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Porsche 911 Carrera Camshaft Swap and Valve Train Repair
 
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Pelican Technical Article:

Porsche 911 Carrera Camshaft Swap and Valve Train Repair

Time:

10 hours10 hrs

Tab:

$100 to $2,500

Talent:

*****

Tools:

Camshaft timing tool, crankshaft locking tool

Applicable Models:

Porsche 996 Carrera (1999-05)
Porsche 996 Carrera 4 (1999-04)
Porsche 996 Carrera 4S (2002-05)
Porsche 997 Carrera (2005-08)
Porsche 997 Carrera 4 (2006-08)
Porsche 997 Carrera 4S (2006-08)
Porsche 997 Carrera S (2005-08)

Parts Required:

New lifters, solenoid, etc.

Hot Tip:

All of these tasks should be able to be done with the engine in the car, but are far easier with the engine removed

Performance Gain:

More horsepower

Complementary Modification:

Replace intermediate shaft bearing

This project started out as a simple addendum to checking the camshaft timing when performing the intermediate shaft bearing replacement (see Pelican Technical Article: IMS Bearing Replacement - Porsche 911 Carrera). However, after further consideration, I decided to expand it to include all of the items in your valvetrain that you might have problems with in the future. Specifically, this project covers the following tasks or potential problem areas you might encounter on your Carrera engine:

  • Fixing camshaft cover leaks
  • Replacing the VarioCam solenoid
  • Swapping out your camshafts
  • Checking the camshaft timing
  • Replacing noisy lifters (tappets)
  • Replacing the external chain tensioners
  • Replacing the internal cam-to-cam chain tensioner
  • Replacing chain ramps

For the purpose of illustration, the motor used in this project was out of the car on an engine stand. It's an old Boxster core motor that I purchased for demonstration purposes-it had been involved in a bad fire. The core motor is fine, but all of the injection and sensors were destroyed in the fire-perfect for rebuilding or for photos! This motor is a five-chain engine, which is significantly different than the later-style three-chain engines. See Project 14 for a description of the two types and how to tell the difference between the two. For those of you who have a three-chain engine, the procedures documented here are available on the official website for this book, refer to http://www.101projects.com/Carrera/16.htm

All of the tasks illustrated here should be able to be performed on the engine while still installed in the car, although clearance is tight and it's somewhat difficult to work under the car. I've broken the tasks up into photo captions-read along for the procedures detailing the tasks listed above.

Disassembly: The first step in this whole process is to set the crankshaft to Top Dead Center (TDC) and lock it there.
Figure 1

Disassembly: The first step in this whole process is to set the crankshaft to Top Dead Center (TDC) and lock it there. Turn the engine until the tear dropped-shaped hole lines up with the hole in the case. Insert the way-overpriced factory knob in place, or simply use a punch or an appropriately sized drill bit (5/16 size worked well for me). Set the crankshaft at TDC right now-the camshafts rotate at one-half the speed of the crankshaft, so the crankshaft is located either at TDC for cylinder 1 or TDC for cylinder 4. If need be in the next few steps, you might have to rotate it another 360 degrees if it's not at TDC for the cylinder bank you're working on. If you're performing these tasks with the engine in the car, then you need to access the rear of the engine. You will need to remove the air box (see Pelican Technical Article: Porsche 911 Carrera Engine Drop) to gain access. Since you will be removing the plugs any ways go ahead and pull them first, as this will make attempting to rotate the engine by hand easier.

Now remove the two cam plugs that sit on the end of the two camshafts.
Figure 2

Now remove the two cam plugs that sit on the end of the two camshafts. You need to remove these green plugs to inspect/check the timing when performing the intermediate shaft upgrade. You basically poke a hole in the center of the shaft and then pull it out. Toss the old ones away, as you will not be reusing them. The engine uses a total of three per head.

