'99 996 - oily at top of head, bank 4,5,6

[phil53chevy]

hello all, new to forum. just aquired a 996 cab with slipped sleeve for ...not much ? Just made the cam removal tool but noticed, prior to dissassembly,at the black plastic fitting or pipe on top of cylinder 4, that there is a proloferation of oil around the top of cylinder 4 that looks to have "blown across the even side" of the engine. I want to make sure it does not reoccur after repair of engine and install. There is an "o" ring that looks suspect.

What gives ?

[logray]

I've often wondereded this myself, but I think it serves as another method of pressure relief, perhaps due to overfill or excessive crankcase vacuum or ventilation?, or is even normal functionality of the engine/AOS design. I haven't read up much on this, sorry.

Here's what I've observed/thoughts:

Certainly replace the AOS "breather" as it's called.

Replace the o-ring

Even though this probably isn't necessary used some selant around the breather above the oring on top of the head.

Even after all of this and a couple thousand miles since replacement, I've noticed mine still "weeps" a tiny little bit of oily mist/vapor, but not like it's pouring out oil or anything.

[rb101]

When my AOS went bad, it was blowing oil out this vent and was slowly dripping down by 4 & 5. New AOS, fixed the problem.

[logray]

(I looked for official documentation, but all I could find were forum posts...)

When/if the AOS fails and creates abnormally high crankcase vacuum, the spring in the crank case/AOS breather opens (more?), thus spewing more oil out than it normally would.

It could be a leaky AOS tube as well, the tube that goes from the 4-6 head to the AOS can become brittle and crack, and while it doesn't cary flowing oil, there is fine oil mist. There are also o-rings on either side of the two AOS tubes.

You could use a thicker o-ring if it's not a good seal.

You should use a little tire sealant around the o-ring to help provide better seal during installation.

Don't overtorque the breather to the head, since it's plastic it can deform.

Edited March 3, 2012 by logray

[phil53chevy]

As the engine is apart COMPLETELY as of yesterday (first time 9-11 disassembly), almost d-chunk, just cracked, # 3 cylinder ! The OAS would be best to replace now while rebuilding. What a blast I had tearing down the motor. Facsinating engineering. that bearing carrier is a beast.

The most time consuming task was making the tools, but now I have them.

Advise on thread/link to rebuilding specifics, hints and tricks ? best parts supplier ( cost $$)

Any alternative to LN Nickies ?, Can I go to 3.6 without new injectors and reprogram engine management? Update IMS to new ceramic bearing and larger flange/bolt ? common parts to replace while she's apart ?

I think I may run a rubber hose pipe to from the vent to the underside of motor. Would then be easy to tell when I am getting "blow by " from failed OAS.

Thanks for all your help. great site

[phil53chevy]

picture of cam bearing cap upon tear down. Cap has hand written markings 7170 "E" for intake, 7170 "A" for exhaust....are these factory markings or has engine been torn down after dealer replacement in '05 ?

Just trying to figure out who has been in there and did they do the work properly

[logray]

picture of cam bearing cap upon tear down. Cap has hand written markings 7170 "E" for intake, 7170 "A" for exhaust....are these factory markings or has engine been torn down after dealer replacement in '05 ?

Those cam bearing marks could be from the factory, or they could be from a previous tear down, perhaps during refurb or perhaps later during an actuator replacement..

There should be identical numbers stamped on the perimeter of the cam cover and heads, to show which bearing caps match which heads and covers (they are a matched set).

This is all spelled out in the work shop manual, you do have a copy of that and have read through it right?

[logray]

Advise on thread/link to rebuilding specifics, hints and tricks ? best parts supplier ( cost $$) Any alternative to LN Nickies ?, Can I go to 3.6 without new injectors and reprogram engine management? Update IMS to new ceramic bearing and larger flange/bolt ? common parts to replace while she's apart ?

Best of luck to you if you decide to emark on this endeavor. Tearing down the engine is one thing. Rebuilding it is an entirely different ball game. I did this on my own but it was quite a challenge. I spent countless hours (over the course of several months) researching. The actual rebuild process took 4 months of rebuilding time (turn around for Nickies alone is 1-2 months), and I spent nearly $12k (LNE nickies, R&R rods, etc).

If you are going to do it on your own, I highly suggest you attend Jake Raby's M96 engine rebuild class this spring, I think he still has a few slots, and it is in a month or two. Well worth the money compared to the cost of the rebuild. Unforatunately the timing of the class didn't work out for me, otherwise I would have gone; I may still go some day. You are going to learn stuff in the class you never would by just reading a manual or reading someone else's thread. Best parts suppliers are Sunset and Sonnen Porsche, but sometimes rmeuropean, autohausaz, pelicanparts, and suncoast porsche.

