the Positive lead from the Coil.
3) Screw in the compression tester
4) With throttle fully open, turn the engine over 5-6 times (or about 7-8 seconds). After about a half dozen spins you should have a good compression reading. Make sure it’s within the specifications or within at least 10% or them.
Is there some other connector (electrical) I have to disconnect?
Geevs » Yes, the “positive” coil is the cord that runs from the ignition coil to the distributor. Just pull off the cord from the ignition coil as it is easier to access. Also remove fuse #2 from the fuse box located near the driver side windshield- this will disable the fuel pump. The purpose is to stop fuel delivery why you crank the starter several time during the compression test. Removing the ignition coil is just an additional safeguard.
Yes, I’m surprised at the consistent 180psi +/-2-3 psi across all cylinders for a 15 year old engine with 225K kms. That’s why I would like to have my compression tester tested. I bought this one
How can I test my engine’s compression?
You can do it yourself two ways: 1. if you have two gauges and a pressure regulator and 2. if you have a leakdown tester. Its better to have both testers. The leakdown tester helps pinpoint issues better than the compression gauge. But both are very useful in diagnosis. Click the link below to read the detailed instructions on testing your compression.
Check out the instructions here
Last Updated on February 3, 2022
