Just picked up a non-running 996; where to begin?

[Bay Arean]

Thanks, guys, this is really valuable stuff. Fortunately my Bentley book and camshaft alignment tool arrived today. I bought a tool kit that contains the camshaft retainer (looks like a flat bar with tabs at the end for fitting into the camshaft slots).

My cams probably aren't at TDC right now. With the cam cover still installed, do you think I'm good to use a steel bar (much like a huge flat blade screwdriver) to rotate the cams to their TDC position? I believe TDC would be both slots inline with one another.

Then I could slowly release the cam cover with no extra pressure on the lobes.

[JFP in PA]

Thanks, guys, this is really valuable stuff. Fortunately my Bentley book and camshaft alignment tool arrived today. I bought a tool kit that contains the camshaft retainer (looks like a flat bar with tabs at the end for fitting into the camshaft slots).

My cams probably aren't at TDC right now. With the cam cover still installed, do you think I'm good to use a steel bar (much like a huge flat blade screwdriver) to rotate the cams to their TDC position? I believe TDC would be both slots inline with one another.

Then I could slowly release the cam cover with no extra pressure on the lobes.

 

You are heading the correct direction, but as I mentioned earlier, I like to add the extra cam bearing caps to make up for the ones cast into the cover before starting rotation to help distribute the load on the cams.  You may also find that some of the retaining tools with the flat tabs may not fit into the cam ends with them being off TDC.  That is why a tool with a round Allan head bolt (like the fabricated tools above) works better at holding the cams in those situations.

[Bay Arean]

I enlisted some friends to help drop the engine this weekend. Following the Pelican Parts "engine drop" technical article made it very easy and only 1 or 2 wires/hoses were missed.

I took advantage of having the engine on a stand to do a very thorough pressure washing (did the transmission, too). Boy, I'm excited to get that clean motor back in the trunk.

I'm a bit dismayed by how complex the "auxiliary" systems attached to the engine are. It will be hours and hours before I can so much as take the valve covers off due to the sheer number of hoses, wires, nuts and bolts are attached to the engine. Getting everything back in its original position will be very difficult.

I initially tried to separate the entire intake manifold as one piece, but I think I will reassemble before it's too late and go one piece at a time, from top to bottom. Trying to imitate Porsche's original assembly process. I'll upload some photos of status when I have PC access. Anyone have recommendations on resources that could help with this challenge?

[Domiac]

I'm a bit dismayed by how complex the "auxiliary" systems attached to the engine are. It will be hours and hours before I can so much as take the valve covers off due to the sheer number of hoses, wires, nuts and bolts are attached to the engine. Getting everything back in its original position will be very difficult.

 

Once you put it back together, many parts fall in place naturally. Nevertheless, I recommend one to use e.g. zip ties and use permanent marker to write matching numbers between parts or something similar, that is quick to do and idiot safe. Take also bunch of pictures with your digi camera from different angles just to be on the safe side.

 

Before you start wrenching plastic intake manifold back in place, attach all parts together first loosely, then check for alignments between the parts and adjust tube positions (push deeper together or pull shallower). You'll notice how this will affect getting a perfect fit between the plastic and aluminum parts by adjusting angle of the whole manifold.

 

BTW Do you plan to do some kind of vacuum test for your engine? Now would be the perfect time to do it and see where it leaks, it's a perfect moment to change some lines or oil checkup tube etc.

[Bay Arean]

Hey all,

 

Separated the engine halves tonight after many hours of tediously removing auxilary components and labeling. I hope I've been organized enough to get it back together correctly! Damage so far is 8 bent valves on cyl 1-3, broken timing chain, and gouged chain rail. Cylinders look good, thank goodness.

 

The timing chain for cylinders 1-3 was broken and wedged tightly between the IMS sprocket and the case. Only after the engine was separated was I able to knock it loose. I noticed that as I turned the crankshaft, the sprockets connected to the cam chains did not turn. I assume this means my IMS has been destroyed because the sprockets are freewheeling? Or is there some attachment point for the large sprocket?

 

Questions:

• Is my intermediate shaft destroyed? Or is there normally a shear pin or something else holding the sprocket from turning on the shaft? 
• If my shaft is bad, does anyone know the correct p/n for a 3.6L engine? eBay has some intermediate shafts available for ~$400 but they're from 2.5L engines. Pelican sells new shafts (p/n 996-105-901-06) for $1400, ouch.
• Can I use a regular ring compressor to get the pistons back into the cylinders? Can anyone shed light on the procedure? Seems tough since there's not much access...
• I bought the $800 LN Engineering IMS bearing kit. Do I still need the LN Engineering tool kit ($350) since I'm splitting the case and already have lots of access?
• Is there a tensioner for the crank-to-IMS chain? I couldn't find one.

