compression test result on AAN.

[popdemonic]

Recently,I have some issue about my excessive oil coming out the PCV system.

Today i just done the compression test.As following the procedure,Remove

5 spark plugs,open 100% throttle while cranking,engine temp reached operating

degree.I got 140 155 150 155 165Psi(1-5).It has 240,000kms on clock.Is this supposed

to be too low number on the compression result?the AAN motor is bone stock internals.

I remember i had another AAN with All 5 cylinders got 115-120Psi but still never had

excessive oil vapor/fumes issue.I also replacedthe regulating valve,034billet check

valve under intake manifold.First,i run the Provent 200 oil catch tank and plumb it

back to MAF hose .Unfortunately,the Provent 200 couldn't cure the issue.the PCV still

blow a fair amount of oil inside the intake tract.So i decided to block it off and run it

with open system.I need to remove the pressure relief valve under the Provent 200's

cap ,block off the output port.The reason i need to remove the pressure relief cap

since i found that on the idle,it creates a big vacuum on the PCV system.i even

couldn't open the motor oil cap.the big vacuum hold my motor cap in place tightly.

I'm not going to rebuild motor in the a very soon since the major issue is oil inside

the intake tract is annoying me.I need to remove the relief under the cap and let the

pressure releases through out the cap and the oil dips will be back to the sump via

the small nipple on the bottom .

[prj]

First of all, please please please write with proper paragraphs.
This text is very hard to read.

I got 140 155 150 155 165Psi(1-5).It has 240,000kms on clock.Is this supposed to be too low number on the compression result?the AAN motor is bone stock internals.

Yes, this is quite low.

I also replacedthe regulating valve,034billet check valve under intake manifold.

Worst mistake you have made. Remove that valve and just blank it off. It's not needed.
I have personal experience of this 034 valve going bad (stuck open) after 1 use, the turbo boosting the crank case and engine failure.

Catch tank is not needed on a fresh engine.
I have multiple rebuilt engines running over 500hp and their catch tanks are almost completely dry. The only contents are some condensation when drained.

If your engine is pushing oil, most of the time it means your rings are shot.
Time to take the head/sump off...

[AndyP]

I think your compression numbers are OK, factory spec is 130-188psi with a maximum difference between cylinders of 43.5psi, personally I'd like to see them much closer than that. Your figures of 115-120psi seem low for a stock engine.

[Billman]

Doesn't different cams give different CR numbers?

[aronmatic2]

The numbers are not so important, the most important thing is the difference.
I think, if you have more than 20% between lowest and highest, you have to rebuild the head in the late future.

check the breathing system first. i allways removed, right after i bought a 20vt.

[popdemonic]

thanks for your inputs mates!Aron,you said you removes the the breather system?so how to remove them and reroute the breather system hoses?i still keep everything stock except adding the Provent 200 catch tank on it.

@Billman,i use the stock AAN Cams at the moment.

@Andy 140 and 165psi i think it's still in maximum permissible variation on CR# between the cylinders.i had been running one old AAN with

120 psi all 5 w/o blowing that much oil fumes in the breather system.

@Dmitri,i'm gonna pull off the 034 billet valve and have a closer look on it.i remember you told me about 034 billet valve failure once for a while.that's

suck mate.

[Mikes2]

The spec for compression is 9-13 bar.

Wear limit is 7 bar.

Max difference between cylinders is 3 bar.

Engine is still within tolerance

[popdemonic]

one thing,I seem to have some problems on my head since everytime when i first cold start in the morning.I got a bluish smoke out of the exhaust tips.
it's just a single puff of smoke.I have also visually checked on my turbo.it's still good.I'm so confidenced that my valve stem seals are shot from my experiences.I really don't know if it can cause the pressure to be pushing out oil through out the breather system.I have some oil leaky through out
the valve cover gasket as well.i have been replaced it for a couple time but seem to have some oil leaking.it's not much but enough to be noticed.i
know this's probably some excessive pressure pushing the oil out.I'm not going to rebuild my engine soon since it's cost me a fortune to be tearing engine
apart.I also have a full block AAN laying around.I still haven't made up my mind if i will be replacing the rods with forged one.I have GT2871 running on E85 with 26psi of boost.so far it's pulling like a train but not sure if i need some more extra from the bigger turbo or just stick with GT2871.that's why i'm thinking about upgraded the Rods.TIA.

[prj]

Well, it will just get worse and worse.
I don't think it takes a fortune to rebuild this engine, it's actually pretty cheap.

[popdemonic]

Dmitri,

I'm thinking once i start to tear apart the motor.it needs a lot of parts.Full Head Gasket seals kit,Forged Rods,Piston rings,honing the block if needed?,new valve guides etc.Fully rebuilt the head?Damn too much parts but too less time and $$.

[caterpillar]

to check out the low comp; have some oil in syl...3 pump with some oilcanister...2-3 spoon... some rise of comp= headjob and valvejob are loose... very mutch rise of comp; the ringland and piston, or syl are worn out... total rebuild job...under 300000km??? no chance for any rebuild... nothing worn out..exept cracs in 3.syl piston.. then you does have the oilring seal at the HOT side of turbo...its classick.

[prj]

Dmitri,

I'm thinking once i start to tear apart the motor.it needs a lot of parts.Full Head Gasket seals kit,Forged Rods,Piston rings,honing the block if needed?,new valve guides etc.Fully rebuilt the head?Damn too much parts but too less time and $$.

I don't think it's that big of a deal. It is doable with a budget of about 800-900 EUR.
If you rebuild with stock rods, 400-500 EUR.

Of course if you pay someone to do the work, it's a different story.

You will have to do this in the future anyway. I don't see what the fuss is about.

[fundahl]

Hmm, I have the billet 034 checkvalve on the way... Where is the best place to tap to measure crankcase pressure directly?

[prj]

Hmm, I have the billet 034 checkvalve on the way... Where is the best place to tap to measure crankcase pressure directly?

Throw the checkvalve in the trash if you value your motor.

[jaychen]

Prj,

Do you suggest removing the breather system completely on an AAN ?