Servicing the Intake AVCS Gears..

[RumblyXT]

Hello everyone,

 

I am preparing things to tackle the overhaul of my ej255 motor on my '05 OBXT which has 210K miles and it is slightly overheating (unsure why yet). The temperature gauge rises past midline when driving the car hard for some time. This is my first ever Turbo Subaru.

 

About two years ago, I rebuilt an ej251 from an N/A '01 Forester SF, which I really miss.

 

I have an idea on the order of thing on what I need to do, but given I'm now dealing with a turbo motor and dual AVCS system, I might need your help on servicing these gears. I'm on a limited budget and these gears are not cheap.

 

I tried getting a better history of my car, but have not been able to contact the previous owner who mildly modified the car. It has these parts installed: (AEM SRI, Down Pipe, Grimspeed ebcs, aftermarket Intercooler and Turbo to Right AVCS oil line).

 

I searched the forum but haven't found anything in depth in regards to servicing the AVCS Gears and the FSM just mentions their function..

I want to do things right and avoid braking something.

 

1. Do I need to disassemble the Cam Gears to service them and replace their O-rings inside? Given my car's mileage, I'm concerned of them being contaminated with debris inside them, specially since one of them doesn't have the banjo bolt with the protrusion on the head indicating there is no filter inside.

 

2. What specialty tools have you guys used for them? On this YouTube video, this person bashes the Company23 tools (which have been great for me in the past), but he stated they destroy/damage the Gear's internals when removing it from the camshaft. And instead he recommends using the Subaru recommended tool.

 

 

3. Is there an O-Ring kit for the AVCS Gears? I have looked everywhere and cannot find OEM or aftermarket O-rings for them.

 

I admit I'm a bit intimidated by the way these gears work advancing/retarding timing.. Last thing I want is bent valves and catastrophic engine failure..

 

Your help/comments/suggestions will be greatly appreciated.

Edited January 4, 2022 by RumblyXT

[silverton]

the AVCS gears are not user serviceable, so there are no internal parts you can buy. You also need a special 5 point 'torx' style bit if you're really set on cleaning these. I've only had one mishap using the company 23 exhaust cam gear where the spring came unsprung.

 

https://www.iwsti.com/threads/avcs-gear-cleaning-guide-read-this-if-you-spun-a-bearing.279112/

 

If it were me, and I've done this before, if you really are concerned, buy new. It's money but it is peace of mind for how ever many dollars you've already spent on the rest of the motor, potentially half assing your AVCS gears could grenade the whole thing.

 

That being said, I would figure out why your engine is over heating before you rebuild it. You may find you do all this work and it still over heats. Done all the usual? thermostat, coolant, radiator? Just to rule it out, even if you do still have heat, bypass the heater core. I've seen that before and it blew my mind.

Edited January 4, 2022 by silverton

[RumblyXT]

the AVCS gears are not user serviceable, so there are no internal parts you can buy. You also need a special 5 point 'torx' style bit if you're really set on cleaning these. I've only had one mishap using the company 23 exhaust cam gear where the spring came unsprung.

 

https://www.iwsti.com/threads/avcs-gear-cleaning-guide-read-this-if-you-spun-a-bearing.279112/

 

If it were me, and I've done this before, if you really are concerned, buy new. It's money but it is peace of mind for how ever many dollars you've already spent on the rest of the motor, potentially half assing your ACVS gears could grenade the whole thing.

 

That being said, I would figure out why your engine is over heating before you rebuild it. You may find you do all this work and it still over heats. Done all the usual? thermostat, coolant, radiator? Just to rule it out, even if you do still have heat, bypass the heater core. I've seen that before and it blew my mind.

 

I bought the car from a mechanic who just maintained it and changed the usual maintenance parts: brakes, fluids, tires, lightbulbs, etc.. T/B was done by previous owner to him.

 

Once I remove the motor, I will replace every T/B component, Seals, Gaskets, Grommets, etc with OEM ones. I don't want to have any Chinese bearings/pulleys on my car, especially when it comes to parts as important as T/B components.

 

Funny you are mentioning bypassing the heater core system. After doing an oil change and replacing the coolant, I notice the car came with the inlet hose to the heater core clamped with pressure pliers, go figure. Not sure if that's somehow playing a part in it overheating.

