Cleaning VVT camshaft sprocket assembly after spun bearing
 

Engine rebuild after spun bearing. New block and rebuilt heads.
Is it reasonably possible to clean out this assembly core piece with solvent and compressed air?

I don’t believe Subaru considers this item “serviceable” as there are no procedures for doing so in the service manual that I could find. Some passages have balls that appear to be pressed in and the plunger cannot be removed. Is there actually a way to disassemble this for rebuild that I’m failing to see?

If you look inside at the plunger, there is a circular retaining clip to hold the plunger and spring in place. It's a bit tricky to remove but can be done. Worth the effort because that's where the carbon chunks hang up (if there are any)

Oh man I didn't really clean this out when I did my rebuild...

Didn't I tell you too? Probably fine, I hope. I made a little tool to manually exercise the valve in place of the solenoid while the engine is running. Can bust up the crumbs if they're jamming the plunger. I've felt it firsthand.

You are indeed correct! What the devil do you use to remove it?! It’s far too small for any of my sets of snap ring pliers and auto tech picks. Stainless tweezer tips just bend.

Going out on a limb here but would ultrasonic cleaning work in this case? I see some guys here send parts to an industrial sonic cleaner without needing to dismantle the object itself.

OMG, right? The face on one end is parallel to the radius of the cylinder, like a piston ring. The other is cut at an angle so a jeweler's screwdriver can be used to get underneath and dig it out. It's a PITA but can be done.

edit: now that I think about it, it's not just an angle. There's an actual tab cut to facilitate removal. Just need to get underneath it. I found it by examining with my magnifier light.

I might try just hitting the related galleries with air while working the plunger. In my one experience, the plunger was jammed with a little crunchy fleck of something which worked itself loose before I realized exactly what was happening. As I was playing with the plunger, I felt a crunch and it went from only a couple millimeters of travel to sinking all the way in. My friend's ECU was toast but after he replaced it, the issue never returned.

I've tinkered with the phasors another owner sent me. That's when I figured out how to disassemble it. His was all clean inside but once examined, it's easy to understand how it would be jammed by a small grain of contaminant.

Just so you know, I took all 4 of mine apart and spent quite a while cleaning them. I ended up replacing one intake cam and now need to replace another exhaust cam because as soon as VVT activates, the cam won't hold timing and slams around.


I would have paid to replace all of them if I had known I would have to take my completed build apart twice because of my refusal to do so the first time

WTF? How many miles in?

I still haven't driven the car yet. It starts and runs fine until VVT kicks in, and then the cam sprocket starts freaking out and I shut the car off. I am assuming that for some reason, it's being goofy because the oil supply to it is being affected in some way. When I get to take it off soon, I'll take it apart again to see what looks strange.



Very well could be that something about how I put it back together or installed it was wrong, but the exhaust sprockets are simple so I don't see what I could've done wrong that lets it run normally until VVT kicks in.


It took about 45 minutes of run time before it started to do it initially, and now it's every time VVT kicks on. I have datalogs somewhere that show the cam timing on the gear going nuts as soon as I start hearing the sound, so something is wrong with it that was not wrong before I spun a bearing and cleaned it

The intake sprockets have the lock pins, right? Do you know if your oil pressure takes a hit when VVT engages? Gross leak on the intake phasor, maybe? I agree that there really isn't much to them.

Also make sure you haven't cross connected the VVT solenoid plugs (intake to exhaust). It's easy to do (everything seems "ok" and fits) and makes car run fine until VVT engages and all goes crazy. I have rebuilt FA20 with spun bearings and never had a damaged sprocket. Remember there's a super fine metal filter in the oil supply to each head.

Eduardo

This is probably what I need to do. I just hit a P0017 when I get on it with WOT at high RPMs. The idle gets all wonky if I get into the VVT ranges.

I've read a few of the threads on this but they all just talk about the sprocket being messed up.

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