I did a compression test, and then again while adding a drop or 2 of oil before testing, 2 cylinders seemeed same, one raised by ~5psi, the other one dropped by ~5psi..

i have 2 questions:

1. i read about adding oil during compression test, but what am i to make of it if its goes up or down after adding oil?

2. another question, for some reason gauge would show 200-205psi right after i stop and then drop to 190-195psi per cylinder, is that normal?

 

The problem with compression tests is that they are not consistent or repeatable. You can test the same cylinder all day and get different results each time.

What I do is try to be consistent with the number of cranks. And I do each cylinder 2 or 3 times, write em down, and use the middle number to compare.

As for your gauge bleeding pressure it sounds like its doing just that. Probably caused by an air leak somewhere. Either not a tight seal or an old/cheap gauge.

 

i did each cylinder 2-3 times and 2-3 times with oil added, same amount of cranks per test, results were pretty consistent.. what i want to understand why would pressure drops after adding oil and in one of my cylinders possible went down 5psi, and.. what does it mean if it stays the same

as far as gauge, its cheap, so i guess thats what it is..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">i did each cylinder 2-3 times and 2-3 times with oil added, same amount of cranks per test, results were pretty consistent.. what i want to understand why would pressure drops after adding oil and in one of my cylinders possible went down 5psi, and.. what does it mean if it stays the same

as far as gauge, its cheap, so i guess thats what it is..</TD></TR></TABLE>


does anybody knows what it means when pressure goes up or down after adding oil?

 

Why would you add oil to the cylinder in a compression test if you dont know why you are adding it?

If the pressure goes up after adding oil it means the oil is plugging up leaks around the piston rings. All rings are going to leak some pressure but if adding oil makes a significant difference in the compression test then you have bad rings.

If the pressure goes down from adding oil, it means something is wrong with your test. It shouldnt go down. If the rings arent leaking then adding oil will produce the same results as no oil.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">Why would you add oil to the cylinder in a compression test if you dont know why you are adding it?

If the pressure goes up after adding oil it means the oil is plugging up leaks around the piston rings. All rings are going to leak some pressure but if adding oil makes a significant difference in the compression test then you have bad rings.

If the pressure goes down from adding oil, it means something is wrong with your test. It shouldnt go down. If the rings arent leaking then adding oil will produce the same results as no oil.</TD></TR></TABLE>

thanks for explainin .. i guess 5psi diference isn't to worry about

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">

thanks for explainin .. i guess 5psi diference isn't to worry about</TD></TR></TABLE>

if adding oil only increasses the cranking compression 5psi then there is nothing wrong.....