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Old 04-14-2009, 02:04 PM   #1
unclemat
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Default Built motor - drinks oil, blue smoke under boost - help!

Ok, so I got a built motor... works fine, except drinks oil at the rate of at least 1 qt / 400 miles. The motor has 1800 miles now, and it's been doing it since the beginning - well, at the very begining the consumption was perhaps slower (like 0.5-0.6 qts in first 300 miles) but I was breaking it in with little to no boost initially.

Observations:

1. Blue smoke clearly visible under boost - but no gobs of it - it's not visible in the rear view mirror. Had to follow my car in another car to see it. Faint blue smoke is visible also under light boost/acceleration.

2. No smoke under deceleration at all. No smoke on idle.

3. Compression is 150/141/150/145 psi and leakdown is 6/8/8/6%.

4. PCV valve is fine. To verify it's not crankcase venting issue I've been running with open PCV (venting to a ghetto catch can and then to atmosphere) - and no noticeable amount of oil collects in the "can".

5. Intercooler is dry, just thin film of oil inside the IC-TB hose (not even a pool of oil).

6. Turbo seems fine. I removed it and it's bone dry on the exhaust side. I removed even the compressor cover to see if there are sign of oil on the compressor side - not really. Ever so slight film of oil on the backplate.

7. Obviously, I checked everywhere several times for external leaks and there are none.

Any ideas? Why it's really only visible under boost? (which would indicate bad turbo) The exhaust is catted and I believe a cat can mask amount of visible smoke. Is it so?

Can it be that oil control rings are bad? Or perhaps the leakdown numbers aren't so great? My engine builder is telling me the leakdown numbers are fine. But then I had a stock motor with one ringland cracked that had 8% leakdown at that jug (2-3% on the others) and it was eating oil at a rate about 1 qt / 650-700.

Maybe a problem in the lower portion of the cylinder(s) bore? So it's not caught by compression/leakdown?

I'd like to find it's not an internal engine issue, i.e. that it is the turbo but it doesn't look like...

Thanks for any suggestions in advance.
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Last edited by unclemat; 04-14-2009 at 06:24 PM.
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Old 04-14-2009, 04:06 PM   #2
flycaster
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Your leakdown numbers are high for a freshly broken-in motor. Not terrible, but too high imo. The fact that the burn rate is getting worse, not better, is troubling. If I had to venture a wild guess, I'd say you have some cylinder glazing that took place during the first part of the ring seating process.

What kind of "built" lower end are we talking about here? Also, what P-SW clearance was used and what ring gaps were used?
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Old 04-14-2009, 04:20 PM   #3
unclemat
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This is a 2.5L bottom end with stock size CP pistons. Block was honed. .0032-0033" P-SW clearances (piston skirts coated). Ring gaps (top/2nd/oil): .18/.20/.12".

Honestly, I also would have preferred to see the leakdown numbers lower, but then I have no experience with built motors and was told they are very good for the mileage

I think the rate of consumption is stable now (however crazy high), it was just lower in the initial period, when I wasn't boosting it.

Basically at this point I debating whether I should try to swap the turbo, or pull the motor.

Last edited by unclemat; 04-14-2009 at 04:25 PM.
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Old 04-14-2009, 04:47 PM   #4
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How'd the plugs look when you did the comp/leakdown test? Can you narrow it down to one cylinder?
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Old 04-14-2009, 04:53 PM   #5
unclemat
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Quote:
Originally Posted by jays05 View Post
How'd the plugs look when you did the comp/leakdown test? Can you narrow it down to one cylinder?
Not really. They look pretty much teh same. When I pulled them first at like 1k miles, #2 plug seemed to have some oil on the threads. #4 plug seemed to look bit better than others. Now at 1.8k miles, when I did compression/leakdown again, all were dry and looked pretty much the same, just with carbon build up (somehwat less than at 1k miles, didn't take pics). Picture of plugs at ~1k miles:

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Old 04-14-2009, 05:01 PM   #6
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ever think or hear of valve seals going bad????? makes sense doesnt it? especially if you have steady and close compression and leakdown isnt off much.

