Compression Test And Ambient Temps
#1
Registered User
Thread Starter
Compression Test And Ambient Temps
Does the ambient temperature affect the numbers you get with a compression tester? I have a Craftsman compression test kit, and I've noticed that over the past 3 times that I've done the compression test my numbers have dropped. I'm not sure if I should be concerned or not. The thing is, even though the numbers have always dropped, they drop consistently. Cylinders 1, 3, and 4 always read about the same and cylinder 2 is always about 2-3% higher than the other 3.
The thing is, the first time I did the comp. test, ambient temps were probably in the 40s. I blew 240-250psi. The second time I did the test, ambient temps were in the mid- to upper-60s and I blew 230-235psi. This last time, ambient temps were in the low 90s and I blew 210-220psi.
Should I be worried? Or is there some physics at work here that I'm not aware of?
The thing is, the first time I did the comp. test, ambient temps were probably in the 40s. I blew 240-250psi. The second time I did the test, ambient temps were in the mid- to upper-60s and I blew 230-235psi. This last time, ambient temps were in the low 90s and I blew 210-220psi.
Should I be worried? Or is there some physics at work here that I'm not aware of?
#3
Registered User
Originally Posted by mxt_77,Jul 19 2004, 08:42 PM
Does the ambient temperature affect the numbers you get with a compression tester? I have a Craftsman compression test kit, and I've noticed that over the past 3 times that I've done the compression test my numbers have dropped. I'm not sure if I should be concerned or not. The thing is, even though the numbers have always dropped, they drop consistently. Cylinders 1, 3, and 4 always read about the same and cylinder 2 is always about 2-3% higher than the other 3.
The thing is, the first time I did the comp. test, ambient temps were probably in the 40s. I blew 240-250psi. The second time I did the test, ambient temps were in the mid- to upper-60s and I blew 230-235psi. This last time, ambient temps were in the low 90s and I blew 210-220psi.
Should I be worried? Or is there some physics at work here that I'm not aware of?
The thing is, the first time I did the comp. test, ambient temps were probably in the 40s. I blew 240-250psi. The second time I did the test, ambient temps were in the mid- to upper-60s and I blew 230-235psi. This last time, ambient temps were in the low 90s and I blew 210-220psi.
Should I be worried? Or is there some physics at work here that I'm not aware of?
1. Hook the car up to a charger for consistent cranks
2. WOT
3. And make sure the engine is at normal operating temperature
I guess maybe with colder ambient temperatures, the air is denser and you may pack a little more cylinder pressure, i've done mine in cold and warm weather and i've gotten almost the same results.
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