 

Anyways.. I think it's BS that Subaru says these AVCS Gears are not serviceable. WE should be able to do absolutely everything on these cars. Otherwise, how do dealers service the Gears? They scrap them? That wouldn't make any sense..

 

Thank you for your reply

[RumblyXT]

I noticed on the FSM the specialty tools names required to remove the Intake & Exhaust Gears are different, not because the sprockets are different outside, but instead because the Intake gear is supposed to be removed holding the AVCS Gear from inside..

 

The FSM Intake gears specialty tool is 499977500. Looking at it, it does not hold the sprocket from outside (unlike the Company23 tool does which in fact may end up damaging the AVCS Gear inside). Instead, the Subaru OEM tool, locks the inside of the AVCS Gear inside by the cam, preventing it from being damaged.

The guy from the YouTube video might be right after all about the Company23 tool (the one with 3 lobes) damaging the Intake gears inside. Because the Intake Sprockets are not supposed to be removed from outside, but from inside.. not sure if I'm making any sense..

 

The FSM calls the tool used for removing the Intake Sprocket: "Cam Sprocket Wrench" and the Exhaust Sprocket tool is called: "Camshaft Sprocket Wrench", part# 499207400. It seems they specifically wrote it this way on the FSM for a reason.

 

If I’m analyzing this correctly, the intake sprockets are supposed to be taken apart holding the AVC Gear inside. While the Exhaust Sprockets are to be removed with the “Cam Sprocket Wrench”..

 

I know hundreds of Subaru owners have disassembled/rebuilt their motors already, but I’m not sure if anyone has looked at this detail since everyone seems to use the Company23 tool to remove the Intake Sprockets..

 

I’m curious to see what you guys think about this.

Edited January 4, 2022 by RumblyXT

[blackobxt]

I had out front motorsports do my avcs gears. I’ve seen what happens when you open them up yourself and put them back together without them being lined up properly and they bind. I’ve had out front do a few sets and never had any issues

[RumblyXT]

I had out front motorsports do my avcs gears. I’ve seen what happens when you open them up yourself and put them back together without them being lined up properly and they bind. I’ve had out front do a few sets and never had any issues

 

And that might be the best thing to do as they performed the service with the proper tools..

 

But what I'm trying to say is that we might have been removing those gears the wrong way all along. Company23 might have designed the wrong tool because the Intake Cam Sprockets has those 3 protrusions outside.

 

This should really be the proper tool to remove/install the Intake Sprocket/Camshaft bolt:

 

 

People just don't know their Intake Gears are damaged inside because they never took them apart after using the Company23 tool.

 

Wrong Tool for the job:

 

With my car having 210K miles, I'm pretty sure there might be some metal shavings inside the Gears. Why not learn to take them apart and service them ourselves?

I heard Subaru says they are not a serviceable item. But how could that be given metal shavings might end up inside and even prevent the AVCS system from working properly?

 

Notice the manual mentions the 1st tool posted above, not sure why Company23 tool came up with that tool with the 3 lobes.

Edited January 4, 2022 by RumblyXT

[RumblyXT]

I agree with this person.. the Company23 tool damages the Gear inside

 

[Soobyhobby]

Hello everyone,

 

 

 

I have an idea on the order of thing on what I need to do, but given I'm now dealing with a turbo motor and dual AVCS system, I might need your help on servicing these gears. I'm on a limited budget and these gears are not cheap.

 

.

 

A 2005 EJ255 does not have dual AVCS. Only STI came with dual AVCS in USDM. If your car has dual AVCS, you may have a JDM EJ20X/Y engine, which was a very common engine used to replace EJ255

[blackobxt]

From everything I’ve read, the reason people don’t is getting them aligned properly when putting them back together. They bind and stay advanced or vice versa. Outfront has supposedly developed tooling to align everything during reassembly and this tooling doesn’t exist outside of that (to my current knowledge). I’ve personally watched someone reassemble the gear using a camshaft to align it and had big issues with it.

 

Personally I think it’d be awesome if this tooling was available but I lack the knowledge to produce it and at the low cost of $100 to have it done, it seems hard to justify putting the time into it.