With the plugs removed, now install the camshaft timing tool, P253 onto the end of the camshaft.
Figure 3

With the plugs removed, now install the camshaft timing tool, P253 onto the end of the camshaft. Normally, you would use Porsche tool 9624 to hold the camshafts onto the end of the motor (see Figure 3 of Pelican Technical Article: Porsche 911 Carrera Engine Tear Down), but I found that the camshaft timing tool also pretty much did an adequate job of holding them in place as well. While I personally have most of the tools listed as required in the Porsche factory manuals, I like to try to recommend places where they may not be 100 percent absolutely necessary. This is one of those cases-use the P253 tool instead.

Remove the oil pump from the cylinder head.
Figure 4

Remove the oil pump from the cylinder head. It's a wise idea to get a marking pen and mark the pump where it lines up with the engine case-it can be installed backwards by mistake. Remove the four bolts that hold the pump to the case (orange arrows), not the four Allen screws that are internal to the pump. Use two pry bars to simply pull the pump out of the end of the engine.

With the oil pump removed, remove all of the perimeter bolts from the camshaft cover.
Figure 5

With the oil pump removed, remove all of the perimeter bolts from the camshaft cover. Also remove the two bolts that hold on the cover for the VarioCam solenoid (green arrow, lower right). With everything disconnected, use a few pry bars on the separation areas of the case and the cylinder head (yellow and red arrows) to pry the camshaft cover off of the head.

When you remove the camshaft cover, you should see the camshafts and the chains underneath.
Figure 6

When you remove the camshaft cover, you should see the camshafts and the chains underneath. The top camshaft will want to move outwards when you remove the cover, but the force of the camshaft timing tool against its end should keep it relatively secured. It's okay if it pushes out by a few millimeters. I have heard from various sources that the camshaft can snap if there is enough force placed on it from the valve springs, so make sure that it doesn't move significantly out of its bore. The yellow arrow points to the spark plug tubes (found on early engines). Now would be a good time to replace them and the O-rings (found on all 2005 and later 997 cars) that seal them to the cylinder head and camshaft cover.

Shown here is the solenoid that activates the valve that turns on the hydraulic oil pressure supply that advances the camshafts for the VarioCam operation.
Figure 7

Shown here is the solenoid that activates the valve that turns on the hydraulic oil pressure supply that advances the camshafts for the VarioCam operation. This solenoid has a habit of failing and needing replacement. Once you have the camshaft covers off, replacement is a snap. Simply unscrew the old one and install the new one in its place. At about $200 apiece, they are probably the world's most expensive solenoids.

Now, loosen and detach the camshaft sprocket from the exhaust camshaft.
Figure 8

Now, loosen and detach the camshaft sprocket from the exhaust camshaft. Four small bolts hold it on to the camshaft.

Carefully remove the leftmost camshaft-bearing caps on both of the camshafts (green arrow, inset photo).
Figure 9

Carefully remove the leftmost camshaft-bearing caps on both of the camshafts (green arrow, inset photo). Then remove the three very long bolts that secure the VarioCam chain tensioner to the cylinder head.

Now, loosen up the chain tensioner on the head (refer to Photo 16 for cylinders 1-3
Figure 10

Now, loosen up the chain tensioner on the head (refer to Photo 16 for cylinders 1-3 or Photo 17 for cylinders 4-6). With the chain tensioner loosened, the bearing caps removed, and the VarioCam tensioner disconnected from the head, you should be able to slide the gear off of the camshaft with your hand. A few gentle taps with a small rubber hammer can also help your cause if it's stuck. Let it sit next to the camshaft in the case. If you are performing this procedure with the engine in the car, be aware that once you remove the cam gear, the camshafts may slide out of the head-be ready to catch it. If you are performing this task on an engine stand, then simply rotate the engine at an angle, so that the camshafts won't fall out.

With everything disconnected, remove the camshaft timing tool from the engine.
Figure 11

With everything disconnected, remove the camshaft timing tool from the engine. Remove the camshafts and move them over to your workbench.

