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Catch cans and crank pressure

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Old 01-22-2015, 04:08 AM
  #46
Tom M'Guinn
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Originally Posted by 67King View Post
A catch can won't really help. The AOS is the cork. Take a soldering iron and open up the hole in the top of it.
Have you done this yourself? Any issues?
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Old 01-23-2015, 12:55 PM
  #47
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Why not to add a PCV to improve crankcase ventilation ?
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Old 01-23-2015, 02:50 PM
  #48
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Does anyone know or can possibly check what the factory spec is for crankcase vacuum?
I know some turbos will smoke if no vacuum is present in the crankcase but how much vacuum should there be.
Just enough to stop a smoking turbo?
What about the rings?
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Old 01-23-2015, 04:24 PM
  #49
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Originally Posted by Teddy952 View Post
Does anyone know or can possibly check what the factory spec is for crankcase vacuum?
I know some turbos will smoke if no vacuum is present in the crankcase but how much vacuum should there be.
Just enough to stop a smoking turbo?
What about the rings?
I've never seen a factory spec for that. That doesn't mean there isn't one, but would think I'd have stumbled across it by now... I suspect the factory airbox and snorkel creates slightly lower pressure in the j-boot, compared to all the MAF and MAP cars that have virtually no restriction in front of the turbo. Would be interesting to check with and without the factory airbox/snorkel. I got smoke at idle for a while, but putting an oil restrictor in my turbo seems to have cured that. I'll check my crankcase vacuum (if any) at idle next week and report back.
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Old 01-26-2015, 07:09 PM
  #50
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After mulling a bunch of options, it finally dawned on me to tee into the vent line going from the AOS to turbo mount. I looked and confirmed the hole in the AOS is much bigger there, and I can put a check valve before the catch can so that port will only vent when the crankcase is under pressure. That's mt latest plan anyway...
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Old 01-28-2015, 02:30 PM
  #51
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Top AOS hole does look very restrictive.

Ive popped it open and just drilled it to a matching diameter.





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Old 01-28-2015, 02:40 PM
  #52
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If you can get the top off without damage, then that's the way to go it would seem. I had a few old (gross) spares. I was able to get the tops off, but the tabs were worse for wear as a result, and I'm reluctant to try popping the top off with the AOS in the car. If it doesn't go well and the AOS is damaged, I'm really not excited about changing the AOS out. The second vent/drain port just under the top already has a nice big opening (maybe 15mm in diameter, compared to 5mm on top), so that seems like the next best option.

Edit: I also tried opening the hole with a soldering iron on the spares, and it wasn't comforting. The plastic melted and hole got bigger, but the plastic sort of crystalizes and little chips fell off (into the AOS), so I wasn't excited about doing that to the AOS on the car.
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Old 01-28-2015, 03:01 PM
  #53
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It comes off easy and I didn't cause any damage, not even cosmetic.

It is advisable to clean the inside of AOS as mine was covered with flaky oil residue in the inside. It would be a sin to use old AOS with this $hit inside on a new engine..


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Old 01-28-2015, 03:18 PM
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Did you remove it while the AOS was in the car? How did you do it?

I struggled to get the tops off the spares, and that was on a bench with access from all angles...
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Old 01-28-2015, 04:58 PM
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No it was on the bench. You just pull away each tab with screwdriver and lift it for 1mm or so, after fourth tab it just pops open.
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Old 01-28-2015, 08:19 PM
  #56
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Originally Posted by Tom M'Guinn View Post
If you can get the top off without damage, then that's the way to go it would seem. I had a few old (gross) spares. I was able to get the tops off, but the tabs were worse for wear as a result, and I'm reluctant to try popping the top off with the AOS in the car. If it doesn't go well and the AOS is damaged, I'm really not excited about changing the AOS out. The second vent/drain port just under the top already has a nice big opening (maybe 15mm in diameter, compared to 5mm on top), so that seems like the next best option.

Edit: I also tried opening the hole with a soldering iron on the spares, and it wasn't comforting. The plastic melted and hole got bigger, but the plastic sort of crystalizes and little chips fell off (into the AOS), so I wasn't excited about doing that to the AOS on the car.
I was able to open the small hole with a dremel/small grinding attachment. The AOS was off the car.
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Old 01-29-2015, 01:37 AM
  #57
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Originally Posted by Voith View Post
No it was on the bench. You just pull away each tab with screwdriver and lift it for 1mm or so, after fourth tab it just pops open.
In what condition was the seal after removal?
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Old 01-29-2015, 07:04 AM
  #58
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If you remove the top, why not go all the way and install a much bigger fitting? I will attempt to do this while the AOS is installed. Fingers crossed nothing will break.
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Old 01-29-2015, 07:13 AM
  #59
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Increasing diameter reduces the flow with the same level of vacuum. Not sure how far we want to go... would be nice to have a guy with a 100% stock engine plot vacuum in the AOS pipe in function of load.
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Old 01-29-2015, 09:02 AM
  #60
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In my case there is no vacuum since the output goes to a bottle. My main concerns is to get the positive pressure vented out of the engine.
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