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Discussion Starter #1 (Edited)
The AVCS gears on your cams play a vital role in the timing of your engine. If you have spun a bearing, your oil will be contaminated with metal. The metal laced oil will have made it's way to those AVCS gears and it could build up, possibly preventing the mechanisms inside to move freely.

Here is full description of what they do:

"DUAL AVCS (ACTIVE VALVE CONTROL SYSTEM) (FROM '08MY)

GENERAL
The dual AVCS (Active Valve Control System) changes the camshaft phase angle in relation to the camshaft sprocket to optimize valve timing of the intake and exhaust valves, improving torque in a low and medium speed range, output performance in a high speed range, emission performance, and fuel efficiency.
The ECM determines the best camshaft angle in relation to the crankshaft angle based on engine speed, vehicle speed, throttle angle, and other relevant parameters.
Under the control of the ECM, the oil flow control solenoid valve moves its spool to change the phase angle between the camshaft sprocket and camshaft successively by switching the oil path designed between the advance angle chamber and the retard angle chamber."




New AVCS gears from Subaru will be about $450+ for all four. That's a quite a bit of dough. So, you can choose to take your chances at bent valves and not clean the gears, buy brand new ones or simply clean them.



There are only a few components to each gear that can be taken apart and cleaned, so the process is rather easy. You just need to be mechanically inclined to do so, and of course, you need the right tools.



This is a "How-to" on cleaning these AVCS gears.



The tools you need:



1x Cordless Drill with an Impact function (If your drill doesn't have the impact function, you can buy an adapter at Lowes or Home Depot) (Drill not needed but will make the process much faster)
1x 3/8 Socket Adapter for the Drill
1x Company 23 Security Bit ($10 from Rallysportdirect)
1x Phillips Drill Bit (Or Screwdriver)
2x Picks
1x Angled Needle Nose Pliers
1x Small Pliers
1x Parts Cleaner (CRC brand is STRONG stuff, wear chemical resistant gloves and glasses for your own good!)
1x Container with Soapy Water
1x Container with Clean Water
1x Plastic Cup (NO FOAM CUPS!)
1x Paper or Plastic Plate (NO FOAM PLATES!)
1x Engine Oil (In a condiment bootle works best)
2x New OEM O-Rings #806939040
1x Torque Wrench (20-200in lbs)
1x Extra Pair of Hands (This will come in handy at the end)

You also would need compressed air and an air nozzle to dry out the components really fast, but letting them dry normally for a while is also an option.



Work on each AVCS individually from start to finish. There are two types of AVCS you will encounter. The Intake AVCS has 3 screws on the front and can be completely torn apart for cleaning, the Exhaust AVCS has a spring on the front, under the cover with the 4 screws. I will show how to clean the Exhaust AVCS when I edit this post.

WARNING: Subaru does NOT sell the components for the AVCS other than the O-rings. If you LOSE something, you will have to buy a new AVCS, so keep track of everything…


Note that you can easily identify the Driver side AVCS because the AVCS is mounted INSIDE the gears. The Passenger AVCS are mounted on the OUTSIDE of the gears. The Intake AVCS has a front cover with THREE screws and Exhaust AVCS has a cover with FOUR screws and a Spring inside it.



1.
Locate the torx bolts on the back of the AVCS gear and remove all. Separate the gear from the AVCS and set it aside. Locate the slit on the side of the AVCS where the red arrow is pointing in the picture and insert a pick between the spaces and gently pry open the back cover. Set aside the back cover (The oddly shaped o-ring should be stuck to the cover, separate carefully and set it aside. Remove the 3 screws on the front of the AVCS, set the cover aside and discard the small o-ring. Push the center piece outwards until it starts to move out the back. Be careful, as there will be 6 small springs and 6 small retainers: DO NOT LOSE THEM!




