Pelican Technical Article: Camshaft Upgrade / Chain Tensioner Replacement Wayne R. Dempsey
Time: 10 hrs
Tab: $100-$2500
Talent:
Tools:
Camshaft timing tool, crankshaft locking tool
Applicable Models:
986 Boxster (1997-04) 987 Boxster (2005-08)
Parts Required:
New camshafts, 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 article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
This project started out as a simple addendum to checking the camshaft timing when performing the intermediate shaft bearing replacement (see Pelican Technical Article: Intermediate Shaft Bearing Replacement and Upgrade (IMS)). 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 projects covers the following tasks or potential problem areas you might encounter on your Boxster 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 core motor that I purchased for demonstration purposes: it had been involved in a car that had 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 the link at the top of this project.
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.
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 (5/16th 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 crankshaft from behind the seats (see Pelican Technical Article: Drive Belt Replacement).
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 and the part number is 996-104-215-54.
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 Photo 3 of Pelican Technical Article: Boxster Engine Teardown), 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% absolutely necessary. This is one of those cases: use the P253 tool instead.
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. 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. 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 Boxsters / Caymans) that seal them to the cylinder head and camshaft cover.
Shown here is the solenoid that activates the valve which 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.
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 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.
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). 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. This is an example of a camshaft bearing that is scratched and becoming worn. If this were on a 1965-89 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 need to basically 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 Boxster motor. The one shown here tensions the chain for cylinders 4-6, 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: Intermediate Shaft Bearing Replacement and Upgrade (IMS)).
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 amongst them. A- The chain tensioner for cylinders 4-6 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 left 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: 900-123-147-30) and the small o-ring on the tensioner shaft (purple arrow, PN: 999-707-344-40).
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. 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 onto 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. 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. 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. 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: 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 Figure 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. 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. 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. Sitting in the backseat of the Boxster, 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. 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. 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.
Comments: Great site thanks! I own a Boxster S 2002 and have an oil leak from one Tensioner. Can I just unscrew remove it & replace the two washers and screw it back in?
March 6, 2012
Moose
Comments: I have a 2001 Porsche Boxster with 92k miles. I have a leak in the valve cover on the passenger side. I wanted to do the job myself due to labor cost. The runs great! What should I replace when I install new sealant? I purchased the new spark plug tubes and seals, new plugs, using loctite 5900 flange sealant. Should I replace anything else when the cover is off and should I do both sides. I'm not an experienced mechanic and not even sure I should do it myself. I just bought your 101 project book which is awesome to say the least. I just wanted to save on labor costs, but I do not want to mess it up? Any advice Wayne?
February 22, 2012
JW Auto Tec
Comments: Is there enough room for the spark plug tubes to pull out with the cam shaft cover with the engine in the vehicle? JW
January 20, 2012
Followup from the Pelican Staff: Sure, should not be a problem. You might want to use some right-angle, large needle-nose pliers to assist you. - Wayne at Pelican Parts
paradigm
Comments: I have a 07 Cayman S and intend to remove the valve covers to inspect for damage. Dealership believes I may have a broken valve spring based on the irregular tapping noise at idle a heavier sound than what I would call a tick, or possibly a stretched chain flapping around. Using PIWIS the cam timing was fine and we found absolutely no debris in oil filter we cut open had 3500 miles on the oil and I'm using the LN spin-on.
In any case, I intend to do this with the motor still in the car is access in the cayman better than the boxster? and reading through this article in conjunction with Project 14 it doesn't look too bad. However I must have a 3-chain engine and I can't find the procedure you reference as being available through a link at the top. I only find a link for the main 101 Projects page. In particular I'm curious about how the variable valve actuator, etc. is situated. Can you help?
Thanks for providing so much useful information, it would so much harder for the DIY crowd without it.
January 1, 2012
Followup from the Pelican Staff: Sorry about that - we're working on the 996 book right now, and the 3-chain motor teardown / retime will be released in conjunction with that. I haven't had the time just yet to tear down the 3-chain motor that I have acquired for this. I'll copy this to the forums, and perhaps someone there will have some additional suggestions. - Wayne at Pelican Parts
spudsmack
Comments: I have a 2000 Porsche Boxter. I had the 75K service done and there were plastic shavings on my oil filter. I was told the plastic was from the chain ramps. Can these ramps be replaced? A local import garage said I needed a new engine, that the ramps were not serviceable. The car currently runs great.
June 6, 2011
Followup from the Pelican Staff: The chain ramps are replaceable, but only if you take the engine apart, which you probably don't want to do. I would probably run a slightly thicker oil in the engine, and change the oil religiously every 3,000 miles to prolong it's life from this point on. Other than that, I'm not sure what else you can do? - Wayne at Pelican Parts
Check out some other sample projects from the book:
