Subaru Knocking Noise Solved

This was a quick teardown & diagnosis of what I found while messing with a 2.5L Subaru engine. Car had 60k miles w/ all maintenance records & oil changes, ...but somehow developed a knocking noise. This is what I found out after a bunch of research

[grumpycat_]

That engine damage is from oil starvation in cylinder 3.
EJs are notorious for spinning bearings (Cyl. 3 in particular ) when low on oil.
Horizontally opposed engines are what they are and they need ALL the oil ALL the time.
Hard cornering when you are even a under 1 quart low will cause this exact issue, the resulting knock and this exact engine damage.

Moral of the story ... When driving a Subaru check your oil every time you fill up you gas tank and make sure it at the top of the fill mark.

[nicholassuriano]

I bought a 2017 Subaru Impreza brand new from the lot.... put on just under 55k miles on it and this exact same noise happened. I always used genuine Subaru oil filters. After 7 recalls, rear brakes and rotors replaced under warranty, engine coolant always disappearing along with other issues I traded it in for another new vehicle. This was my first and LAST Subaru. Wish that they were still made in Japan!

[Tomas.X]

NOTE: There are many things that can cause "knock" or "tick" or similar sounds. Some (e.g. a misfire, will produce a definitive DTC.) In my case, my college student son has a 2006 Impreza 2.5i. He is ALWAYS running around, thus I have little access to it. After fixing a code indicating bad O2 sensors (with new OEM Denso upstream and downstream sensors) all was well for a while...then the dreaded P0420. I tried the "hacks" to clean the cat, none worked.

I finally got some time with the car and ran a new scan. I found the upstream O2 sensor was reading 0 volts (the downstream was OK.) This would explain the code. Now I have to get under the car, remove the belly pan and determine if it's a gasket (PLEASE!) or a cracked manifold.

(BONUS SUCKAGE: It's a used Texas car - I'm in Wisconsin. Low mileage, no rust, decent CarFax service records, but no idea if it had a timing belt. So I bought a complete OEM kit + AC & PS belts, water pump, the works. I'd take it on buy have a shoulder injury and an import shop was going to do it for $300. And then my son comes out from a store 2 weeks ago and there's a "spray" of coolant throughout the engine bay, mininal on the ground. Resevoir was not down much, cap too hot to remove. He drove the 6 miles home, no smells, no more leak, no exhaust steam, no smoke. Nonetheless, my import specialist tech said "small head gasket leak" and told me not to do the belt job if the engine gets pulled for new gaskets. AND don't bother with the exhaust leak work/expense. Thing is, messy as the blast as coolant was, it was minimal, and denoted a gasket failure outside the coolant jacket inside the head/block. I poured Bars Leak Head Gasket repair, followed all instructions, light then moderate driving.

So if the HG is repaired (major, no way...minor/tiny...decent chance) I invest in the exhaust fix and get the belts done. If the HG absolute needs replacing, I throw at least some of the money away getting those things done. I'm a Subaru nut and it's my first HG issue. And of course, it happens along with other issues, complicating it all.)

[KrmtFrg]

I dont know if your analysis about the filter operating in constant bypass is accurate. most folks dont use OEM filters and if it were true that non OEMs killed motors, more EJs would be dying. Subarus filter really isnt anything special - its a rebranded Fram.

[sihop]

Some advice : dont tell anyone you know how to fix cars otherwise you will have all your friends and family parking their broken cars outside your house. I found that it was handy for keeping my own car in good running order, but was also a bit of a curse ..

[VotEtoPizdets]

Now im worried. My 08 impreza is starting to emulate this engines noise. Sounds like a sewing machine and the knock is so very faint. Also, on acceleration at low rpm it makes a rattling noise almosts like an exhaust clamp is loose but all the heat shields were removed for a test run and the entire exhaust from the header to the tip is solid with absolutely no loose parts, so i know its the engine internals that are the culprit. Ive never heard an engine make that rattling noise before. Any input from anyone would be of tremendous utility to me. Thanks for the content. Keep up the excellent work everyone!

[costcocombopizza]

Gone through two Subarus. Might just sell my Legacy soon. If it was cheap to fix, but on a budget...sometimes some dreams your got to let go and cherish the memories.

[mariopic]

this is why i use same filters the acura integra type r uses filter fits subaru and its got high flow rate and wont by pass as easy unless u got blokage

[jimgordon]

Subaru uses Fram filters with Subaru printed on the side.

[norakat]

Looks like carbon buildup - can result from poor quality gasoline. Not for the guy In this video but for those experiencing typical knocking/pinging/rattling noise, You can try doing some Seafoam engine treatments through vacuum hose for the brakes or intake, followed by using premium gasoline.

[DanTheManIOM]

LOL, I don't know if you can hear it.... oh YES we can....I did not know that about genuine subaru oil filters.... guess what I am buying today... THANKS

[HellSSDrifting]

My knock is like someone beating on the car

[raniafatehwasim]

I don't know may be just a general assumption, but everytime I saw a Subaru passing through, some of them got this sound..

[bachelorsuite]

Knock knock

Who's there?

Subaru

Subaru who?

Knock knock

😂

[DGXJ]

Subaru special high pressure oil

Biggest lie out there they charge 10$ for a $4.29 basic fram filter, cut it open and compare to the basic are the same

The only filter I use is wix xp 57712xp it’s the only aftermarket filter that meets the 23psi bypass criteria and it is much better filter with metal retaining caps, metal bind for the filter material, metal bypass valve, and and better quality silicon.

The Subaru filter is all cardboard, glue, and one piece of dogshit rubber pressed into a metal can, it’s trash, don’t use it

[dannymartinez]

So you recommend using only Subaru oem filters? Any other brand u recommend other than oem

[wilsonjohn]

Drain that piss 0W 20 oil out. Put in Valvoline 10W 30 full synthetic with a quart of Lucas synthetic oil stabilizer and she’ll purr like a contented kitten.

[justinboudreau]

How much did it cost to fix? Having the same noise coming from my 2015 wrx.

[DanTheManIOM]

John, first 13 seconds seems a different noise that later in video. My ej25 DOHC just started making this noise and seems to be coming from the driver side (long screwdriver to find loudest area), it ramps up like the sewing machine. Based on what you found, I am going to check oil filter, I think I did use a wix ?? / will look at that. Timing belt new, but there was some oil/great in the bottom of one of the timing covers. I was driving along and bam, high temp, lost power, and made noise, shut it off and towed it to my automotive class (paint and body), start it up tonight, and I now have a sewing machine. think I have to pull it and look around ? If engine builder did not pay attention to valve caps, could that have cuased this ? IDK, any advice is appreciated.

[kaibotski]

I have a similar noise but goes after after 1-2 seconds and only on cold starts. Would rod knock go away when warmed?