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Old 12-20-2012, 07:25 PM   #1
OC_Nooby
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Default Compression Test Results, Forged Internals. Thoughts?

Hey Guys,

So I decided to finally do a compression test.

Results as follows:

Cylinder 1 = 117
Cylinder 2 = 117
Cylinder 3 = 105
Cylinder 4 = 105

The motor was idled for a solid 20 minutes, oil temps where around 85°c and water temps where about 95°c. Took the measurements right away with open throttle.

Cylinder 2 and 4 where tested in the summer time when the car had about 3500 km's with the same results. Car currently has 8500km's.

Its a fully built shortblock:

CP 8:2:1 Forged Pistons
Manley Turbo Tuff I Beam Rods
Nitrated Crank
MAP H11 head Studs
New Gasket/Seal kit


I haven't done a leak down test but I will do one or try to do one tonight (have to fix the leak down tester, gauge is bad). I did some reading around and these numbers are way to low. Could the machine shop have done a horrible ring gaping job? They where recommended in the Ottawa Ontario area but I felt they did a bad job. I found metal shavings in the oil passage way and they used the wrong cam seals, I went on faith that everything else was fine (I cleaned the shavings and put the proper seals on). I told them to torque plate the block but I doubt that happened either (I even offered to buy some plates if they couldn't make anything). Anywho I have pictures of the shavings and I still have to talk to them (once I do the leak down).

I get about 70 kpa of vacuum which is good if not great.

I have to recheck my oil but I believe I'm consuming, Its hard to get a proper reading so its frustrating.

What do you guys think?
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Old 12-21-2012, 03:55 PM   #2
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Ever so lonely in here. Still need to fix my leak down tester
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Old 12-21-2012, 04:28 PM   #3
Dillinja666
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11% difference between the heads...hm me no likey.

Edit: ya just saw the miles, um yes looks like its time to do a leak down test and see whats up.
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Old 12-21-2012, 05:07 PM   #4
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How was the engine broken in? If it's consuming it may have not been broken in well.
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Old 12-21-2012, 08:03 PM   #5
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Quote:
Originally Posted by ckyguy68 View Post
How was the engine broken in? If it's consuming it may have not been broken in well.
Aggressively, lots of engine braking and boost.

I also got them to build the heads. Maybe they didn't do that properly. Who knows. Fixed my leak down so I'll get her warmed up and do the passenger side tonight.
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Old 12-21-2012, 08:30 PM   #6
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Quote:
Originally Posted by Dillinja666 View Post
11% difference between the heads...hm me no likey.

Edit: ya just saw the miles, um yes looks like its time to do a leak down test and see whats up.
Isn't the engine setup with 1&3 on the right and 2&4 on the left?

It kind of sucks to run into a problem like this because there could be one or more problems.

Best of luck!
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Old 12-21-2012, 09:16 PM   #7
FXTRunner
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Did you hold the gas pedal down while cranking the engine for the compression test?
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Old 12-21-2012, 09:45 PM   #8
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I'm in agreement with most of what's being said.... there are just soo many variables.

If you can't do a proper leak down.... fix this first.. then go into diagnostic mode.

Hows your coolant??? still clean?


Aslo aside from getting baseline numbers for your build what was the purpose of you doing a compression test?


You should also post this in the build motor subforum. If you haven't already.
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Old 12-21-2012, 10:53 PM   #9
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Quote:
Originally Posted by holyjoetart View Post
Isn't the engine setup with 1&3 on the right and 2&4 on the left?

It kind of sucks to run into a problem like this because there could be one or more problems.

Best of luck!
Cylinder 1 – passenger side towards the front of the car
Cylinder 2 – driver’s side towards the front of the car
Cylinder 3 – passenger side towards the firewall / passenger compartment
Cylinder 4 – driver’s side towards the firewall / passenger compartment

Quote:
Originally Posted by FXTRunner View Post
Did you hold the gas pedal down while cranking the engine for the compression test?
Yes

Quote:
Originally Posted by DHRDAN View Post
I'm in agreement with most of what's being said.... there are just soo many variables.

If you can't do a proper leak down.... fix this first.. then go into diagnostic mode.

Hows your coolant??? still clean?


Aslo aside from getting baseline numbers for your build what was the purpose of you doing a compression test?


You should also post this in the build motor subforum. If you haven't already.
Coolant isn't dirty. I did the compression test, one for oil consumption, 2 for the fact I couldn't iron out this weird hesitation from 2000rpm to 3000rpm. lastly for ****s and giggles. Mainly oil consumption.
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Old 12-21-2012, 11:02 PM   #10
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So I warmed up the car, and put my leak down tester in. First go I wasn't at TDC because air was coming out of the turbo inlet at 60psi. So I clearly was at the wrong stroke. So I cranked the crank pulley some more and found the compression stroke and TDC. Put in 100psi and found out 2 things. One my ebay leak down tester is garbage because 100 psi showed on both gauges. But the interesting thing I did find out was I had a small amount of air coming from the turbo inlet. If I opened the oil filler cap the air would come out of the there. If I capped it back up I could hear air coming again from the turbo inlet. Not by much but it was there. Slight hiss.

That was on cylinder 3 (passenger rear). I'm pretty sure I was at TDC cause I decided to be smart and check to see if I may have been slightly off and ever so slightly cranked the crank pulley with the wrench and lets just say my hand took a beating. Feels awesome...

For reference. I put a long metal file to determine tdc. First time I was on the wrong stroke (exhaust stroke) second time I was on the compression stroke, hence the hurt hand.

