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Excessive crank case pressur

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93_tsi_fwd

15+ Year Contributor
2,625
16
Dec 20, 2006
San Jose, California
Sup guys,

I just recently blew/replaced the head gasket on my car. Now, im getting an excessive amount of crank case pressure. I am running a catch can and no PCV valve.(both valve cover ports go to catch can) If I remove the oil cap while engine is idling, it blows tons of white smoke/steam, as well as the catch cans vent. Imma be doing a compression test tonight. I also notice that my vacuum pressure is lower than normal. Was 18-20 in/hg and is now at 10-12 in/hg.

Let me know what you guys think. Its my only car right now plus i have my 10month old son inside and blows smoke inside from the vents.
 
exact same problem just haven't removed the oil cap.
 
Sounds to me like you may have blown more than the head gasket. I think that you may have broken some ring landings on a piston. I have wrecked a piston pretty badly and it was hardly visible from the top.

Let us know how the compression test goes. It is also possible that the new head gasket just isn't sealing. Was the head surfaced while it was off?
 
Cyl#1 125
Cyl#2 30
Cyl#3 125
Cyl#4 130

I tried to get cyl#2's compression up by warming it and adding couple drops of oil but nothing.

Wierd thing is I blew out #3 but number #2 got affected?:idontknow:

Might have cracked a piston or ring? Also I put a drop of oil on my finger nail and shined a flash light on it and see metal shavings. Im fvcked either way. Gonna need a new or rebuilt block.:ohdamn:
 
Leakdown test? Have you ruled the valves out?
Low compression + excessive crankcase pressure = narrowed down to piston or rings.
If it were a valve issue, cylinder pressure would be leaking into the intake or exhaust ports, which wouldn't affect crankcase pressure.
 
update. Here is what i found after i took off the head last night. This wasnt there when i did the head gasket couple days ago. What caused this? Valve are okay.

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Well, from the picture there aren't signs of massive detonation on that piston. I think you will really be able to see once the piston comes out of the block but my guess is maybe a broken ring that got stuck and then very hot. How does the cylinder wall look with the piston at the bottom of the stroke?
 
The cylinder wall has little scoring. Pretty sure a honing tool will take care of it. Time to get new piston rings and 1 piston.

From what ive been reading, its cause my lean conditions. Is cyl# 2 common? cause most of the threads i searched came out with cyl# 2 detonation.
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I'm with Paul on doubting that a hone will clean up the bore that that piston came out of. But hey it would be worth a shot, hone it out and then measure the bore to verify that it can still be used.

In my engine I lost number 2 as well but my piston looked way worse than yours. (I was tuning on the dyno and I was sure I had phantom knock so I turned off my knock sensor, big mistake)
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This came from a block that was already .020" over and I didn't want to go to .040" so I scrapped the block and got another to start over with.
 
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