I assume the next steps will be to loosen the tensioner for the cylinder 4-6 cam chain and remove the IMS. Engine is currently at TDC so I shouldn't have any issues with valves moving around.

Edited July 31, 2015 by Bay Arean

[Bay Arean]

One more photo. This shows the end of the IMS. This is the sprocket that is slipping on the shaft. Why?

Edited July 31, 2015 by Bay Arean

[Domiac]

• Is there a tensioner for the crank-to-IMS chain? I couldn't find one.

 

IMS to crank chain tensioner is quite obvious, see the links in this msg. But you already split your cases so you are probably talking of something else?

 

Navigate to

https://www.dropbox.com/s/rkr4wuilr1o9slx/996-3_chain.png?dl=0
https://www.dropbox.com/s/52v4fgt1igarbzd/996_IMS_upgrade_tensioner_removal.jpg?dl=0 

PS. How the heck I nowadays add new images to Renntech? "Link" gets garbled into renntech.org based and "Image" just hangs when pointing to external website.

Edited July 31, 2015 by Domiac

[Bay Arean]

 

 

IMS to crank chain tensioner is quite obvious, see the links in this msg. But you already split your cases so you are probably talking of something else?

 

Navigate to

https://www.dropbox.com/s/rkr4wuilr1o9slx/996-3_chain.png?dl=0
https://www.dropbox.com/s/52v4fgt1igarbzd/996_IMS_upgrade_tensioner_removal.jpg?dl=0 

PS. How the heck I nowadays add new images to Renntech? "Link" gets garbled into renntech.org based and "Image" just hangs when pointing to external website.

 

 

Hey Domiac, you're absolutely right. It was easy to spot. Guess I was working too late into the night!

I click "more reply options" and then an "attach files" option appears at the bottom. Can upload up to 2mb.

[JFP in PA]

Hey all,

 

Separated the engine halves tonight after many hours of tediously removing auxilary components and labeling. I hope I've been organized enough to get it back together correctly! Damage so far is 8 bent valves on cyl 1-3, broken timing chain, and gouged chain rail. Cylinders look good, thank goodness.

 

The timing chain for cylinders 1-3 was broken and wedged tightly between the IMS sprocket and the case. Only after the engine was separated was I able to knock it loose. I noticed that as I turned the crankshaft, the sprockets connected to the cam chains did not turn. I assume this means my IMS has been destroyed because the sprockets are freewheeling? Or is there some attachment point for the large sprocket?

 

Questions:

• Is my intermediate shaft destroyed? Or is there normally a shear pin or something else holding the sprocket from turning on the shaft? 
• If my shaft is bad, does anyone know the correct p/n for a 3.6L engine? eBay has some intermediate shafts available for ~$400 but they're from 2.5L engines. Pelican sells new shafts (p/n 996-105-901-06) for $1400, ouch.
• Can I use a regular ring compressor to get the pistons back into the cylinders? Can anyone shed light on the procedure? Seems tough since there's not much access...
• I bought the $800 LN Engineering IMS bearing kit. Do I still need the LN Engineering tool kit ($350) since I'm splitting the case and already have lots of access?
• Is there a tensioner for the crank-to-IMS chain? I couldn't find one.

I assume the next steps will be to loosen the tensioner for the cylinder 4-6 cam chain and remove the IMS. Engine is currently at TDC so I shouldn't have any issues with valves moving around.

 

The IMS shaft chain sprocket is pressed on, and have actually been known to slip on the shaft.  I would have someone with experience check your shaft and sprocket to see if they can still be used, and if they can, I would highly recommend having the sprocket pinned to the shaft to prevent it from ever moving unintentionally.

 

A replacement shaft is going to be an issue.  You will need to find a serviceable used one and get it pinned as discussed above.  Replacement shafts from Porsche are all going to be the non serviceable over sized third design IMS bearing, and would include the bearing, which is why they are so expensive.

 

Yes, an "off the shelf" adjustable ring compressor will work, but your larger issue is going to be how you are going to get the wrist pin locks back into place as it requires a special tool and forces you to work through a small opening, a process that has been likened to building a ship in a bottle.

 

With the shaft out of the engine, you can install the LN bearing using a bearing press, but if the shaft has the old bearing still in it, you are going to need the pulling tool to get it out before you can install the LN.

[Bay Arean]

I spoke with LN Engineering this morning and they took care of me. Unfortunately because my sprocket has already spun my IMS cannot be repaired. However, LN has reconditioned IMS's in stock and it will arrive already pinned and with the upgraded bearing installed for $1600.

