[tamathumper]

Got the intake manifold off this morning, along with the air oil separator.



The intake bolts were not that tight, I was surprised how easily they came undone. There is a lot of oil gunk in the tips of the intake manifold and in the head itself, at least 1/16" thick sticking to the walls, and runny oil on the intake manifold gasket. There's also an oil flow down the side of the engine, pooling up under the air oil separator (or just ahead of it).







This is a close-up of the oil on the side of the engine and pooling up under the intake manifold, near the air oil separator.





I took the lid off the air oil separator using the "x-acto blades" trick mentioned by kwikt, and verified the o-ring at the top was in good condition. I then replaced the o-ring with a careful amount of RTV and put the lid back on, being careful to seal all of the slots and around the top of the lid with more RTV. It's now airtight, but it was pretty airtight already.

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[banditsc]

Make sure the plastic collar is still on the bottom of the dip stick tube.

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[tamathumper]

Do you mean the orange rubber ring? I took that out as part of removing the intake manifold, and it had a cut in it. A new one is on the way.

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[Cloud9...68]

I had mass quantities of oil and grease accumulated on the left side of my engine as well when I tore it down. For some reason, the o-rings and seals on these cars don't seem to hold up very well.

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[flash]

you cannot use RTV at the top of the AOS . the fuel vapor will dissolve it.

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[banditsc]

In addition to the o-ring at the base of the dipstick tube there is also a plastic collar, it's in the diagrams if your missing it.

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[tamathumper]

Well, poop. According to the literature, this Ultra Black stuff is resistant to oil and gasoline, and I figured there was a lot of oil and only a little gasoline.



"This is Permatex Ultra Black - Hi-Temp RTV Silicone Gasket Maker - Resistant to Gasoline, Resists Temperatures up to 500 Deg F. Performs well at low Temperatures. Effective on Uneven joint Surfaces, Seals in 60 Minutes. Great for Disassembled engines. 3.35 OZ Tube."

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[flash]

you need something designed to work with o-rings. ultra black is designed to go between 2 flat metal surfaces. curel is what porsche recommends.

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[tamathumper]

@bandit, got it, there's a "spacer sleeve" shown in the PET, and I do have that (white plastic) at the base of the dipstick tube.

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[flash]

by the way, the amount of oil you have at the intake ports is not encouraging. that is a tell-tale sign of valve seal leakage. that would also explain your vacuum leak and boost loss.



did you do a leak-down before you pulled the intake off?



p.s. - i think the bolts are only 15 lb/ft (i always have to look it up), so they would pop loose pretty easily.

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[tamathumper]

I was wondering where that oil would come from, it coats the whole inside of the intake manifold, although it's not visible through the throttle body. At 54,000 miles I wouldn't expect that much wear?



I did not do a leak-down, but that's on the list. There's definitely a big vacuum leak around the air oil separator, so that needs to be dealt with at the moment.



All parts of the air oil separator have been duly de-RTVed, and are awaiting a better sealant. That canister does not seal well, so it's going to need something besides the original thin o-ring at the top, or I just need to buy a new one.

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[tamathumper]

flash, I'll order up a tube of Curil-T, and I'll also order up a tube of Curel hand lotion if you really think it will help... <img src="/forum/images/smilies/968/biggrin.png" class="smilie" alt="" />

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[flash]

bummer - i would have done that prior to removing the manifold, as to fix it, likely requires removal.



there are really only a couple of ways for the oil to get into the intake:



if the vacuum hose to the AOS is not the hard plastic line with rubber ends, too much vacuum gets in there and it will suck the oil right out of the crankcase and dump it into the intake.



if the valve seals are leaking, or guides are worn, it will allow oil to pass and get into the intake. no quick fix there. head removal required.



if the rings are not sealing, you will literally pump oil into the intake. this was my problem, which led me to a rebuild

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[banditsc]

They are only $65 used from DCAuto.

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[tamathumper]

@bandit, thanks for the tip. This one cleaned up nicely, and I think another used one would have the same tiny o-ring and the same small leaks around the top. This one is in very good condition, I just don't like the seal of the top... I'll probably just put it back together with Curil-T, or I might use some of the MotoSeal 1 I read about - I have to talk to the adhesive/polymer chemists at work on Monday, we have a strong relationship with LocTite, Permatex, and many similar companies, and those guys will know what is recommended. If they don't know firsthand, they'll have a buddy in one of the labs *at* Permatex and it's always fun to talk to them. We had a great discussion about Kydex and thermoforming a new engine shield a while ago.



flash, when you say "if the vacuum hose to the AOS is not the hard plastic line with rubber ends" do you mean the very short line with a "J" bend that goes into the top of the AOS, or do you mean the really big line that comes forward under the intake manifold? Both of those lines on my car are original, so the short one is a hard plastic line with rubber ends, and the big one is the original all-rubber hose. The short line's connection to the intake manifold was very firm and hard to remove, but the one at the top of the AOS was fairly easy to remove, I guess because the plastic nipple on top of the AOS doesn't have a "bead" on the end, it's just a straight nipple.



I ask because I plan to change out my vacuum lines at some point and use the all-silicone hose I got from Lindsay Racing - are you saying that is not recommended?

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[flash]

i was talking about the skinny hard plastic one that has rubber ends. they use the hard line to restrict the amount of vacuum.



do not substitue any of the hard plastic lines with the silicone. under boost, silicone can expand and allow too much flow. under vacuum some devices, like the AOS only want a very tiny amount of vacuum, and the silicone hose allows too much. been there done that. had to get new hard plastic line.



it would be fine though any place there is already normal rubber vacuum hose.

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[tamathumper]

OK, that's good to know. The only silicone piece on there right now is the one from the supercharger kit. If it's OK, I may replace some of the rubber ends with silicone, it seems to have a much better grip than the old rubber.

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[flash]

i see no issues there. realize though that silicone hose tears pretty easily, so if you have to expand it too much to get over the nipple, it might not work

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[tamathumper]

Decided to put the air oil separator back together and test it for vacuum while I'm waiting for Auto Atlanta to deliver. I should not have ordered from them, but it was late and I was "in a hurry" - you know how it is. Now I'll be waiting a week more than if I had just waited and ordered from Sunset, although they had to backorder some of the parts, too. Today is the first "lie day", where they promised to get the parts in and turn them around and ship them back out to you, but did not...



Anyway, it holds just fine all the way up to 20 inches.



During the test, I hooked the boost/vacuum gauge I have been using all along up to one hole, then I hooked the Mity Vac up to another. When the Mity Vac was reading 20 inches, the other gauge was only reading 18! I don't know which one is more accurate, but the other one was a cheapo, and the Mity Vac is at least a brand name. I mean, I had air leaks, no doubt, but I feel better thinking I was running 18 inches of vacuum instead of 16, as there's a little less potential to be lean.



Onward and upward.

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[flash]

lol - if you have 18, you're done. that is what you should have.

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