Bank 2 Valvetrain Noise
After replacing the sound deadening for the B2 side injectors, the sound persists.
https://youtu.be/_ev3tQDooz0 This is what I believe to be the “sewing machine” sound when warm, which is addressed by Subaru’s TSB 02-151-14R. It involves the replacement of multiple valvetrain components “to reduce a tapping sound (sometimes described as “a sewing machine type” sound) which may be heard coming from the left-hand (B2) side of the engine when the engine is warm.”; copy/paste directly from the TSB. I have worked on a handful of 2014+ 86s, and haven’t heard this sound in them. I’ve heard it in 13s, but to a greater degree usually. Looking for the noise with a stethoscope didn’t turn up anything exciting, as most of the sound is drowned out by the HPFP. Should add that I recorded this after a 185* warm start, with IATs of about 100*. The sound also disappears after blipping the throttle to about 5 grand, which I have a hunch is due to cooler oil being dumped into the B2 head. |
That sounds nasty. I hear a bunch of not-ok valvetrain shit on top of the normal stuff.
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A lot of the noise you hear is the trans too though. It has a prolite flywheel. Lol |
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Subaru is a pay to play car. |
Further documentation:
https://youtu.be/kRAhoA6oadE The sound only occurs after a hot start, and usually only after it’s sat long enough to suffer heat soak. This video is after 40 minutes of very hard driving. Lots of pulls to redline, CT spikes of about 213*, IAT spikes upwards of 140*. This leads me to believe that it’s strictly an NVH issue. Especially because the revision includes new valve clearances for the B2 head. If it dies, it dies. I’ll replace the engine in 6 beers time. Lol |
You can try Seafoam. It can ease up the valve train. One 16 oz. bottle. 4 oz. goes to oil, 12 oz. goes to full fuel tank. Replace oil after half tank fuel used. Carbon and sludge build up can increase the valvetrain noise.
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Sounds perfect in that clip! :iono:
Maybe valve lash is just a touch on the loose side and snugs up as the valve stem expands. I understand that, on this engine, it's preferred to err on the loose side because lash decreases on break-in. |
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In this case, it’s literally a design fault on Subaru’s part. The 14+ engines have revised valvetrain geometry to reduce the SOUND. According to any information I can dig up, on top of observations I’ve made when working on these cars, it’s strictly an NVH issue. 2013 FA20s just kinda sound like single jingle KAs, and that’s okay I guess. Lol |
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I think the issue is mostly due to the angle at which the rocker acts upon the valve. That, and because the valvetrain component’s CoTE is less than the head, I believe valve lash actually increases with heat. Which would explain why it only happens after heat soak. |
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