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Porsche 911 Carrera Engine Tear Down
 
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Pelican Technical Article:

Porsche 911 Carrera Engine Tear Down

Time:

6 hours6 hrs

Tab:

$0

Talent:

***

Tools:

Camshaft holding tool

Applicable Models:

Porsche 996 Carrera models (1999-05)
Porsche 997 Carrera models (2005-12)

Parts Required:

â€"

Hot Tip:

Get two large folding tables to lay all of the part

Performance Gain:

Figure out what went wrong

Complementary Modification:

Install a bigger engine
This project focuses on a brief overview of the 911 Carrera engine and what it looks like inside. The engine featured here suffered a catastrophic failure, likely caused by a lack of oil to the main crankshaft. For the past 10 years, Porsche has offered an engine exchange program where you have to give back your old engine to Porsche when you get your replacement (known as a CORE charge). This means that very few of these engines have been floating around for people to disassemble, as we are doing here. We spent an entire two days at renowned Porsche workshop Callas Rennsport tearing down the engine and inspecting each component. For more detail on the teardown, I have made about 350 more photos of the disassembly process available with detailed captions on the 101Projects.com website. 
This particular engine was out of a Boxster, but the Carrera engine and Boxster
Figure 1

This particular engine was out of a Boxster, but the Carrera engine and Boxster engine are nearly functionally identical with the only differences being in various locations of accessory equipment and plumbing.

Here's the camshaft cover coming off of the engine.
Figure 2

Here's the camshaft cover coming off of the engine. It's always a good idea to mark parts so that you know where they go if you try to put them back together again. Here we have marked the camshaft oil scavenge pump so that we know exactly how to mount it again in the future (yellow arrow). It's important to note that the camshaft covers have an integrated camshaft bearing as well--the green arrow points to the section in the cover that holds the camshaft in place.

Here's a neat shot of the camshaft cover removed.
Figure 3

Here's a neat shot of the camshaft cover removed. The top camshaft is the intake camshaft, the lower one is the exhaust. On the earlier cars, they are tied together with a small chain that is attached to a tensioner/advance mechanism that slides back and forth and changes the relationship (in degrees) between both camshafts. This device is controlled by the solenoid in the center (yellow arrow). The green arrow shows the very useful camshaft holding tool that the fellows at Callas Rennsport designed to keep the camshafts in place when removing the side cover. As discussed previously, the camshaft covers contain the "bearing caps" that hold the camshaft to the heads, so when you remove the covers, the cams will pop out if they are not held in place.

The two camshafts are removed together.
Figure 4

The two camshafts are removed together. Yes, you can perform the camshaft removal and replacement with the engine in the car (the folks at Callas Rennsport have done that previously on a 911 Carrera), but it's neither fun nor pretty. Lots of careful maneuvering is required. Four bolts hold the top and bottom camshaft end caps. Remove them, but remember which cap goes where. The tensioner/advance mechanism pulls off with both the intake and exhaust camshafts.

With the camshafts out of the way, you should be able to pluck the camshaft hydraulic followers out of the cam follower housing.
Figure 5

With the camshafts out of the way, you should be able to pluck the camshaft hydraulic followers out of the cam follower housing. Use your fingers or a suction cup to grab them out of there and be sure to place them in a tray, marking which valve they are matched to. The Porsche factory manuals recommend against using a magnetic tool to pluck out the lifters. Doing so may cause damage, presumably if part of the lifters become magnetized. When you reassemble the engine, you want to make sure that you reinstall the followers into the same exact bore that they came out of. This will reduce premature camshaft wear.

This photo shows removal of the cam follower housing.
Figure 6

This photo shows removal of the cam follower housing. Removing this housing exposes the tips of the valves and each corresponding valve spring.

Remove the chain ramp bolts and then the chain ramps.
Figure 7

Remove the chain ramp bolts and then the chain ramps. Remove the head bolts and then gently tap the head with a hammer to release it from the case. It should slide right off. If it doesn't, you probably forgot a bolt somewhere. Here's a shot of the head coming off. Oops, looks like we're missing a valve (blue arrow)!

Yikes, there's that missing valve (blue arrow).
Figure 8

Yikes, there's that missing valve (blue arrow). It's quite obvious that we dropped a valve here, but it's not clear whether that happened before or after the rest of the damage to the engine. Note the cracks in the cylinder walls of the case (red arrow). This is not what you would call a re-buildable core.

This photo shows the damaged cylinder head.
Figure 9

This photo shows the damaged cylinder head. The red arrow points to the valve where the head broke off. You can see that the oil from the engine is a light brownish color. This means that coolant and oil mixed together--it's typically a very bad sign if you see this when you change your oil.

Here's the oil pump removed from the engine.
Figure 10

Here's the oil pump removed from the engine. A few small bolts hold this in place. Remove them, and it should be simply plucked off.

11
Figure 11

We went to look at the piston, and, oops, it just slid out as there's no more rod attached!

Moving on, we now removed the front oil pump housing from the engine.
Figure 12

Moving on, we now removed the front oil pump housing from the engine.