Unless I did it wrong. First timer.
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Old 12-22-2012, 12:09 AM   #11
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Have you checked timing?

Your always going to get a little bit of air going around the rings, but you shouldn't get any air past your valves if they are closed.
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Old 12-22-2012, 12:30 AM   #12
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Originally Posted by holyjoetart View Post
Have you checked timing?

Your always going to get a little bit of air going around the rings, but you shouldn't get any air past your valves if they are closed.
Yah, I understand some air would go through the rings but not the valves.

You know what. I'm a tool. The air could have been coming out from the PCV system or crank vent. I have a catch can setup for the PCV and crank vent. So yah, I'm dumb, the air I herd could have been those. I'll build my own leak down and try again. Though I could fell the air from the filler cap. I'm guessing it's a pretty healthy leak.

I'll make my own leak down and try again.

Last edited by OC_Nooby; 12-22-2012 at 12:47 AM.
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Old 12-22-2012, 12:45 AM   #13
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I was going to edit my post and mention pcv valves. You could squirt a little bit of oil in the cylinder to coat the rings so the air won't bypass them,to check how the valves seal.

I think you know, as well as many of the readers, that your problem is pointing to the clearance between the rings and the cylinder wall. You still have to troubleshoot and verify the cause of the problem, but be prepared to do another teardown.

Last edited by holyjoetart; 12-22-2012 at 12:53 AM.
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Old 12-22-2012, 12:49 AM   #14
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Quote:
Originally Posted by holyjoetart View Post
I was going to edit my post and mention pcv valves. You could squirt a little bit of oil in the cylinder to coat the rings so the air won't bypass them,to check how the valves seal.
If I put some oil in the cylinder and compression rises would that tell the rings aren't gapped very well?

I'll build a leak down tester and have that ready next time I attemp this.
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Old 12-22-2012, 01:47 AM   #15
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Yah, I feel it will be a teardown. If they torque plated the motor and the cylinders are round I don't mind buying new rings and have them reseat them. They said they would warranty the block if they screwed up when I initially went with them.

But alas, leak down to see how bad it is. Go from there. Sometime next week sadly.
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Old 12-22-2012, 09:52 AM   #16
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If in any way you think there may be issues with the block, especially if you're thinking they may have to warranty their work, be sure and document everything. It may, or may not, do much good with them but will only help if it gets legal.

Oil in the cylinder won't necessarily tell if the rings are gaped correctly but will do a good job of sealing around the piston/rings/cylinder wall which can help point you in the right direction.
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Old 12-22-2012, 12:59 PM   #17
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Quote:
Originally Posted by k mier View Post
If in any way you think there may be issues with the block, especially if you're thinking they may have to warranty their work, be sure and document everything. It may, or may not, do much good with them but will only help if it gets legal.

Oil in the cylinder won't necessarily tell if the rings are gaped correctly but will do a good job of sealing around the piston/rings/cylinder wall which can help point you in the right direction.
If they won't warranty the work its not going to get legal. I would have to cut my loses and find another machine shop. Its Canada after all...
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Old 12-28-2012, 07:24 PM   #18
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Alright,

Well I did a leak down test on cylinder 1 and 3:

Cylinder 1: 5%
Cylinder 3: 12%

Compression test:

Cylinder 1: 117
Cylinder 3: 105

I haven't done the other side but yah, this doesn't look good.
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Old 12-29-2012, 12:13 AM   #19
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Quote:
Originally Posted by OC_Nooby View Post
Alright,

Well I did a leak down test on cylinder 1 and 3:

Cylinder 1: 5%
Cylinder 3: 12%

Compression test:

Cylinder 1: 117
Cylinder 3: 105

I haven't done the other side but yah, this doesn't look good.
Personally, the fact that there is such a discrepancy between the cyl. 1/3, that' not a good sign. Heck, my eclipse GSX has 130k miles, and the compression test had exactly 155 on all four cylinders. A motor that fresh with numbers like that means that there's probably an issue there. Good luck man, seeing stuff like this makes me cringe considering I just put a built block in my STi.
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Old 12-29-2012, 01:50 AM   #20
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Originally Posted by ByeBye4g63t View Post
Personally, the fact that there is such a discrepancy between the cyl. 1/3, that' not a good sign. Heck, my eclipse GSX has 130k miles, and the compression test had exactly 155 on all four cylinders. A motor that fresh with numbers like that means that there's probably an issue there. Good luck man, seeing stuff like this makes me cringe considering I just put a built block in my STi.
I wouldn't worry about your block. I just picked the wrong machine shop. I feel if it was a tuning issue I'd have low compression on a cylinder. Having them low on all 4 is just weird. I honestly believe they gaped the rings incorrectly, though I don't know much about building blocks. I might just buy a stock sb and give up. I'll see what the machine shop says on Monday.
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Old 12-29-2012, 08:31 AM   #21
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It's weird, it's almost like the back half of the motor went. Wonder what would do that.... Since the cylinders effected don't share a cam, it'd be hard to say it has jumped time since the front cylinders seem to be fine.
The only thing I can think of is that the heads weren't torqued in the right order and it is a bad seal at the back half of the head since most likely the same procedure was carried out on both sides. That is just a theory though.
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Old 12-29-2012, 01:03 PM   #22
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I'll be doing the other cylinders tonight. It should be interesting to see the results.

Last edited by OC_Nooby; 12-29-2012 at 01:24 PM.
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