2.
Once you have everything separated, fill the small plastic cup with a small amount of cleaner solvent and put the springs and retainers in the cleaner. Swirl it around for 10 seconds and remove each piece with the small pliers. Set them aside to dry. WEAR GLOVES: Place each component in the paper plate and start cleaning. You can dump the solvent from the plastic cup on the piece. Clean each component thoroughly as there are oil passages.
Note: After cleaning each component, rinse them in the soapy water first then the clean water. Dry them out with compressed air if you have it and set aside. When you're done cleaning it will look like the picture below. (Sorry for shitty picture!)



3.
When you are done cleaning and once dried, take the piece with the three lobes and locate the lobe with the small piston-like part pictured below. Insert that piece in the circle first, and then slide it in the slot where the arrow is pointing. If you don't do this, you may place the piece in awkwardly and it may become stuck, possibly damaging the mating surfaces. You did it right when the lobed component sits flush with the housing.



4.
Place the spring in the retainer like in the picture below.



5.
There will be 6 slots to insert the springs. When all the springs are in, PRIME the AVCS with fresh engine oil. Fill the large spaces about half way. Clean the awkward looking oil seal with a paper towel or rag and place it back in it's designated position (It only goes in one way)



6.
The AVCS housing has a dowel pin, so you can't put the back cover on the wrong way. Just locate the small hole on the back cover next to the larger hole.



7.
Place the gear back in the way it came off. Again, it can only go in one way. Insert the torx bolts back in and tighten them down. Use that extra pair of hands to hold down the gears and torque the SMALL bolts to 45in lbs. Torque the LARGE bolts to 180in lbs. When you're finished with that, turn the AVCS over, insert the NEW OEM O-ring and put the front cover back on tightly and VOILA, you're DONE!

Just repeat each step for the other gear.

Now go have a celebratory beer!


REMEMBER to lube up the mating surface where the camshaft will go in!


Now to the Exhaust AVCS:

1.
The process is the same as the Intake. Start tearing down the front cover but DO NOT discard the big O-Ring, clean it and reuse it when you put everything back on. I couldn't find a way to separate the the lobed component from the housing, and since I didn't want to damage anything, I left it alone. When you take the front cover off you will notice there is a spring in the center, which is held on at two points. Use the Pick tool and pry out the spring at the top section.

Note: This spring was rather difficult to put back on. If you don't feel safe in taking out this spring, then DON'T. Skip all following steps and just simply clean everything as best as you can and put everything back on when you're done. Follow the same torque specs as the Intake AVCS. I only did it to be thorough with the cleaning. If you want to remove the spring, then read on!



2.
Once the spring is removed, you will see a thin metal shim sitting at the bottom. Don't try to shake it out. It won't come out on it's own, trust me... This is where the two picks come into play. Locate the small space in shown in the red circle and gently insert a pick in that space until you have a firm hold on it. If you can't find it, move the shim around until you do. With the pick firmly inserted, begin to lift up until you see the other side of the shim start to rise, and once that happens, place a pick under the shim and simply lift up and remove it. My apologies for not taking a picture of this process, it's kind of hard to do when you're by yourself :(



3.
When you have everything apart, spray everything with solvent, making sure everything is squeaky clean then dip each component in the soapy water, then in the clean water. Dry it with compressed air if you have it. Remember that you can't separate the lobed piece from the housing so don't try it or you may break something. Just clean it as it is. When you're done, it should look like the picture below.



4.
Assemble the front first, where the spring was. Put a little oil in the space where the shim will go back in and then place the shim back on top of the oiled surface. To put the spring back in, the easiest way to do it was to hook the top part of the spring on first, then take the Angled Needle Nose Pliers and hold the bottom part of the spring, then use the strength of a Norse god to wind the spring back to it's original location. This may take a few tries. When you're done it will look just like the picture below.