[blackobxt]

Sorry, I may have misunderstood. If you’re referring to removing the gear you are absolutely correct

[RumblyXT]

From everything I’ve read, the reason people don’t is getting them aligned properly when putting them back together. They bind and stay advanced or vice versa. Outfront has supposedly developed tooling to align everything during reassembly and this tooling doesn’t exist outside of that (to my current knowledge). I’ve personally watched someone reassemble the gear using a camshaft to align it and had big issues with it.

 

Personally I think it’d be awesome if this tooling was available but I lack the knowledge to produce it and at the low cost of $100 to have it done, it seems hard to justify putting the time into it.

 

That seems to be the problem indeed. The Gear inside stays advanced/retarded after being removed and people then get that dreaded P0011 code afterwards.

 

I saw the video and explanation by Outfront Motorsport. The tool they have to support/hold the Gear outside can be made, but as you said, it might just be better sending it to prep them for installation.

 

Makes me wonder now if the reason why they are miss-aligned afterwards inside is because people have been removing them with the Company23 tool..

 

BlackOBXT, Thanks for confirming it, I will buy the Subaru OEM tool instead to remove the Intake Gears. I can’t believe after all these years of enthusiasts rebuilding these motors, no one has looked/realized this. I’m not bragging about it, just saying..

 

Although I have seen how super tight those camshaft bolts can get and the amount of torque required to break them free. Hopefully the Subaru OEM tool will work ok without issues..

 

Before sending the Intake Sprockets to Outfront, I will disassemble them to see what they look like inside.

 

Outfront Motorsport video:

Edited January 4, 2022 by RumblyXT

[RumblyXT]

I know sometimes I tend to over analyze things, but I can’t help it. I am mechanically inclined and having worked 4 years in the Aviation Industry with Landing Gear Actuators gave me a broader perspective on how things are supposed to be done, at least from the mechanical point of view either way..

 

I just see people doing way too many hack jobs out there, and then they wonder why things went wrong. Subaru Engineers designed these tools this way for a reason.

 

Not that they would care, but I feel like calling Company23 and letting them know about this.

[silverton]

The FSM calls the tool used for removing the Intake Sprocket: "Cam Sprocket Wrench" and the Exhaust Sprocket tool is called: "Camshaft Sprocket Wrench", part# 499207400. It seems they specifically wrote it this way on the FSM for a reason.

 

I wouldn't read in to that too much. cam and camshaft are analogous in the automotive world. Also, the same company that wrote what you quoted, also wrote the wiring pinouts for my 2001 impreza... and they fried my head light switch because I didn't think to double check the FSM corrections first.

[RumblyXT]

I wouldn't read in to that too much. cam and camshaft are analogous in the automotive world. Also, the same company that wrote what you quoted, also wrote the wiring pinouts for my 2001 impreza... and they fried my head light switch because I didn't think to double check the FSM corrections first.

 

I think you are correct on the use of interchanging those words.

 

But the problem remains.. Company23 should scrap/discontinue both these tools..

 

 

I think this one is used for the STi on the ej257 for the exhaust Sprocket, not on our cars, but still the wrong tool to use..

[ATTACH]294703[/ATTACH]

Edited January 4, 2022 by RumblyXT

[RumblyXT]

Got a message back from Company23..

 

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"Thanks for the message. We have tested this tool on engines for this very reason and have found that the AVCS internals are capable of the assembly and disassembly torques required to remove and install the sprockets. We disassembled the sprockets after applying torques at increasing values. We have also found that the internally held design that you reference will fail at a similar torque to the internals being damaged with our design but it may be less obvious I suppose. In the case of the internally held design, you are unfortunately not able to easily remove the damaged sprocket either. But these torque values drastically exceed the factory spec. Let me know if you have any other questions.

 

---

Thanks,

Chad DeBaker

Product Manager / Lead Engineer

Company23

www.company23.com"

 

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 

I was thinking about the lead engineer reply.. Will the internal design of the gear hold the torque required to brake lose the cam bolt with the OEM tool without damaging the internals? Some of those bolts get so stuck, it's almost like they're welded in there..