The oil pan on the bottom of the motor needs to be removed before splitting the case.
Figure 13

The oil pan on the bottom of the motor needs to be removed before splitting the case. These black plastic attachments are oil baffle plates, designed to channel and funnel oil in the sump of the engine.

Before splitting the case, we moved the arms on the engine stand so that we had three points of support instead of two.
Figure 14

Before splitting the case, we moved the arms on the engine stand so that we had three points of support instead of two. This engine stand is a generic one and thus doesn't support the engine as well as a Porsche factory tool. Make sure that you attach the stand to the half of the engine that has the water pump. This will allow you to easily lift the opposite side off of the engine. Rotate the engine so that the water pump side is facing down. With all of the bolts removed (see the 101Projects.com website for more info), you should be able to start prying the case to split the two halves apart. There are a few spots on the case where it's okay to pry them apart. Only use these areas, as you don't want to scratch the case surfaces. There's no seal or O-ring that goes in there--it's just metal-sealant-metal.

This appears to be where all the damage began.
Figure 15

This appears to be where all the damage began. This bearing (#1) is cooked completely and burned into the crankshaft. This is symptomatic of a drop in oil pressure. The bearing becomes very hot and then basically fuses itself to the shaft. Then the rod seizes and completely breaks. The rod for this cylinder was completely missing. We found it in a half-dozen pieces at the bottom of the engine (more photos on the 101Projects.com website).

With a friend near by, pry up the crankshaft bearing housing, and it should lift off of the engine with the intermediate shaft closely in tow.
Figure 16

With a friend near by, pry up the crankshaft bearing housing, and it should lift off of the engine with the intermediate shaft closely in tow. This is really a two-person job. I would not try to lift this your self, as the angle is all wrong.

Remove the bolts that hold on the oil baffle/separator, and remove the guide for the main chain.
Figure 17

Remove the bolts that hold on the oil baffle/separator, and remove the guide for the main chain. You should then be able simply to pick the intermediate shaft up and off of the crankshaft bearing housing.

Here's one of the pistons with the piston circlip, which is very difficult to install in the engine when it's being rebuilt.
Figure 18

Here's one of the pistons with the piston circlip, which is very difficult to install in the engine when it's being rebuilt. You need a special Porsche tool--and lots of patience. I have heard it's like playing that childhood game, Operation: one mistake and you can easily drop the circlip inside the engine.

This is something you only really see in modern carsâ€
Figure 19

This is something you only really see in modern cars--the bearing housing has a steel insert cast into the aluminum. This type of "insert molding" is presumably for strength around the bearing surfaces. After removing the bolts that hold the assembly together, gently pry it apart.

These engines use a cracked-rod design, where the rods are forged and machined, and then broken.
Figure 20

These engines use a cracked-rod design, where the rods are forged and machined, and then broken. Then the bearings are installed, and they are put back together again. This cracked-rod design is cheaper to manufacture, and the rod bolts don't need to have integrated "guide" pins as part of their design (like the rod bolts used on the older air-cooled engines). Unless you use some type of oversized bearing, you cannot rebuild or re-machine these rods.

Here's another shot of that cooked rod bearing.
Figure 21

Here's another shot of that cooked rod bearing. Definitely caused by a lack of oil. Perhaps the previous owner forgot to check their oil level?

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Comments and Suggestions:
Lee Comments: The link you provided below is for the 911 engine 1965 - 1989 not the 996 engine. In my search I found that page.
Thanks for all you do for Porsche owners.
http://101projects.com/911-Rebuild/Bonus_CD-ROM.htm
November 19, 2015
  Followup from the Pelican Staff: I was following the link, figured it may be there. We don't have anything additional then. I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Lee Comments: It looks like I’m going to have to rebuild my 996 M96 engine. In the engine section of the Porsche 911 1998 - 2005 Technical article under the link to “Porsche 911 Cerrera engine tear down” the description say there are more than 850 photos documenting the teardown of the 996/Boxster engine piece by piece...
On this page the caption under figure one it was for more details on the teardown with 350 more photos of the disassembly with detail captions go to the 101projects.com website. I can’t find any links other than this one.
November 12, 2015
  Followup from the Pelican Staff: Check this area of the page: http://101projects.com/911-Rebuild/Bonus_CD-ROM.htm - Nick at Pelican Parts  
tommie Comments: locking for main and rod journal dia specs 2001 996 engine?
thanks
September 22, 2014
  Followup from the Pelican Staff: I don't have that info handy. I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
bruce Comments: I have a 911 996 with 180k. Compressions are a little low but a leak test is showing valves on two cylinders are bad. I will have the heads done. But the question is should I complete work on the cylinders and crank while the engine is out. I am planning on installing a super charger.
August 27, 2014
  Followup from the Pelican Staff: If installing a supercharger, I would rebuild as much as you have budget for. Including the bottom end. - Nick at Pelican Parts  
DDS Comments: Dear Pelicans?thank you for this article!

Could you please share carrera s 997 3.8 engine torque specs or send it to my email



thank you!
October 4, 2013
  Followup from the Pelican Staff: Unfortunately this information is only available from Porsche at the moment in a factory repair manual. - Nick at Pelican Parts  

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