Removing rear plenum

[Citgot]

I did a comprehensive search but could not find any posts with similar problems like mine.

 

I’m replacing the AOS but can’t get the rear plenum loose. After loosening the four clamps I can’t break the plenum free from the rubber sleeves on either side. I’m trying to rotate the plenum which worked with the front plenum. But I can’t find the strength needed. I also tried some filter tools for better grip and torque but no luck.

 

Anyone had the same problem and know a good solution?

[DBJoe996]

All I remember is that I removed the bolts from the left intake manifold and then moved it over to get the rear plenum out.  Actually, did not have to totally remove the rear plenum, just moved the intake manifold over and removed.  Just remember the rear plenum has a vacuum line attached that is a real pain to reach.  Good luck!

[Citgot]

Ok, thanks. Will try to remove the bolts without removing the rear plenum first.

[Citgot]

Been trying to get the intake manifold out with the rear plenum still attached but can’t seem to make it. There are too many hoses and cables in my way. I need to get the front end of the intake more to the left to wiggle the plenum out but there is no room because of the two hoses that goes to the left of the manifold.

So any more tips and tricks for me? What hoses are safe to disconnect to make more room?

And yes, i got all the bolts to the manifold out without removing the coolant tank.

[DBJoe996]

You have removed the nuts from the motor mounts so you can drop the engine (with support) down to the cross-member...right?  You have got to remove or disconnect most of the hoses and lines on that side of the engine in order to get the intake out.  Even the AOS coolant hose.  This is an extremely complex, intrusive and tedious job.   I pulled my entire rear bumper and heat shields on both sides so I would not damage them lowering the engine down to the crossmember.  The mufflers on either side would have bowed out the heat shields and bumper and probably, if not done, would have resulted in permanent damage.  In a word, take out everything on that side. Having the secondary air system out helps.  Having the alternator out helps.

[Citgot]

Well, no. I’m following the instructions in 101 projects. The motor drop should not be necessary. If I just could get the plenum out it would be rather easy to wiggle the manifold out between all hoses. But not with the plenum still attached as it obstructs all movement of the manifold.

I guess I have to do it the more time consuming way after all and dismantle more stuff

[JFP in PA]

1 hour ago, Citgot said:

Well, no. I’m following the instructions in 101 projects. The motor drop should not be necessary. If I just could get the plenum out it would be rather easy to wiggle the manifold out between all hoses. But not with the plenum still attached as it obstructs all movement of the manifold.

I guess I have to do it the more time consuming way after all and dismantle more stuff

 

Pelican is infamous for publishing questionable maintenance procedures, just look at their IMS procedures, which resulted in more screwed up engines than you can imagine.

 

I did this for a living; drop the engine down a couple of inches and you will be done with the AOS in one hour.  Pull the intake off and you will have hours of reinstalling, followed by hours more of smoke testing to find the vacuum leaks.  View simply is not worth the climb.

[Citgot]

Oh, ok. I thought I could trust Pelican at least enough not to break anything.

I’ll take your advice and drop the engine. Maybe I’ll check my motor mounts at the same time. Thanks!

[Citgot]

Ok, the 101 Projects instructions didn’t include the coolant hose to the AOS. I guess I’ll have to drain the coolant system as well then.

I guess you were right about the instructions... :)

[JTT]

On 3/22/2020 at 4:53 PM, JFP in PA said:

I did this for a living; drop the engine down a couple of inches and you will be done with the AOS in one hour.  Pull the intake off and you will have hours of reinstalling, followed by hours more of smoke testing to find the vacuum leaks.  View simply is not worth the climb.

 

JFP, as I remember, you can drop the engine down to crossmember level without disconnecting anything but the airbox?  Anything you can think of that has to be disconnected before dropping it down?

[JFP in PA]

47 minutes ago, JTT said:

 

JFP, as I remember, you can drop the engine down to crossmember level without disconnecting anything but the airbox?  Anything you can think of that has to be disconnected before dropping it down?

 

Not really, other than the battery (always be safety mined).  The trick here is you are only dropping it a couple of inches to give you access to the AOS.  As long as you don't go nuts with the process, it is quick and simple.  We always used a fabricated cradle to hold the engine while doing this, but it can be done with a block of wood and a jack if you are careful.

[JTT]

Thanks!

[rockhouse66]

Keep an eye on the O2 sensor cables when dropping the engine down to be sure they don't reach their limit of travel.

[Citgot]

Ok, i’m getting somewhere. But I can’t work out how I get the AOS seated all the way in. The bolts line up perfectly and are easily turned all the way in. But the peg going into the engine is stopping a few mm too far out. I can still see the red seal. Any tips on how to knock it in without cracking the AOS?

[JFP in PA]

Did you lubricate the seals before installing?  A little silicone lube goes a long way here...………...

[Citgot]

Thanks. Yes, I did use a small amount of lube on it, it should be enough. Didn’t want to over do it as a was afraid that it would not seal properly if there was too much.

The old AOS had a small o-ring that came out so there shouldn’t be one stuck in the hole.

I guess I’ll have to redo it and lube some more.

[DBJoe996]

JFP is right, lube it up.  You can also use a smear of clean synthetic engine oil.  It must go in and seat.

[DBJoe996]

Is that an OE Porsche AOS?  I remember seeing a picture of the old style AOS with the small seal on it, but the new OE AOS has a different  seal.  I'll see if I can find a pic.

[Citgot]

Is that an OE Porsche AOS?  I remember seeing a picture of the old style AOS with the small seal on it, but the new OE AOS has a different  seal.  I'll see if I can find a pic.

Yes, the new one is OE Porsche. The seal is different from the old one.

[DBJoe996]

Very difficult to make this out.  Even with the face of the AOS on the block, it still looks like a few millimeters off from the pipe being in the hole.  Stumped me.  Cram a shop light back there and get some better light on the subject.

 

Edited March 26, 2020 by DBJoe996

[DBJoe996]

This is why I'm wondering...see the seal on a new OE AOS?  It is not like yours, at least from what I can make out.

 

[Citgot]

Thanks. Your picture shows exactly the same seal as my new AOS. My seal is about two thirds in the hole in my picture. Maybe that is why it looks different?

[Citgot]

Nah, I have to give up for now. Can’t get it to seat properly. Removed it about ten times but it gets stuck every time a mm or two before it bottoms out. I would guess I’d have a leak if I used the car this way. Tried hammering it in but it will not move any more inwards. There is nothing obstructive in the hole, I’ve cleaned it.

Anyone have any more ideas? Picture from under the car. Looks the same with bolts attached, they don’t help.

[JFP in PA]

Something is seriously wrong here.  We have never had to "hammer" an AOS into position, the normally just pop in with minor pressure.  Are you sure you have the correct AOS?  Are you sure it isn't hitting something that is preventing it from seating?

[JFP in PA]

On ‎3‎/‎26‎/‎2020 at 3:14 PM, Citgot said:

Ok, i’m getting somewhere. But I can’t work out how I get the AOS seated all the way in. The bolts line up perfectly and are easily turned all the way in. But the peg going into the engine is stopping a few mm too far out. I can still see the red seal. Any tips on how to knock it in without cracking the AOS?

 

Was this photo taken from under the car?  The AOS looks' like it is hitting the case to the left of the tube....