I did a comression test today at work and this is what i got #1-120 #2-120 #3-115 #4-120 this seems kinda low to me. it was my first time doing a compression test so i dont know if i did it wrong or what. i let it crank 3 times on each one.

This was on a b18a1

what do you think?

 

You need to crank it at least 6 times with the throttle wide open. The differences are not much to be worry of anything.

 

Those #'s seem pretty low.

 

Get engine up to operating temp (let cooling fan cycle one time).You need to pull the 2p connector to the distro. Puht the trhottle in completely (floor it) and crank the engine over. Have someone watch the gauge when it peaks out stop cranking. Refer to the service manual for the service limits. Thoes #s are a bit low BTW. Maybe you did it wrong.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 12secB18acivic &raquo;</TD></TR><TR><TD CLASS="quote">Those #'s seem pretty low.</TD></TR></TABLE>

Yeah, doesn't seem like test was performed properly. I usually just pull the ecu fuse and crank wot 5-6 times with someone watching the guage. Test each cylinder at least twice. Pulling the ecu fuse also kills fuel that sometimes throws off compression test results.

 

i did pull the dis. plug and i ding not hold down the gas to the floor but if i would crank it more than 3 times the needle would still go up so i did the test wrong?

 

With throttle wide open you get more air into the cylinder before the intake valves close and compression starts. More air under pressure results in higher comp #'s.

 

also, the person who is holding the gauge needs to hold it straight up and not laying on the valve cover or anything....

 

hey man those numbers are low
i have a b18b1 and all of my numbers were as follows
1-205
2-197
3-198
4-200

yours should be somewhere around 160-190

 

i think i did the test wrong. im going to do it again today

 

When you redo the test, If you are using a cheaper compression guage, you may want to use a little motor oil on the threads. I had a cheap one once and the threads were not a snug nice fit aloowing air to escape. Also if you get the bad numbers again, I like to drop a couple of cc's of oil into the sparkplug hole, let it sit for 30 seconds and try again. Older motors really rely on oil on the cylinder walls (that is why synthetic is not the best for high milage units. Good luck.

 

Adding some motor oil into the cylinders is just for diagnosing purposes. It will help the rings seal better for a higher compression reading. But your readings are so far ok, what you need to do is crank it at least 6 times, not 3. After you do the test again and am not satisfiy with the readings, then do a leak down test and it will tell you where you're having trouble sealing.
Oh, one more thing, Make sure your battery close to being full charge, because A low battery ouput cannot turn the crank fast enough to get high readings. That's why I said to focus on the difference from high-low and not the final reading.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sleepN &raquo;</TD></TR><TR><TD CLASS="quote">That's why I said to focus on the difference from high-low and not the final reading. </TD></TR></TABLE>

Yup, different factors can affect the psi, just check for consistancy, my ZC got 150 across the board but its a strong little motor, it gets 10.4's in the 1/8 with a 2.4 60 and in the fat *** 4dr ex.

 

Be sure to kill the fuel injectors because they will wash down the cylinders and you will get lower readings.

 

if you do it again and you get low #s put a little bit of oil in the cylinder and try it. If your numbers jump up then most likely your rings are about gone. Those #s do seem aweful low though my b16 gets straight 220s