Compression test #s?

[Wiggles422]

I'm going to borrow a compression tester from a friend before I decide to up the boost. I figured it would be a good piece of information to have so I can check every so often just to be on the safe side. Anyways I'm sure someone else has done this... what numbers are to be expected? I'm guessing 190ish (shrug)

[wicked]

don't know the numbers off hand,but just make sure they are about the same for each cylinder

[t3ase]

subscribe. Discreet told me a while back, ask him.

[Wiggles422]

Bizzump... I PMed discreet, but he hasn't been on since 8-20 so I don't expect an immediate answer.

[dominoy2k1]

it should be around 190-200. from i remember when maurice did his first test it came out around 185. but he had been boostin high for a while.

[Wiggles422]

(thumb) thanks

[MSP Chris]

I'll check mine tommorow, I'm guessing something bad. lol

[Emode]

can someone tell me whether or not the proper procedure is to do the compression test with the throttle open or closed. I thought it was supposed to be open but my friend said no, and we did it his way. I ended up getting between 135-138 on all four. Ive been upped on boost for awhile and this was done awhile back, cars still fast and runs well. Im thinking it had something to do with that.

[dominoy2k1]

i dont mess with the throttle, also did you remove the fuel inj fuse? the manual said to do it.

[BlkZoomZoom]

throttle should be open. Those numbers are slightly low, still within specs. Could just mean you didnt get a "good" motor like me. lol

[DSMConvert]

throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...

[azian6er]

throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...

good info :)

[mspeedpro]

we should all check our #s -=/

[daKiNeP5]

I checked mine last week and I came out with 173, 163, 170, 173

[Wiggles422]

I went to Autozone to rent a compression tester and they didn't rent them. So I went to PepBoys, they didnt have one in stock. Does anyone know of any other places that rents tools? (for free) I think I might just order one online, they're fairly cheap.

[wicked]

autozone doesn't useally rent tools what they do is sell you the tool and when your done you return it for a refund.

[turbo speedy]

my compression was 185 in 1st and 2nd piston 3rd and 4th was 190 and i have had my boost for about 4 months

[Kooldino]

throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...
Never heard that, where did you hear this?

Anyway, my compression #s on my stock motor were 175ish, but then when I did them again with the injector fuse pulled, they were 140ish. Ditto for my new motor.

[Kooldino]

I checked mine last week and I came out with 173, 163, 170, 173
Did you pull your injector fuse?

[MSP Chris]

lol u can rent them

[Wiggles422]

autozone doesn't useally rent tools what they do is sell you the tool and when your done you return it for a refund.

they rent tools, just not the compression tester. all they ask for is a deposit.

[DSMConvert]

kooldino which part are you refering too? the basic compression test I learned from my ASE class, the capful of oil I picked up from a couple of engine gurus that helped me out when I blew a ring in my dsm motor...between my friends and I we've done it about 7 times now and its been right on the money everytime, one of the most useful tricks I've learned in the shop...

[Wiggles422]

noob question... if you put oil down thru the spark plug hole, how do you get it out? or is it not enough to worry about and it gets out once the engine is ran?

[DSMConvert]

it'll burn right out(little puff of smoke out the exhaust when you turn it over and thats it) but its very important you only use a capful, otherwise you'll foul your sparkplugs out in a heart beat.

[PaulMP3]

i get around 175-185 on all 4.

[DSMConvert]

just looked at my log book for my 95 mx6 fsde motor both before and after the turbo kit build...before it was 183, 185, 182, 189...3 wks after turbo @ 5psi, 184, 182, 186, 186....so I'd wager to say you should be in the mid 180s...

[t3ase]

Just to revive an old thread.. Just did a test with results of:
1. 180 2. 181 3. 176 4. 183 ~45k, 14psi, mods below.
(2thumbs)

Tried the blowby "test" as suggested by DSM with some different and varying results:
1. 184 2. 209 3. 200 4. 197
:eek:

[Matthew]

i wouldnt worry about the bottom numbers, but one seems about 5 low or so.

[jeffmsp]

hmmm, i got 180 in all cylinders, but i did not remove that fuse, could that be causing incorrect numbers for me?

[Matthew]

you will get different compressions different times, diff cars, diff altitudes etc. so long as they are within (from what i understand) 20 of each other, and not TOO low, youre good.

[wicked]

mine sucks
150-152-150-151

that is done correctly,fuel dissabled,and throttle open.

I would have done a running compresion test,but didn't have time.
gonna due a cylinder leakdown tommarrow