Here's my thread, it's not all in there, and I certainly am missing some things a veteran at M96 rebuilding would be doing, so don't take my thread as a "DIY" on how to do it. You need to invent, have tons of spare time and money to be successful (and even then, one big mistake, and you need to be prepared/accept the fact that you might lose it all).

http://forums.rennlist.com/rennforums/996-forum/672370-engine-rebuild-part-3-the-finale.html

There are other options. You can buy a used engine, there was one for sale with low miles on RL.com a few days ago for $7,000, and I've seen them go for $5000-$6000.

For roughly the same cost as it will take for you to properly rebild your engine, you can buy a new Porsche engine (about $14k last time I checked), granted it won't have the upgraded internals such as Nickasil, JE pistons, etc.

You can also send your car to Jake at flat 6 innovations, and he'll turn it around in perfection for about $16-20k, if you can wait - he did say he has a few slots open in the very near future.

If you cut a ton of corners you might be able to do it yourself for $8-10k which would still include a lot of new parts, but why would you want to go cheap if you spend $4000 on new cylinders and pistons????... you're throwing money away if you don't go all the way and an old used part fails and destroys the engine. There are alternative sleeve supplies that do cast iron with stock pistons, but their options are just $1000 less than LNE. Hartech in the UK does the same thing LNE does.

No, you can't go without new injectors, engine manangement wouldn't need to be reprogramed regardles.

Yes I would update the LNE bearing. Replace as many parts as you can afford. You need to ask yourself during the rebuild, do I really want to reuse that drive chain that only costs $40, or do I really want to button up the bearing carrier without properly measuring and re-aligning bore if necessary and using the same bearings? Do I really want to reuse the same rods without upgraded ARP bolts? Do I really want to put the same old tired variocam actuators in the engine and know I'll be tearing into it again in short time? Jake tells us the easiest way to lose $12,000 in parts rebuilding the engine is to not spend $1000 on a critical piece, such as upgraded rods and bolts, or re-using chains, or reusing the IMS paddle, etc.

[phil53chevy]

Thank for the quick response and suggestions. Yes, I have the shop manual on my lap top in the garage and have seen your DIY engine rebuild as well as the boxster rebuild, m92(?), on youtube. I can tell there are many missing "steps". That's when I bought the shop manual. Probably won't sanitize my engine bay though ; ).

I saw the class advert on the flatsix web site and it looked very interesting. I don't like to reinvent the wheel and once I've seen it, I got it. made tons of sense. I'll have to check my calendar. I am a mechanical engineer by degree and an x- BMW dealer technician... have owned 944, 944s and 944 turbo, ford, chevy, isuzo, etc since I was 16 and torn them all down and rebuilt trans,replace clutches, engines, rear ends, etc..I am experiened.

I am sure I used no less than 100 zip lock bags ( sorry about the lunch bags kids) and zip ties to cartegorize parts and went through two purple sharpies (BTW- xtra large zip ties are the best thing in the world for dissassembling and removing engines and particularly for holding up 996 half shafts and other large components, just cut them or release the "clicker " when your done). but what fun. I hear you loud and clear about the checking and re-checking of specs during assembly. New variocam actuaters, rod bolts, IMS are,at the minimum, a few of the definites. No plan to reuse old drive chains, that make no sense.

I'll keep you posted on my progress and communicate as I proceed to avoid any "oh s#$%" moments.

Thanks

Phillip

[phil53chevy]

logray- how do you post pictures or links? each time I try to post a pic file, I get "the file too large " reply, other than the one bearing cap post above.

Is there FAQ on the site to view ? thanks

[logray]

Best of luck, hope it goes well...

Posting a pic, upload it to imageshack.us, photobucket, picasaweb, etc.

Then copy the link to the pic, and click on the picture button in the toolbar (below the smiley/font buttons). Then paste in your picture link.

Alternatively you can resize your pic and upload it here, but I'm not sure the size contraints which is what you're running into... haven't gone down that path..

[phil53chevy]

Best of luck, hope it goes well...

Posting a pic, upload it to imageshack.us, photobucket, picasaweb, etc.

Then copy the link to the pic, and click on the picture button in the toolbar (below the smiley/font buttons). Then paste in your picture link.

Alternatively you can resize your pic and upload it here, but I'm not sure the size contraints which is what you're running into... haven't gone down that path..

thansk , BTW, what is your name ? it's not Logray I assume.

[logray]

Just a handle, LOL.

-Logan