5.
Put the O-ring back on, then the front cover and tighten all four screws firmly. Flip it over and put the awkward looking O-ring back on in it's designated position. Remember to PRIME with oil just like before. Locate the dowel pin on the housing, then take the back cover and put it back on. Take the gear and put it back on top, then take the torx bolts and tighten them down. Toque the SMALL bolts to 45in lbs. Torque the LARGE bolts to 180in lbs. BOOM. You're done!




Once you're done, do the same for the other gear.

Make sure you have a celebratory beer after each completed AVCS cleaning. (If you're too young to drink alcohol, go have a soda)


Again, make sure to lube up the mating surface where the camshaft will go in!


 

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I did this during my rebuild, and i believe it was you who recommended it and walked me through the process. Nice write up, and highly recommend it. Although, I believe you meant INCH pounds, not Ft lbs of torque for the small and large bolts at the end..right?
 

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Haha I could just imagine watching someone with a huge half inch drive torque wrench trying to get 180 foot lbs on that little bolt.:lol:
 

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Discussion Starter #5
I think once you're in foot pounds with torque wrenches, you' dealing with 1 inch drives... which are used for airplanes and heavy vehicles lol.
 

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Nah, I have two half inch drive torque wrenches that I use for a lot of stuff. But thats besides the point haha. Nice write up.
 

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DAVCS rebuild, another take on rebuilding AVCS sprockets

I have just finished rebuilding two sets of DAVCS cam sprockets. I think I can add some useful informtion to what has already been presented. This video by Outback Motorsports is helpful. I have a lathe so I was able to make an alignment mandrel tool. This alignment step is important! I also took a cam and plugged two of the four feed holes and made a tapered nipple for my air gun that fits into the holes in the cam. By lightly tightening the cam to the sprocket I was then able to apply air through the camshaft, into the sprocket assembly and test its functionality and measure how much pressure was required for actuation. I'd say this process is slightly flawed since I'm dealing with air and a partially lubricated assembly, but it is better than nothing. Using oil for testing would be ideal, but very messy and complicated.

I am going to now back up to the disassembly process to start my "treatise". I kept the three outer seals separate from the inner seals as they rub on surfaces with different radii, so their faces have a different curvature once worn in. Also, the seals have ends that are different. What I've seen is that the solid end is facing out, though I can't see why it matters.
As I've been into quite a few of these used assemblies now, what I found is that all the seal's faces have some degree of scoring. For those where I felt the scoring and wear was significant I carefully smoothed the seals with 600 grit wet or dry sandpaper on a piece of very precision ground tool stock and worked on the aluminum some too using a small, flat piece of urethane that has a tiny bit of softness to it so it can conform a bit to the radius. I used a magnifying glass and/or a jeweler's eye-loupe to monitor this process. I have now tried using (by hand) a small, three-footed brake cylinder hone (much like this Lisle one) on the housing faces and I think it shows promise. I have ordered some Cratex sticks in fine and extra-fine to bond to the honing tool's shoes and I'll make them 22mm long. The cylinder hone I have is nearly perfect for this application; the "feet" are 23mm long and the tool will expand out to the larger diameter. "Stones" or Cratex blocks can also be used individually. The nice thing is, the foot attached to the honing tool's leg allows you to evenly distribute the pressure on the surface to help prevent rounding, gouging and uneven material removal.
I usually found some gouging of the inside of the steel cover/cam attachment plate. This is caused by abrasion from the flat face of the rotor's lobes as it wipes back and forth. Sometimes some etching occurs from corrosion and sometimes some cupping of the steel face is evident, so I lap that inside surface smooth and flat, on a flat plate, using #320, then #400 grit wet or dry with water or oil.
You can also do a little smoothing on the rotors, as they can get rough out toward the edges. I if you take off very much you can compensate by lapping the housing's outer face the same amount (after pulling out the alignment pin).
Clearance of the rotor's thickness to the body depth seems to be zero! I measured parts and saw little or no difference in size! I mean, less than one thousandth of an inch. So parts need to be smooth! I can only assume that irregularities and possibly internal pressure creates enough space for the rotor to move. After assembly, my rotors/cams moved when I used 80 psi of air or less.
I think cleanliness is extremely important. These can be very nasty internally from wear and trapped particles. I used Gunk degreaser concentrate in kerosene and had two rinses. I then blew everything off.
I used blue Locktite on all six screws and torqued them to 88 inch pounds and 22 foot pounds, respectively. Most "cap screw" style of screws are high-strength so I used the upper end of Subaru's torque spec's for each bolt and the 22 FPT was what it felt like it took to loosen the big 8mm bolts. Also, there is a lot of thread engagement.
As a note, I found that four of the six units (with the big springs in them) had the 2.5mm pin sheared. This was likely due to assembly or disassembly of the sprockets from the cams by clamping the camshaft or because of a catastrophic failure in the valve-train. It is absolutely a no-no to use Vice-Grips or the like to keep the cam from rotating while loosening or tightening the 12mm sprocket to cam bolt.
I cannot find a source for the odd-shaped seal. It and the o-rings were often fine for re-use but sometimes they were permanently flattened and useless. If I had to use a hard, old seal I would clean everything well with acetone and use black silicone sealant around the seal. O-rings, on the other hand, are easy to come by.
I purchased the five-point bit from Company 23. Even after I ground down the 3/8" socket holding the bit it could not engage straight into the smaller bolts on the deep, right-hand sprockets. I used a torque wrench religiously, yet after about 150 uses it snapped off, right where the hole in the middle ended. I really thought that the Company 23 bit would not have a hole in the middle, but I was wrong. With the use of my lathe and a Dremel I reground the nub and got it working again.
Note: I have since upgraded the bolts to all socket-head cap screws from McMaster-Carr and the "FU" hex-head cam bolts by TIC.
 

