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Pelican Technical Article:

911 Engine Teardown

Time:

16 hr

Tab:

$0

Talent:

****

Tools:

Cam shaft removal tool, cam shaft holder, snap ring pliers, heat exchanger removal tool, head stud removal tool

Applicable Models:

Porsche 911 (1965-89)
Porsche 930 Turbo (1976-89)

Hot Tip:

Take pictures while you work in case you forget where something goes on reassembly

Performance Gain:

Knowledge of how the engine works

Complementary Modification:

Engine Rebuild
101 Projects for Your Porsche 911

This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.

One of the best ways to learn about how an engine works is to tear one apart. In most cases, doing so is educational, and you usually don't have to worry about breaking anything since the motor will be rebuilt anyways. It's probably a good idea to start with a core motor that desperately needs a rebuild. Having worn valve guides or rings that no longer seat are two examples of signs that a rebuild is forthcoming, and that it's probably a good time to tear down your engine.

The first step is to remove the engine from the car. For complete details on this procedure, see Pelican Technical Article: Engine Removal. After the engine is out of the car, it's probably a wise idea to place it on an engine stand. Not only is the engine up in the air and more accessible, but you can actually flip it upside down and rotate it around as you work on it. If you don't own a good engine stand (I recommend purchasing one before you rebuild your engine), you can place it on wooden blocks, and disassemble it on the ground.

The first item to be removed is the fuel injection. If you are planning on using the injection system again, I recommend that you take notes and pictures of the whole setup before, and during disassembly. Draw vacuum hose routing diagrams, and make sure that you clearly label all the connections. Take your time doing this, and also make sure that you create clear labels that will last a long time: it might take you longer than you think to rebuild your motor. Be careful of any leftover fuel in the injection system or carburetors: this can be an unforeseen danger if there are any open flame sources or even hot halogen lamps in the near vicinity. You can also opt to remove the entire fuel injection, fan and fiberglass shroud as one complete assembly. Doing so helps to keep the hoses and fuel injection components hooked up properly.

After you get the fuel injection removed and labeled, it's time to remove the fan, engine shroud, sheet metal, and the fan housing. For detailed information on removing the fan housing, see Pelican Technical Article: Alternator Troubleshooting and Replacement, Replacing Your Alternator. The fan shroud is screwed onto the top of the motor with a few sheet metal screws. As you remove screws and other components, it's good to label them in plastic bags for future reference. Nothing is worse than reassembling your motor, and not really being sure where everything goes.

With the fan and sheet metal removed, remove the clutch assembly and the flywheel. Refer to Project 8 for more details.

Once you have the fuel injection and fan assembly removed, it's time to tackle the long block. Start with the timing chain at the rear of the motor. Unbolt the motor mount, A/C compressor brackets, and smog pump/bracket (if so equipped) in order to gain access to the chain housings. Remove the rear chain housing covers, their associated oil lines, and unbolt the two tensioners. You won't be able to remove the chain until you split the case, but you can lift it off of the camshafts and move it out of the way.

Removing the camshaft nuts is a task that requires two specific Porsche tools, and cannot be easily done without them. First, a 46mm crows foot wrench is required to turn the nut, and a special Porsche tool P202 is required to hold the camshaft steady while you loosen it. The torque specification for this nut is 150 Nm (110 ft-lbs) so it will probably require the skills of two relatively strong people to remove it. Again, I cannot stress how difficult this would be to do without the special tools.

The next step is to remove the rocker arms from the cam towers. Carefully place each rocker arm and associated screws in a marked plastic bag indicating the cylinder number and whether it was part of an intake or exhaust valve assembly. Many expert mechanics believe that replacing the rockers and shafts in the same positions that they were removed from will reduce the likelihood that they will leak.

Once the rockers are removed, you can pull out the camshafts. After you remove the camshafts, you can then detach the chain housings. The next step is to remove the heads and the cam towers. Remove all the 8mm head stud nuts, and simply pull the cam towers and heads off of the cylinders. With the rockers are removed, you should have clear access to the nuts that hold the heads to the cam towers. Unbolt the heads and separate them from the cam towers.

Now, turn your attention to the engine case. Carefully remove the cylinders from the pistons and label them. It is important to keep all the cylinders matched with their respective pistons when you are reusing them. Each piston can be removed from the rods by removing the small circlip that holds in the wrist pin. Once the circlip is removed, use the handle end of a long screwdriver to tap out the wrist pin. Make sure that the piston doesn't fall from the engine case. Now, remove the oil cooler and the oil breather console on top of the motor.

With the pistons removed, you can now move to separate the case. There is a cover for the front of the intermediate shaft that needs to be removed prior to the case coming apart. Also make sure that you remove the engine sump plate from the bottom of the case. Be sure that you remove all fasteners from the case before attempting to open it. Work slowly and carefully - there are a lot of fasteners, including two hidden deep inside the timing chain area.

To separate the case, tap it with a rubber hammer. Don't use any sharp tools to pry the case apart: you might damage the parting line mating surface which will cause leaks later on. The case should come apart pretty easily. If not, double check to make sure that you have indeed removed all the fasteners. The left side of the case should be able to be lifted off of the right side without any major components falling out. Once the case is open, you can remove the crank and rods, the oil pump, timing chains, and the intermediate shaft.