 

In that sense, the Company23 tools seem a better option for removal/install.. I guess I'll figure it out when I'm there.

Edited January 4, 2022 by RumblyXT

[blackobxt]

Well, to clarify on my outback it was the worst I’ve ever experienced getting them off. I used the timing belt to hold the timing gear while my friend stood on a cheater pipe and it just started shredding the belt. I then locked the cam in place AND used the timing belt while my friend and I pulled on a cheater pipe before it finally snapped free. My initial thought was that the cam actually broke but luckily it was the bolt. Outfront was aware of this when I sent them in and they reported back that everything looked good they just cleaned the debris out of them. I have used the Subaru tool you’re referring to and it would probably have broken on my outback

[RumblyXT]

Yeah man, I have seen videos of people having to use a 6' long pipe as lever. Some had to drill the bolt out, others had to weld a nut outside to break it free..

And you are in AZ, I would have thought a northern weather would play a role in why those bolts get so tight in there, but it seems it can happen to anybody anywhere..

 

It looks like the problem is the hex hole is not deep enough on the bolt to generate the torque needed to remove it, hence it ends up rounded off..

 

If I'm not mistaken those bolts get torqued at around 70ish ft/lbs, but that is definitely NOT the torque to break them lose. It seems they get overtighten with the use of the motor over time.

 

I heard using valve grinding compound around the 10mm hex key can do the trick, otherwise, I'll use an extractor socket to grab the outside of the bolt's head, we'll see.

Edited January 4, 2022 by RumblyXT

[blackobxt]

It was when I lived in wyoming and the car was originally from wyoming. I’ve had some come right off with an impact and I’ve had some where I have to weld a nut and they usually come out after that from the heat from welding.

 

My exhaust bolts we’re just as tough but I was able to use my snap on rounded but extractor on those which really impressed me. I switched to the tun in concepts fu cam bolts so I doubt it’d ever be a problem again

[blackobxt]

turns out i still have one of those bolts that i used the snap on extractor on. its incredible the extractor didnt split

 

https://imgur.com/a/W0xq1Ve

 

forgive me, it seems ive forgotton how to add pictures directly onto the forum

[RumblyXT]

No prob. I couldn't see the pic but I know what you're referring to.

 

I follow Andy from Germany, he's got a phenomenal Subaru shop and a YouTube channel where he builds Subi motors for customers, state of the art stuff. He's got nothing but Snap-On tools and high end digital CNC machines. Check out the tool he uses to hold the Intake/Exhaust Cam Sprockets together..

 

I forgot I can't upload pics at work, freaking firewall.. you can see the tool at min 8:54 of the video

 

[blackobxt]

How are you uploading pics? I used to use imjur but non of the links it gives me actually posts the picture

[RumblyXT]

Click on 'Go Advance' at the bottom, then click the 'paper click' next to the white happy face, find the pic from your folder in your PC by clicking on 'Choose File' and upload it to the text.

But I'm at work now, the security firewall prevents me from posting here.

[silverton]

I've taken off dozens of these sprockets with the company23 tools, and I only ever had one failure, and it likely wasn't the fault of the c23 tool.

[RumblyXT]

Yes Silverton, that became the norm for years. But did you open the Gears later to inspect how the internals looked? Were there any scorings, big scratches, nicks or burs on the inner rotor and the inside of the housing from dragging the small pin?

That is in my opinion what would bring up the dreaded code P0011 later.. because of the bad operation of the internals due to using the wrong tool.

This idea that the dealer doesn’t want us opening the Gears because we don’t have the internal O-ring is BS imo..

I’ve opened Power Steering pumps and Oil Pumps and they are similar in how their internals need to be treated to guarantee proper operation later.

As I said before, I’m not bashing on Company23, they make fantastic tools, but the ones I referred to before imo may damage those Sprockets inside..

It would be interesting to see what tools Subaru trained mechanics use for this job.

Edited January 5, 2022 by RumblyXT

[RumblyXT]

Furthermore, we SHOULD open those Gears for inspection every time the motor is disassembled. This is in part where all the metal shavings end up after circulating the whole motor.

Otherwise, why then do those banjo bolts come with those filters..