D16SiHatch

I'm only placing this here cause i figure i'll get better answers than in the crx/civic forum, and my main concern is whether or not these numbers would be acceptable to throw some boost at.

Ok so my only concern with the testing is the engine was not at operating temp. i wanted to warm it up more but my friend said it would be alright. i guess you guys can tell me if he's right about that or not. it was warm because it was running like 2 hours or so previous, but it certainly wasn't hot enough to even register the slightest on the temp gauge. regardless he said it'd be fine.. you tell me.

ok so the readings.

cyl 1: 176 leakdown: 35%
cyl 2: 175 leakdown: 30%
cyl 3: 182 leakdown: 35%
cyl 4: 178 leakdown: 30%

On alldata it said anything from 135 psi to 199 psi was considered normal, with maximum variance between cylinders of 28 psi.

Now from what i've read anything over 20% is supposed to require a major rebuild? which certainly concerns me. however the engine runs really well and doesn't burn oil *knocks on wood*. also what i found interesting is on the gauge itself anything less than 40% was in the green and considered low. 40-70 ish was moderate, 70+ was major leakage. or maybe he didn't do the test right? so far as i could tell i think he was doing it right, but i mean i dont have much experience with operating a leakdown tester.

So based on that would you think its remotely safe to even consider boosting, and does anyone feel results may be skewed at all due to the low engine temp during testing? also from what i was reading in the ls-t turbo b18a/b thread there were some people who had less impressive results and still were running some boost just fine. i'd appreciate anyones insight on this.

ninja edit: wow. after reading through the alldata specs it just occured to me we weren't even holding the tb wide open while doing the compression test :/

Alfa Turbo

Retest using proper procedures. If your leakdown figures are correct... oh-noes...

blaze the chemi

Your compression looks fine. Your leakdown results suck, but this could be due to the fact you didn't do the procedure 100%. I have found little variance between WOT and no throttle compression results. Not sure about leakdown though. Redo the test with WOT.

Also two hours of operation before testing is a sure bet your engine was at operating temperature.

irishflame27

with that much leakage, you have to check and see where the leakage is coming from.
if you hear it coming from:

the exhaust= exhaust valve
the throttle body= intake valve
take off radiator cap, if you see bubbles or moving coolant= headgasket
pull dipstick, if you hear air or can feel air= worn piston rings

make sure engine is warm while doing both the compression and leakdown tests

rmcdaniels

Those leakdown numbers are not good. It could be procedural though; I'd redo the leakdown test using the proper procedure and a different tester.

jewjew bean

I had a 99 ls motor with 46k that sat for 2yrs. I was selling it so the buyer wanted to see the leakdown. In the 3cyl I checked, it had 0% leakdown in those cyl. Motor doesn't have to be warm to do a leakdown and it seems like your motor is well wornn

Leakdown # don't mean **** if you don't know where the leak is coming from. That's the whole point of the test really

Alfa Turbo

On further thought... with those leakdown numbers being so high but consistent I wonder if they did not rotate the engine to TDC for each cyclinder and the valves were open a little on each pot. Would be funny and explain a lot at the same time.

jewjew bean

sry but that doesn't even make sense. you set the piston at tdc on the compression sroke. no other way to do it

Alfa Turbo

If the engine was NOT at TDC he could get these results... that is how it makes sense.

rmcdaniels

No, if the motor was not at TDC then it would have spun to BDC when it was pressurized. That's very noticeable. Additionally if the valves were open at all the leakdown should have been much higher.