Tearing apart your motor is a fun process, even if you are not planning to rebuild it yourself. If you keep careful inventory of your parts, you can now easily take them to your mechanic or engine machine shop in preparation for rebuilding.

Here is the starting point, now that the engine is out of the car.
Figure 1

Here is the starting point, now that the engine is out of the car. It is recommended that you use an engine stand to perform your disassembly work. This engine was disassembled on blocks of wood because all the engine stands were being used to rebuild other motors at the time. The first recommended step is to remove the fuel injection from the top of the motor. In most cases, it can be removed as a single unit, after unbolting the intake manifolds it from the top of the cylinder heads.

Here the fuel injection is removed, and the long block motor is exposed.
Figure 2

Here the fuel injection is removed, and the long block motor is exposed. This particular engine is a 1982 911SC motor, and is being torn down for a complete rebuild. Despite the fact that we will be having the heads rebuilt, it is still good practice to plug the intakes to the heads with paper towels to prevent debris from falling in there. Tackle the chain end of the motor first, removing the motor mount, chain covers, and the chain tensioners. Throughout the entire teardown process, keep careful track of all the nuts, bolts, screws, and other parts that you remove. I suggest that you use plastic bags labeled with a permanent marker in order to keep track of where all the parts came from.

Removal of the cams requires the use of two special tools, a Porsche cam holder tool, and a 46mm crowfoot wrench.
Figure 3

Removal of the cams requires the use of two special tools, a Porsche cam holder tool, and a 46mm crowfoot wrench. Both tools are absolutely necessary to remove the cams: don't try and get around using them. So much force will be needed to remove the large 46mm nut, that you will probably need an assistant, and even then it will be a difficult task.

Once the cam nut has been removed, the head studs (shown by arrow) can be loosened and the cam towers removed.
Figure 4

Once the cam nut has been removed, the head studs (shown by arrow) can be loosened and the cam towers removed. The removal of the head stud nuts require an extra long 10mm Allen head tool that can reach down into the recesses of the heads. Sometimes these nuts are heavily rusted, and are very difficult to remove. Spray some WD-40 on the difficult nuts and let them soak overnight before trying to remove them from the studs.

Once the head studs are removed, you can pull off the cam towers and the heads as a single unit.
Figure 5

Once the head studs are removed, you can pull off the cam towers and the heads as a single unit. In this photo, the cam tower is upside down, with the exhaust ports on the top. Visible on the first head is extensive oil residue in the blow-by area caused by the broken head studs.

The rocker arms can be removed by loosening up their attachment bolts in the cam towers.
Figure 6

The rocker arms can be removed by loosening up their attachment bolts in the cam towers. The rocker shafts are secured with a cap that expands when tightened, so be careful to loosen them up fully before removing them from their mounts. The heads can now be simply unbolted from the cam towers. The rocker arms and shafts need to be removed in order to reach all of the nuts that secure the heads to the cam towers.

Looking at the bank of pistons and cylinders, it is obvious why this motor is coming apart.
Figure 7

Looking at the bank of pistons and cylinders, it is obvious why this motor is coming apart. The arrows point to broken head studs. Surrounding the head studs is sludge that is left over from oil leaking out of the heads. Theoretically, there shouldn't be any oil in this area, but this motor had other problems as well. The Dilavar studs used in 1982 seemed like a good idea at the time, but the seven broken studs on this motor (five on the opposite side) tell a different story. If you are shopping for a 911SC or a 3.0L engine, insist that your mechanic remove the valve covers during the prepurchase inspection to check for broken head studs.

Slide the cylinders off of the pistons.
Figure 8

Slide the cylinders off of the pistons. Be gentle in the process, as these are very expensive to replace. It is the hope of most people that their pistons and cylinders are still in good enough condition to be reused, since new sets cost anywhere from $1500-$3000.

Remove the snap rings that hold on the pistons (shown by arrow).
Figure 9

Remove the snap rings that hold on the pistons (shown by arrow). Reach in with a small screwdriver, and pry the rings out of the pistons. If you are not planning on splitting the case, make sure that you don't drop the circlips down into the recesses of the engine. Cover the openings to the case with some plastic, because the snap rings have a tendency to fly out when they are removed.

Quite possibly the hardest step of all is the removal of the head studs.
Figure 10

Quite possibly the hardest step of all is the removal of the head studs. Installed by the factory using Loctite, these can really be difficult to remove. Using a propane torch to heat up the case always helps, as does the use of a special collet head stud removal tool. If the stud breaks off, then you may be forced to use other means to remove it from the case (see Project 95: Removing broken studs).

The final step is to separate the case.
Figure 11

The final step is to separate the case. An engine stand is especially useful in this stage. After removing all the case fasteners, the two halves should separate with a few light taps with a rubber mallet. Don't use any tools to pry the case halves apart, as you might damage the fragile mating surfaces in the center. Make sure that you double-check that you have removed all the fasteners before you start hitting the case with the mallet. The left side should be lifted off of the right side of the case.

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