Shown here are the two camshafts, the small timing chain, and the VarioCam tensioner that ties them together.
Figure 12

Shown here are the two camshafts, the small timing chain, and the VarioCam tensioner that ties them together. There is a special tool that is used to compress the tensioner together to make it easy to remove, but I just opted to use a zip tie instead. Works great, and when you're ready to expand it again, you just clip the zip tie.

With the camshafts removed, you can simply pluck out the lifters (tappets).
Figure 13

With the camshafts removed, you can simply pluck out the lifters (tappets). Check both the lifters and the lifter guides for damage (pockets of wear greater than 1mm, fractures at the edges, irregular contact patterns on the running surfaces, grooves in the oil pockets for the cam lobes). Clean each lifter carefully with a lint-free cloth. I recommend using KimWipes, which I used all the time in the past when I was working in clean rooms building satellites. You can find these at PelicanParts.com--they are perfect for cleaning intricate engine parts where you don't want paper fibers or debris contaminating tiny oil passages. With the lifter clean, dip it in some fresh motor oil. Use whatever motor oil you're planning on using when you refill the car. Press down on the inside of the lifter while it's submerged so that you can clean out the internal passages as best as possible. It's particularly important to clean everything if your engine had its oil contaminated with coolant. Failure to clean and lubricate thoroughly may result in what is known as a noisy lifter-one that doesn't completely engage. This can lead to degradation in engine performance. The Porsche factory manuals recommend not using a magnet to pluck the lifters from their bores (use your fingers or a mini-suction-cup device instead).

This is one of the reasons why I don't care for Porsche's recommendation of going 15,000 miles between oil changes.
Figure 14

This is one of the reasons why I don't care for Porsche's recommendation of going 15,000 miles between oil changes. This is an example of a camshaft bearing that is scratched and becoming worn. If this were on a 1965-1989 Porsche 911 engine, I would recommend replacing the bearing. However, the camshaft cover and cylinder head are matched pieces, and to replace this bearing, you basically need to replace the entire cylinder head! It's not worth the risk-change your oil every 3,000 to 5,000 miles with an oil that has a high level of anti-wear additives and keep bearing wear to a minimum.

There are three externally accessible chain tensioners on the motor.
Figure 15

There are three externally accessible chain tensioners on the motor. The one shown here tensions the chain for cylinders Picture 6:, and is by far the most difficult to reach. It's located underneath the air conditioning compressor, inside the cylinder head, and is accessible from inside the engine compartment. In order to loosen this tensioner, you need to remove the two screws that hold on the air conditioning compressor and nudge it out of the way. Then use a 32mm socket to loosen the tensioner as shown in the inset photo in the lower right. You loosen the tensioner in order to replace the intermediate shaft bearing (see Pelican Technical Article: IMS Bearing Replacement - Porsche 911 Carrera).

This photo shows the chain tensioner for cylinders 1-3
Figure 16

This photo shows the chain tensioner for cylinders 1-3, which is located inside the bottom of the cylinder head. The three tensioners are all different, but look remarkably similar. Porsche marked the top of each tensioner with different rings in order to help distinguish among them. A The chain tensioner for cylinders Picture 6: located under the air conditioning compressor. B: The main intermediate shaft tensioner, which fits inside the crankcase near the flywheel. C: The chain tensioner for cylinders 1-3, which fits into the bottom of the cylinder head. Note the handy marking on the head itself (purple arrow).

This photo shows the tensioner for the chain that runs between the crankshaft and the intermediate shaft,, which is located on the right side of the engine case very close to the bottom of the flywheel.
Figure 17

This photo shows the tensioner for the chain that runs between the crankshaft and the intermediate shaft,, which is located on the right side of the engine case very close to the bottom of the flywheel. When replacing the intermediate shaft bearing, loosen the tensioner as shown in the inset photo. If the tensioners are leaking, you should replace the metal sealing ring (orange arrow, PN: Picture 123:-Picture 30:) and the small O-ring on the tensioner shaft (purple arrow, PN: Picture 707:-Picture 40:).

