Hello fellow H-T members, i tried find this in the search area but could find nothing , but anyways i have heard several ways to do a proper compression test on a motor, how i have tried a compression test was at operating temp, take all the pugs out and put oil down the spark plug tubs and remove the fuse under the hood so no fuel gets sprayed into the motor, and at WOT crank like 6-7 times and then move on the next cylinder, i have also heard not to put oil down the spark plugs because if you have no compression the oil will make that cylinder have compression. now what is the proper way to do a compression test is it ??

A - Put oil down the spark plug tubs so you dont mess up the rings, removed the fuse under the hood so i fuel is getting sprayed, and at operating temp at WOT crank 6-7 times and move on to the next cylinder ?

B - Dont put oil down the spark plug tubs and at operating temp and removed the fuse under the hood so i fuel is getting sprayed, at WOT crank like 6-7 times and move on to the next cylinder ??

Thank you


Modified by 94DCTeg at 10:26 AM 4/21/2008


Modified by 94DCTeg at 10:30 AM 4/21/2008

 

Well your correct about the adding oil possibly skewing your results.. When you add oil to the cylinder thats called a wet compression test.. without oil is a dry compression test.. I would suggest you start with a dry compression test

Also to make sure you dont screw your car up like i did unplug your distributor, and cut off your fuel pump so your not spraying gas while your trying to do the test..

but you have the right basic idea about performing the test.. crank at WOT.. when i did mine though i kept cranking untill the psi maxed out which may have been a few cranks beyind 6-7

 

i did a wet and dry compression test, and the wet compression test came alot closer to the correct numbers, i got 200 accross the boards with a B18B, doing a wet compression test, and with the dry compression test, #1 cylinder was 195, cylinder #2 190, cylinder #3 178, and cylinder #4 was 200

Thanks

 

i always do about 10 cranks, dry all the way....203-213 on a b18b w/ 127,xxx

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94DCTeg &raquo;</TD></TR><TR><TD CLASS="quote">i did a wet and dry compression test, and the wet compression test came alot closer to the correct numbers, i got 200 accross the boards with a B18B, doing a wet compression test, and with the dry compression test, #1 cylinder was 195, cylinder #2 190, cylinder #3 178, and cylinder #4 was 200

Thanks </TD></TR></TABLE>

yeah thats because the oil will help seal the piston rings druing a wet compression test giving you higher numbers

my B18c with about 105,xxx was 205 to 215 across the board

I dont know if your having any problems but that cylinder 3 may be a problem.. I cant tell you off the top of my head but i think your not supposed to have more than 15 psi difference from the cylinders next to it

 

The "wet" test is done when you find one or more cylinders down on compression, if the #'s come up after adding oil, the problem is your rings, if not, valve seals or headgasket.

 

Hi i just ran a compression test is this normal ?


Wet Hot 2 squints of oil

Dry Hot
I