D16SiHatch

see from what i'm reading about these 2 gauge testers is you're supposed to keep about 100 psi on the standard pressure inlet gauge, meaning 100 psi is entering the cylinder. and then the other guage registers how much of that is escaping. makes it easy to calculate percentage lost when your pressurizing the cylinder with exactly 100 psi. now the thing is i know when i was reading the inlet pressure gauge while he did this, it only registered like 23 psi or thereabouts. do you think this could cause the readings i was getting?

without bein a dick i'm going to try and convince him to retest it but i dunno if he will. i guess i might just take it somewhere else to have it tested. not sure where a good place would be though.

if anyone is curious this is the exact tester he was using



thought this was kind of interesting

"Don't be shocked if you see leakage from an otherwise good-running street engine around 20 percent. You could do an excellent rebuild and still not pick up appreciable power even if the leakage was substantially reduced."

quoted from here
http://www.carcraft.com/techarticles...er/index1.html

jewjew bean

it could be but then I have to ask how did you get your numbers?

ie. for cyl 1: 176 leakdown: 35%
did the second gauge read 65psi?

cyl 2: 175 leakdown: 30%
did the second gauge read 70psi?

it doesn't make sense to do a leakdown with 23psi line pressure. If his guage was reading that, I have a feeling that it was broken and he had his regulator set at approx 100psi

EDIT: there's no way to get have more pressure in the cyl than what is in the line so his gauge must have been broken

D16SiHatch

well see if you look at the second gauge its not a simple 0-100 psi gauge. when you start the test, the needle on the second gauge is all the way to the right in that little yellow section just below the green. as you find tdc the needle moves upwards towards the green, and so on. it doesn't have psi designations on the second gauge just percentages. so if its sittin in the green low section which indicates 30%, its the same as reading 70 psi. or atleast thats how i understand it. thats of course assuming you actually had 100 psi going into the cylinder, which i'm thinking there was not. he was dickin around with the regulator a lot too if i recal..

so basically i think we can agree the 2nd gauge saying 30% leakage is the same as a 0-100psi gauge reading 70 psi. i mean how else does it just randomly decide on a percentage lol. and i would believe the numbers i got were accurate if i knew 100 psi was getting into the cylinder. so like you said this leads me to believe he screwed it up somehow, or his inlet pressure gauge is malfunctioning. in which case i have no idea how much pressure was actually in the cylinder. because if 23 psi is going in.. and 70 is being maintained, well then i have a miraculous engine that can pull off a -47% leakdown, and hold more air than was ever introduced in the first place lol.

Alfa Turbo

Not if it was in gear tough guy!

rmcdaniels

If you fill the other cylinders with concrete, that it would stop it from spinning too.

Honda Bull

Leakdown numbers look quite high. But do the test and get 100 psi in the cylinders. There is normally only a slight variance when doing the compression test at WOT. Those numbers look decent depending on the state of the engine and its compression ratio (not sure what it was, probably missed it).

lol. I did a leakdown test for a friend who had just done it but wanted a second opinion since they had pretty high numbers (10-25%). I went over, did it, and they noticed I didn't need to hold the crank pulley to keep it from turning. They were stunned. They had someone else hold the crank pulley to keep it from rotating while doing the test. I told them they were doing it wrong. lol

EDIT: I used probably the exact same tester for this guy: i.e. one that reads in percentage rather than psi. But I definitely prefer the psi ones. I like knowing actual numbers and calculating the percentage myself.

rmcdaniels

Yeah, I've never needed to hold the motor in place. Just make sure it is at the top and it doesn't move.


To the OP, a leakdown tester is not very expensive, I got mine from Summit for $70. It only takes a small compressor to run a leakdown test. It beats having someone else do it for you.

Hybrid96EK

0% leakdown is a crock. That would mean there was absolutely no air escaping from the cylinders which is impossible. You will ALWAYS have SOME leakdown. I've never personally seen anything below about 5%.

jewjew bean

I wasn't a crock, BIOTCH!!! haha jk

I'm not saying absolutley no air was escaping, but IF there was, it was so little, it didn't even register on the gauge. This was on a MINT ls motor that I owned since 12 miles. It was babied.

Believe it or not, it's the truth!!!

jewjew bean

That second gauge is just a 0-100psi guage in polish. These leakdown testers are cheap and the gauges frequently break. That's what probalby happened to his.

If the second gauge was passed the green, that means there was 100psi line pressure. I think he did the test fine and if he was off it was only by a few pounds.

Boner_Ben

I must have a freak motor then!!