Reassembly: Begin the process of reassembly by taking the two camshafts and lining them up on your bench.
Figure 18

Reassembly: Begin the process of reassembly by taking the two camshafts and lining them up on your bench. The cam-to-cam chain has two special links that are colored differently (green arrows). Align these links up with the divots that are located on each camshaft (yellow arrow). Keeping these two links lined up with the divots will keep the two camshafts timed with respect to each other.

Using care not to let the chain slip on the camshaft gears, install the tensioner in between the two sprockets.
Figure 19

Using care not to let the chain slip on the camshaft gears, install the tensioner in between the two sprockets. It's also a good time to replace your chain ramps if they appear worn (inset photo, lower right-they simply snap off). You will have to maneuver the tensioner and the camshafts back and forth to get the tensioner in there. Once installed, clip the zip tie and expand the tensioner-this should secure the chain, and the camshafts should be securely timed with respect to each other. Before going on to the next step, you should meticulously clean all of the mating surfaces of both the cylinder head and the camshaft cover (red arrows, inset photo) with gasket remover and a sharp razor blade. Remove all traces of sealant from both surfaces.

With all of the sealant material cleaned from the cylinder head, lay the camshaft assembly down into the cylinder head.
Figure 20

With all of the sealant material cleaned from the cylinder head, lay the camshaft assembly down into the cylinder head. Double-check that the light-colored chain links and the divots in the camshafts are still lined up properly. On the opposite side of the cylinder head, the lower camshaft should line up with the cylinder head/cover parting line, as shown in the inset photo.

Using your left hand, push the camshaft into place while affixing the camshaft bearing cap into place.
Figure 21

Using your left hand, push the camshaft into place while affixing the camshaft bearing cap into place. Tighten down the bearing caps and also tighten down the tensioner housing. It's important to keep in mind that the German word for intake is "einlass," which starts with the letter E, and the word for exhaust is "auspuff," which starts with the letter A: E = intake, A = exhaust. The cylinder head, the camshaft cover, and these two little caps are all machined together and are labeled with the same number so that they won't be mixed up during the assembly process. Since the camshaft cover is machined and matched with the cylinder head, the cover is not available from Porsche as a separate, orderable part number. You must order a complete new cylinder head, which will include the head, the cover, and the caps all matched together. This makes rebuilding and repairing any damage due to camshaft bearing wear very difficult.

With the camshaft caps in place and the tensioner tightened down, affix the camshaft timing tool to the opposite end.
Figure 22

With the camshaft caps in place and the tensioner tightened down, affix the camshaft timing tool to the opposite end. There are a set of Porsche tools that are used to hold the camshaft in place while working on the engine at this stage. I found them unnecessary as the camshafts are held in place if you install the timing tool as shown.

Remove the chain tensioner for that bank
Figure 23

Remove the chain tensioner for that bank--shown here is the tensioner for cylinder bank 1-3 (green arrow). With the tensioner removed, you should have enough slack to push on the chain sprocket (purple arrow) with your hand. Gently tap the sprocket on the rest of the way using a rubber mallet (inset photo). If you have the Porsche factory chain tensioner tool 9599, then install it into the bottom of the case. Tighten the tension screw until the small rod in the center is flush with the adjustment screw. If you do not have this extremely expensive tool (upper right inset of Photo 24), you can tighten up the tension on the chain using the regular chain tensioner. Reinstall the tensioner completely into the bottom of the case.

With the camshafts installed, the timing tool in place, the two bearing caps tightened down, the camshaft solenoid tensioner tightened down, and the primary tensioner reinstalled in the case, tighten down the four bolts that hold the camshaft sprocket to the camshaft.
Figure 24

With the camshafts installed, the timing tool in place, the two bearing caps tightened down, the camshaft solenoid tensioner tightened down, and the primary tensioner reinstalled in the case, tighten down the four bolts that hold the camshaft sprocket to the camshaft. Double-check once again that the special colored links (green arrow) in the cam-to-cam chain are properly lined up with the divot mark in the camshaft (yellow arrow). Temporarily reinstall the camshaft cover using only a handful of bolts, lightly tightened down, and then remove the camshaft timing tool. At this point, spin the engine two full turns to recheck the camshaft timing by reinstalling the tool again. The upper right inset photo shows the very expensive Porsche chain tensioner tool in place (not required).

