| MOXIE | -- 01-20-2010 @ 3:41 PM |
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I did a compression test on my 21 stud engine due to a ticking sound the engine was making. All cylinders except for one was around 70 to 75 pounds. The odd one was 55 pounds. What does this mean. A bad piston, broken ring, sticking valve. Like I said it makes a ticking sound when it idels and when I rev it up..
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| TomO | -- 01-20-2010 @ 5:17 PM |
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Moxie, try using a screw driver as a stethoscope to isolate the ticking sound. If it is louder at the top of the head or the intake manifold, It is probably a valve not operating correctly. This can be due to sticking, the guide keeper (horseshoe clip) not in the correct slot or not seated or excessive clearance between the valve and the lifter. Sticky valves can be helped by adding Marvel Mystery Oil to your gas and using a high detergent oil. MMO can be added to the oil pan and the car driven at speeds that do not exceed 40 mph for a few miles. Tom
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| 37RAGTOPMAN | -- 01-21-2010 @ 9:19 AM |
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HI what happens when you have it running and disconnect that spark plug wire with the low compression, does it miss with it running, or makes no difference when you disconnect the wire,? a ticking valve could also be a broken valve spring,but you should have a miss,and one cylinder not working,[ but it could come and go,] I would try some MMO ,in a spray down the carb , at a high idle and see if it makes it run any different, do this outside, because of the SMOKE, HOPE this HELPS, 37RAGTOPMAN
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| 37RAGTOPMAN | -- 01-21-2010 @ 9:20 AM |
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HI what happens when you have it running and disconnect that spark plug wire with the low compression, does it miss with it running, or makes no difference when you disconnect the wire,? a ticking valve could also be a broken valve spring,but you should have a miss,and one cylinder not working,[ but it could come and go,] I would try some MMO ,in a spray down the carb , at a high idle and see if it makes it run any different, do this outside, because of the SMOKE, HOPE this HELPS, 37RAGTOPMAN
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| supereal | -- 01-21-2010 @ 10:33 AM |
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Do a "dry/wet" compression test. Remove all spark plugs. Block the throttle open and run a compression test on the low cylinder, and write it down. Then, squirt at least a couple of tablespoons of oil into the cylinder. It can be motor oil or MMO, etc, then re-run the test. If the compression substantially increases, the rings are at fault, possibly a broken ring. If the compression doesn't increase to any extent, a valve(s) is leaking. As mentioned, it could be a broken or weak spring, an out of place keeper, or a burned valve face or seat. In most cases, sticky valves are not confined to one cylinder, and pouring anything down the carb just makes smoke when a valve stem is carboned up. I suspect you will find a spring problem. A few months ago, a car came in with a noise and a low cylinder. It tuned out to be a loose valve seat that someone didn't fit correctly.
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