compression test on rebuild ca

[ca18det240hatch]

well i compression tested my ca18...not too happy. it pulls great, theres no blowby....but still i got 130, 130, 100, 130..... what could i have ****ed up in my build to cause that? and ideas? Im 1mm overbore and 1.2mm cometic head gasket...

[page02wrx]

Are you timed right? One tooth may or may not cause something like that

[AWDB12wagon]

how long has it been since you rebuilt it? the rings may not have seated yet.

[ca18det240hatch]

Its been about 1000km

i dont think the timing is out, i was pretty meticulous about that....did it on the stand with it right in front of me, then spun it a buncha times to make sure it didnt move from the marks

[page02wrx]

Its been about 1000km

i dont think the timing is out, i was pretty meticulous about that....did it on the stand with it right in front of me, then spun it a buncha times to make sure it didnt move from the marks

The #'s don't make a whole lot of sense... unless like AWDB12 said, the rings haven't seated yet....

If your friend has a compression tester, try using his to see if you match the #'s.

[AWDB12wagon]

did you put your ring gaps 90 degrees out?

[r34 gtr]

was the head/block mating surface milled true? it wont seal properly with that cometic HG otherwise. that third cylinder is what bothers me. nothing wrong with some slightly low compression as long as you know the engine is in flawless condition and the numbers are all similar.

[boost_boy]

well i compression tested my ca18...not too happy. it pulls great, theres no blowby....but still i got 130, 130, 100, 130..... what could i have ****ed up in my build to cause that? and ideas? Im 1mm overbore and 1.2mm cometic head gasket...

Hmmm, not good! First question, did you install your rings correctly? If you didn't and your rings are upside down, this will be one of your problems. Did you check the bore's diameter before installing new rings? If you bores were worn, could be another problem. Did you check ring end gap with proper feeler gauge? If you didn't, could also be your problem. And lastly, did you properly torque the head in the stages required when you using a composite gasket? If you didn't that could be your problem. I seriously doubt it's because your rings are not seated. Even with your rings not fully seated, you should have a much more even and higher compression than you posted. I suggest paying close attention to the things I mentioned above.

Dee

[ca18det240hatch]

head was milled, was told block was fine, the bores were brand new, bored them out 1mm over, i clearanced all the rings, with a feeler gauge to the specs total seal provided...i had to use a file tho.....dunno, maybe i read the number wrong and over clearanced. teh rings were set properly, but my ring compressor is a piece of **** and prolly moved them. The rings were installed right side up, total seal provides a dot on the side that goes up. Im very much disturbed by the numbers. It doesnt burn any oil, it pulls VERY hard, idles great....so i guess im just gonna drive the **** outa it till the end of the summer and throw new rings in and try again, with a better ring compressor. thats the only thing i can think of, the rings moved. My oil did get pretty dirty from the first 1000km.......so im thinking theres a small amount of blowby....nothing enough to blow my dipstick out or anything, even at 10 psi.

hrrmmmmm, guess its time to yank it again come winter. still think i did pretty good for my first build ever....it runs...and i got the bottom end right

it still does great for oil pressure, 11 psi at idle, 70 psi at 3000 rpm, which is 10 psi higher than FSM states.

[boost_boy]

Alright, you covered the more sensitive stuff, so let's look at those total seal rings. Don't have too much experience with total seal rings, so if you did everything else I mentioned, I'm stumped as to why your #s are so low. Are you sure the head is torqued correctly?

Dee

[ca18det240hatch]

1st step. 22 ft/lb, 2nd step, 76 ft/lb

loosen all,

1st tep, 22 ft/lb, 2nd step, 76 ft/lb

all in order of what the fsm told me

[r34 gtr]

im using total seal rings and im seeing ~165psi across the board. i did NOT check the bore diameter. i did NOT check the end gap, and i did NOT bother aligning them to 90 degrees (though i believe they ended up that way). the dot on top does kinda idiot proof them.

did you do the compression test hot or cold? maybe your tester sucks.

[ca18det240hatch]

maybe ill try a different tester.

i checked the compression 10 minuts after i shut it off.

i clearanced the rings, maybe too much.

youre using total seal in your ca18?

[r34 gtr]

hell yeah, and i will next time i change them too.

[ca18det240hatch]

i prolly clearanced them wrong or something.

that 3rd cylinder, i dont know why its lower than the rest, but im sure ill find out come winter time.

[davidricardo86]

Could it be maybe a valve is not sealing right?

Or a bent valve?

Try re-torquing the head studs if you can.

Maybe the headgasket didnt seal right? You didnt have the block decked right?

Try using a different tester. Also why not use a little bit of oil to see the difference between wet/dry test.

Check that the spark plug is torqued correctly. It could be loose you never know.

[r34 gtr]

im not sure how the plugs could enter into it as its a compression test...

but do some more tests and see whats wrong with cyl. #3

[ca18det240hatch]

wouldnt i be able to hear the compression leak if my headgasket didnt seal properly?

[r34 gtr]

not necessarily. check the oil, is there coolant in it? is it brown? how about the coolant? is it brown? oily?

[ca18det240hatch]

no oil in the coolant or vice versa

hrrmmm

On another note....spark plugs....i need to get the correct heat range i think

do you know the number for ngk iridium for ca18det? or any good plug number?

[ca18det240hatch]

never mind, got my plugs

what is the boost cut on stock ca18det computer?

i find it brick walls at 12 psi on my car....

[float_6969]

It's different for different turbo's, but 12psi sounds about right. It's actually based on volume of air, so a bigger turbo will cut at a lower boost pressure.