Next, reinstall the oil pump onto the exhaust camshaft using two of the four bolts to affix it to the cylinder head.
Figure 25

Next, reinstall the oil pump onto the exhaust camshaft using two of the four bolts to affix it to the cylinder head. Carefully line up the tab of the oil pump with the slot on the camshaft and make sure that it's inserted correctly. The two scavenge oil pumps are the same for either side, but they must be installed with the proper side facing up. There are markings for cylinders 4-6 (green arrow) and 1-3 (yellow arrow). The pump must be installed with the markings for the current cylinder bank closest to the crankcase. Standing behind the 911, looking at the engine and the crankshaft pulley, cylinders 1-3 are on the left, and 4-6 are on the right. If you get confused, the basic rule is that the two pumps are installed opposite to each other. The oil pump for 1-3 is located on the flywheel side of the engine, and the oil pump for 4-6 is located on the drive belt side of the engine.

Perform a final cleansing of the surfaces with some isopropyl alcohol and let it evaporate fully before applying the sealant.
Figure 26

Perform a final cleansing of the surfaces with some isopropyl alcohol and let it evaporate fully before applying the sealant. Porsche recommends the use of Drei Bond silicone, type 1209, or Loctite 5900 flange sealant to seal the surface area of the head to the camshaft covers. Don't forget to apply a thin bead of sealant to the bearing saddle areas in the inner part of the head as well. With the sealant applied, tighten down all of the bolts on the camshaft cover in the order shown on this diagram. Carefully tighten each bolt to 10 ft-lbs (12 Nm), which is not a lot of force.

As a final step, insert the camshaft plugs into the end of the camshafts.
Figure 27

As a final step, insert the camshaft plugs into the end of the camshafts. Lightly tap them into place with a rubber mallet. Tighten down the two remaining bolts on the oil pump and also the two bolts that secure the cover for the solenoid. With one side of the engine complete, move onto the other side and repeat the process if necessary.

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Comments and Suggestions:
Porschetech3 Comments: Just a comment to Steven, Yes the head , cover, and both cam caps will have the same matching numbers etched on them.Also the cam caps will be etched with an A or E. the A= Auspuff exhaust and E= Enlass Intake.
August 18, 2016
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Steven Comments: I bought a replacement head, but the seller didn't send the camshaft bearing caps or head cover. He apparently has them, but are mixed in with other parts. I see etched numbers on my old camshaft bearing caps. are there matching etched numbers on the head and the head cover? and if so, where are they?
-Steven
July 1, 2016
  Followup from the Pelican Staff: I am not aware of etchings. You will want to use the cover from the matching head, for the sake of the camshaft wear on the bearing surfaces. - Nick at Pelican Parts  
365dan Comments: Is it necessary to use a special tool to set the timing sprocket on the cam ?

I am rebuilding my 2001 996 and want to be sure i am doing it properly. do i need to turn 360 degrees to set timing on 4-6 bank?
Thank you in advance for any help this has been a tedious but fun rebuild i am anxious to get my motor back in and running.
October 24, 2015
  Followup from the Pelican Staff: Yes, a full 360° until cylinder 4 is at TDC. - Nick at Pelican Parts  
Pieter Comments: What is the deference between the 2,5 Boxster cylinder head and the 2001 996 3,4l cylinder head
October 3, 2014
  Followup from the Pelican Staff: I would need the VINs of the vehicles to be sure. But likely the timing chain and camshaft set up. - Nick at Pelican Parts  
Rob Comments: why is no one posting anything about 3chain 2003 0n cam allocation ?
June 27, 2014
  Followup from the Pelican Staff: Not sure. I would grab a repair manual. It will list the special tools and each step of the procedure. Give our parts specialists a call: 1-888-280-7799 They will help you find what you need.
- Nick at Pelican Parts
 

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