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- - Identify this part! (http://986forum.com/forums/showthread.php?t=63006)

Quote:

Originally Posted by stelan (Post 508863)

That part is part of the pcv
It is a spring loaded valve that prevents your seals to blow if too much pressure in the cranckcase is present.

If you have a semi operational AOS and bad spark plug tube seals the car leaks little oil if you disconnect or cap the throttle body to AOS hose the car with bad spark plug tube seals will leak a lot of oil because there is no vacuum present in the crancase and the pressure builds up and leaks like crazy.

You have, I believe a combination of the following:
A) bad spark plug tube seals AND
B) bad or going bad AOS diagragm (hissing)

Or
A) bad spark plug tube seals AND
B) vacuum leak

Vacuum leaks can be found at
-hose from drivers side vent valve to aos
-aos itself
-hose from aos to throttle body
-aos bottom bellow
-dipstick tube
-oil fill tube
-little hoses that go inserted into intake bellows
- little hose that connects to throttle body
- throttle body boots

Changing the spark plug tubes or/seals will stop the leak, replacing the AOS and/or finding the vacuum leak will stop the hissing noise and will fix your rough idle.

It is possible that your AOS is going bad and is creating excessive vacuum (negative pressure) in the crankcase and the hissing noise is actually air sucking thru the bad spark plug tube seals.

So I would replace all spark plug tube seals firts and go from there

Thanks for that really helpful post. Most of these things were things I was considering, and this really helps me know I'm on the right path. I had not thought about the dip stick tube, I did wonder if maybe air was getting sucked in through the spark plug tube, but hadn't considered that the AOS could play a roll in that. I ordered new tubes last night.

Quote:

Originally Posted by Timco (Post 508885)

I have some very sensitive manometers. Glad to help when I'm back in town if you're in SLC area. I can check very low vac or positive pressure in inches of WC.

OK, I'm in Southern Utah County and I just might take you up on that. :cheers: When are you back in town?

Quote:

Originally Posted by sleepingboxster (Post 508908)

OK, I'm in Southern Utah County and I just might take you up on that. :cheers: When are you back in town?

Fly back Tuesday. My shop is in SLC and I work in Orem.

OK. I replaced the spark plug tubes and Removed and reinstalled the existing AOS. The leaking tube had a missing chunk the size of a dime. I don't know if it broke when I removed it or if it was broken from putting a spark plug socket in there when I changed the plugs last month. I left the dime size piece of plastic in the valve cover as I couldn't fish it out and thought I'd cause more harm than good by removing the cover especially since I don't know when it broke off. I used the ERO brand tubes they were a very tight fit I really lubed up the rings then pretty much had to force it. They were 2mm longer than the original ones and at first I thought that may be the problem, but it's just tight O-rings. Idle is much better from 700 to 1050 RPMs instead of 11 -1500. It did not immediately turn off the check engine light, but I did reset it and after about 33 miles is has not come back on and there are no pending faults. I'm hopeful but there could be additional leaks - I was expecting no higher than 850 RPMs.(what is normal?) Hiss is gone. I'll give it another 60 miles and they put the carpet and rear speakers back in! Huzzah!

Cool, I hope problems are gone

Mine idles 840 RPM cold, 700 warm, rock steady.