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I've been following your thread then just came across the alignment tool comment. When you cleaned yours for the write up did you have any issues from not using the alignment tool? I felt like I had it conquered and now I can feel the slight bit of difference between the top plate and bottom plate where the camshaft inserts.
 

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At a minimum, you need a cam stuck in there to keep the parts aligned during assembly! The cam end is smaller than the hole (so that it is an easy slip fit) so you can still get slight misalignment when you start bolting it back together. If you can't get a simple pin turned by a machine shop then I suggest you get an old cam and cut off the end. You can probably score it or dimple it in three or more places to create, in effect, a larger diameter. If you try and eyeball it or just use a cam shaft, you could have an interference fit such that it abrades the aluminum going in, scrapes off aluminum or is off-center enough that the rotor drags or sticks.

Incidentally, while on the dyno, the tuner commented that the rebuilt AVCS units in my engine were some of the most responsive he had ever seen.
 

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Discussion Starter #11
I didn't have issues at all. Tuned twice on rebuilt cam gears with no problems so far. The dowel pin will hold the plate in place but I made sure to align the plate as best I could before torquing down. Also as mentioned above, I used a little bit of locktite as well.
 

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... The dowel pin will hold the plate in place but I made sure to align the plate as best I could before torquing down...
I was not referring to the aluminum housing to steel cover fit or alignment but to the relationship of the internal three-lobed rotor to steel cover plate. This is where a mandrel or cam needs to be inserted to center and place the rotor in alignment before you start torquing things down.
As I mentioned, the video by Outback Motorsports is helpful.
 

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I just bought new Cam Gears from Subaru. June 2018, the exhaust Cam Gears DO NOT have the shim plate behind the springs. Something new? Any way I have to open and clean them out. Spun a rod bearing.
 

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I have to make an alignment tool :naughty:
Alignment mandrel is easy. What year/part number AVCS cam gear assembly did you buy?
I have rebuilt quite a few. I upgrade the screws to standard Allen cap screws from McMaster-Carr..
 

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Alignment mandrel is easy. What year/part number AVCS cam gear assembly did you buy?
I have rebuilt quite a few. I upgrade the screws to standard Allen cap screws from McMaster-Carr..

