Hey folks, I have a question for you, about compression readings.
From what I've been told over the years, the correct way to take a compression reading is to warm the engine up a bit, remove all the spark plugs, (or glow plugs if diesel) make sure the battery is fully charged, make sure the fuel is turned off, and then take the readings.
When the engine is cranked, it encounters the cylinder being tested, and the pressure builds. You get an instant reading on the compression gauge. Then it spins around and the piston comes up for the second compression stroke, and the reading goes a little higher on the gauge. then it happens a third time, and so on. Each time it spins and encounters the cylinder being tested, the incremental increase on the gauge becomes smaller. finally, after about 10 or 12 spins, it's maxed out.
For my diesel engine, I got numbers around the following:
first spin: 280 psi
second spin 380 psi
third spin 450 psi
twelfth spin 480 psi
These numbers were pretty consistent in all 6 cylinders.
So my question is this: what is the correct "compression reading" for the cylinder? I can't seem to find an answer to this question by doing web searches.
thanks
Dana
From what I've been told over the years, the correct way to take a compression reading is to warm the engine up a bit, remove all the spark plugs, (or glow plugs if diesel) make sure the battery is fully charged, make sure the fuel is turned off, and then take the readings.
When the engine is cranked, it encounters the cylinder being tested, and the pressure builds. You get an instant reading on the compression gauge. Then it spins around and the piston comes up for the second compression stroke, and the reading goes a little higher on the gauge. then it happens a third time, and so on. Each time it spins and encounters the cylinder being tested, the incremental increase on the gauge becomes smaller. finally, after about 10 or 12 spins, it's maxed out.
For my diesel engine, I got numbers around the following:
first spin: 280 psi
second spin 380 psi
third spin 450 psi
twelfth spin 480 psi
These numbers were pretty consistent in all 6 cylinders.
So my question is this: what is the correct "compression reading" for the cylinder? I can't seem to find an answer to this question by doing web searches.
thanks
Dana