As I was already planning on spending $1150 ($800+$350) for the bearing upgrade, this isn't terrible.

[Ahsai]

That's good know. Is it required to send back your broken IMS as a core?

[Bay Arean]

Actually the core has no value because the sprocket has already spun. Once it loses its alignment it can't be repaired.

[Ahsai]

Makes sense. Good luck with the repair!

[JFP in PA]

I spoke with LN Engineering this morning and they took care of me. Unfortunately because my sprocket has already spun my IMS cannot be repaired. However, LN has reconditioned IMS's in stock and it will arrive already pinned and with the upgraded bearing installed for $1600.

As I was already planning on spending $1150 ($800+$350) for the bearing upgrade, this isn't terrible.

 

Let me guess, this is one of their "triple" row IMS units, which are truly a beautiful thing.

[Bay Arean]

Indeed, this will be the "latest and greatest" new IMS bearing from LN!

 

Guys, looking at the engine this morning I'm not sure I'll be able to remove the IMS without also removing the 2nd cylinder head. Does anyone know whether it's possible to loosen the crank-to-IMS chain and far-side timing chain enough to remove the IMS? I've attached a photo of the engine up to now.

[JFP in PA]

Indeed, this will be the "latest and greatest" new IMS bearing from LN!

 

Guys, looking at the engine this morning I'm not sure I'll be able to remove the IMS without also removing the 2nd cylinder head. Does anyone know whether it's possible to loosen the crank-to-IMS chain and far-side timing chain enough to remove the IMS? I've attached a photo of the engine up to now.

 

With the crank at TDC, if you remove the  four chain tensioners, the chain on the IMS should easily go slack enough to be removed.

[Ahsai]

John, when you said triple row, are you referring to the gear/sprocket on the flywheel side of the IMS? Or are you referring to some new design of the LN bearing?

[JFP in PA]

John, when you said triple row, are you referring to the gear/sprocket on the flywheel side of the IMS? Or are you referring to some new design of the LN bearing?

 

It is the IMS bearing.  While not new, LN developed a super strong triple row version of their ceramic hybrid, which requires a special replacement shaft with pinned sprockets.  This is used only on disassembled engines as it is an entire shaft assembly with the bearing already installed, and requires splitting the cases to install.  Very few people have even seen this unit, but it is a work of art.  From their website:

 

"LN Engineering also offers an IMS Upgrade service where you send in your intermediate shaft and it is upgraded to a triple row bearing (with exception of MY06-08). Additionally, the main drive sprocket is pinned to prevent slippage of the drive gear, which is a known problem area."

[Ahsai]

Oh wow, that sounds interesting. I wish they had some pics of the said bearing and I wonder what's the recommended replacement interval of that, if any.

[Ahsai]

I may have found the pic...in the middle of the page here http://www.porscheenginebuilding.com/ims_upgrade.asp

[JFP in PA]

Oh wow, that sounds interesting. I wish they had some pics of the said bearing and I wonder what's the recommended replacement interval of that, if any.

 

You mean this:

 

[Ahsai]

Yeah, I wonder if this is the LN unit.

[JFP in PA]

Yeah, I wonder if this is the LN unit.

 

It looks like it to me.

[Bay Arean]

Hi all,

 

I spent the morning educating myself on the cylinder 4-6 wrist pin installation. I was blissfully unaware of that procedure until you guys brought it up. I was hoping to leave the cyl 4-6 untouched, since that side of the engine is healthy on my car. But it appears the 4-6 side must be assembled after the 1-3 side to the presence of the wrist pin assembly thru hole.

 

That being said -- does anyone have a wrist pin installation tool set they'd lend me? I think I could probably rig one up from Home Depot supplies but I'd rather have the right tool for the job (which is alternatively $300 most places). 

[JFP in PA]

Hi all,

 

I spent the morning educating myself on the cylinder 4-6 wrist pin installation. I was blissfully unaware of that procedure until you guys brought it up. I was hoping to leave the cyl 4-6 untouched, since that side of the engine is healthy on my car. But it appears the 4-6 side must be assembled after the 1-3 side to the presence of the wrist pin assembly thru hole.

 

That being said -- does anyone have a wrist pin installation tool set they'd lend me? I think I could probably rig one up from Home Depot supplies but I'd rather have the right tool for the job (which is alternatively $300 most places). 

 

I think you are going to find that those that have acquired engine assembly tooling are not going to be interested in lending or renting them out.  You might want to search around as there have been posts concerning fabricating these and other Porsche specific tools.