Last edited by hybridpatient95; 04-14-2009 at 05:07 PM.
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Old 04-14-2009, 05:02 PM   #7
unclemat
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Quote:
Originally Posted by hybridpatient95 View Post
ever thing of valve seals going bad?????
Yeah, but I understand the symptoms is smoke under deceleration... especially after lifting the throttle.
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Old 04-14-2009, 06:00 PM   #8
hybridpatient95
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Generally, blue smoke during hard acceleration indicates faulty oil control rings. While blue smoke during deceleration and on startup after the engine has been off for a while indicates faulty valve guide sealing either from leaking seals or excess guide clearance
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Old 04-14-2009, 06:12 PM   #9
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my car did the same thing...turbo seal was gone in a big way you could see oil pouring out around the center section clamp. but in your case thats jus odd...
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Old 04-14-2009, 06:28 PM   #10
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Those plugs make it look like oil is getting into the combustion chamber. It it's not coming in the intake and it's not the turbo then it's got to be piston/rings or valves

Off subject but are those the right plugs for your heads? they look like they extend into the chamber more than I remember.
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Old 04-14-2009, 06:32 PM   #11
unclemat
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Quote:
Originally Posted by mick_the_ginge View Post
Those plugs make it look like oil is getting into the combustion chamber. It it's not coming in the intake and it's not the turbo then it's got to be piston/rings or valves
Figures as much... I am just trying to determine if the compressor can be shooting oil into the engine, without really leaving a significant trace of oil in the intake path (past turbo). Sort of an "oil mist"... Catching at straws, I guess. It really sucks to pull a new engine.

Quote:
Off subject but are those the right plugs for your heads? they look like they extend into the chamber more than I remember.
Correct plugs. It's an 04-06 STI engine.
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Old 04-14-2009, 06:54 PM   #12
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I have the plugs that were in my motor from break-in to 3k miles right here and they all look like your #4.
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Old 04-14-2009, 07:14 PM   #13
john 1badSTI
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if you do a wet vs dry comp/leakdown it will tell you if its the rings are not seated properly.the percentages will get smaller(seal get better) when you squirt a little oil in the cylinder before the test if the rings are not sealing properly.I agree with mick those plugs look like a minute amount of oil is getting into the chamber.
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Old 04-14-2009, 08:53 PM   #14
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How is the 2nd ring installed? per CP instructions: 2. If the ring is a taper hook groove style, the groove
always goes down. (Figure 4) CP ring installation instructions If the groove is installed facing up it will pull oil into the combustion chamber.
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Old 04-14-2009, 09:08 PM   #15
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it prolly has been said.

by most likely blow by rings not sized correctly or they were not set correctly, head do a leack down this will help you trouble shoot
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Old 04-14-2009, 09:19 PM   #16
unclemat
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Quote:
Originally Posted by methaddict View Post
How is the 2nd ring installed? per CP instructions: 2. If the ring is a taper hook groove style, the groove
always goes down. (Figure 4) CP ring installation instructions If the groove is installed facing up it will pull oil into the combustion chamber.
Don't know that, unfortunately, will have to check with the builder.
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Old 04-14-2009, 09:27 PM   #17
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How did u break it in? stock rings or CP?
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Old 04-14-2009, 09:33 PM   #18
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Quote:
Originally Posted by bertune View Post
How did u break it in? stock rings or CP?
CP rings.

Rather "easy" break-in - I didn't baby it, but I wasn't getting on it either. Varying rpms, lots of engine braking, etc. No boost to low boost (3-5 psi maybe) for first 300 miles (and 4k rpm max) then like max. 10 psi (and 4.5k-5k rpm max) for next 400 miles then 18 psi.

I made sure to load it up early observing rpm and boost limits. Short burst of throttle going uphill, etc.
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Old 04-14-2009, 09:38 PM   #19
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Was it running rich at start up
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Old 04-14-2009, 09:41 PM   #20
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Quote:
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Was it running rich at start up
No. Perfect AFR's right away. Car has solid and tested tune on it. Started right up. I am sure it's not a bore wash issue.
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Old 04-14-2009, 10:03 PM   #21
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I usually break in a little hard in the early stages of a new build to get the rings seated early out. I guess to each his own. I built a motor some time ago and had the same problem u are having ( didn't smoke), i drove it for about two years and even ran 10's with it, but it eventually it got to me, filling it with oil every minute, so i rebuilt it. I was running stock rings.
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