SPROCKET ASSEMBLY-CAMSHAFT INTAKE RIGHT
Part Number: 13320AA001

SPROCKET ASSEMBLY-CAMSHAFT EXHAUST,RIGHT
Part Number: 13321AA001

SPROCKET ASSEMBLY-CAMSHAFT INTAKE LEFT
Part Number: 13322AA001

SPROCKET ASSEMBLY-CAMSHAFT EXHAUST,LEFT
Part Number: 13323AA001

Also seems the pin on the internal rotor is bent on one. I thinking Company 23 cam holder tool is to blame:

502-4.jpg
 

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Also seems the pin on the internal rotor is bent on one. I thinking Company 23 cam holder tool is to blame:
Those are the standard numbers. I cannot look at my parts at the moment.
The Company 23 tool is expressly designed to prevent crunching the pin. You should hold it rigidly and not let it rotate when you remove those mother f* bolts though.
Are you the first to remove the AVCS cam sprockets? I have seen some really bad advice about how you can keep the cam from turning and then break loose the bolt. That puts all the torque on the pin. Also, if you pinch the belt and use it to restrain the sprockets there is some risk of touching a valve and doing damage if you get it wrong. It may be that a piston hit a valve at some point.
 

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Those are the standard numbers. I cannot look at my parts at the moment.
The Company 23 tool is expressly designed to prevent crunching the pin. You should hold it rigidly and not let it rotate when you remove those mother f* bolts though.
Are you the first to remove the AVCS cam sprockets? I have seen some really bad advice about how you can keep the cam from turning and then break loose the bolt. That puts all the torque on the pin. Also, if you pinch the belt and use it to restrain the sprockets there is some risk of touching a valve and doing damage if you get it wrong. It may be that a piston hit a valve at some point.
Not the pin on the cam. The little tiny pin inside the exhaust avcs . One pin is sheared off. See video here: STI EHAUST AVCS - YouTube

You can get a cheap 499977500 tool here: Amazon.com: CTA Tools 7615 Camshaft Holder (Subaru): Automotive
 

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Discussion Starter #19
I didn't have that pin when I popped my gears open. I also could not remove that center section that you were handling in the video. I looked like it was permanently attached to the main body of the gear to me. What year and model Subaru are you working on? Mine is an 08' STI
 

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I didn't have that pin when I popped my gears open. I also could not remove that center section that you were handling in the video. I looked like it was permanently attached to the main body of the gear to me. What year and model Subaru are you working on? Mine is an 08' STI
They are not permanently attached and if your pin is bent that would make it really hard to come off. If you do not have pins then the center hub I was handling in video would be allowed to rotate when tightening or removing the cam bolt. That center hub rotates with the internal rotor and the cam shaft (the cam bolt is holding the center hub, the inernal rotor and the cam shaft all in alignment. The spring is there to help it rotate in one direction. The Spring that wraps around that hub is important so the hub must be held in alignment with the internal rotor, that is why Subaru put a pin there. The Pin is just for alignment purposes and is to small to handle any amount of torque. But when you hold the outer body of the AVCS with the Company23 tool and then try and tighten or even worse loosen the cam bolt the pin can not handle that. These are the exhaust only cam sprockets. You can look thought to hole in the center hub and see if pin is there if it is not you prolly sheared it off already or it is bent making to seem impossible to come off. 2010 STI and the cam gears I am showing is 1 from 2010 (the sheared one) and the one with the pin intact is from a cam gear I just bought june 2018 from Subaru brand new. So the Pin is in both the 2010 and present date.

My answer is to use the tool 499977500 that Subaru recommends and not the Company23 Tools. You can get a cheap one here: Amazon.com: CTA Tools 7615 Camshaft Holder (Subaru): Automotive

I do not make any profit from the tool I am pushing. In fact it was your Post about how to clean the AVCS that got me taking them apart in the first place.
 
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