hello I'm new here and mostly new to Subaru world,this is my first Subaru ever but not first time working on one. Bought a 2011 Subaru wrx premium wagon about 6 months ago at 105k mile. It already been slightly modified by previous owner stage 2 with FMIC and full exhaust / intake setup and custom pro tune with Cobb acessport. along with some grimmspeed stuff EBC, light weight crank pulley, AOS. I have just reach 114k mile, few days ago at late night when i pulled into a empty lot to park up to eat my dinner it started making " cardboard box of rocks" like rattling sound so i slowly drove it back home and parked it. so i started looking into the noise issue next day and was reading that it could be timing belt tensioner going bad or rod knock. So i gotten a new timing belt kit since it still had the original timing belt on it. swapped it with new belt and tensioner. still made the noise so i figured OK it most likely something went wrong in the bottom end. next day i got started with draining the oil and dropping the oil pan to see if i can find any play in the rod bearing. the oil it self had small small amounts gold metal flakes and looking in the oil pan there was some some of gold flakes. Most of the gold flakes was on the windage tray. I checked each rods for slight bit of play, non of them have any movement or play on them not even slights bit. so i had a friend turn the crank slowly back and forth see if we could get it make slight noise or feel a slight play but nothing at , like as if there's absolutely nothing wrong with them. could this still be really early stage of rod knock or bad main bearings making that "cardboard box of rocks" sound, trying to pin point this issue asap so i can get back to working soon. I made some videos on my iphone
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I think i may have fixed the video not accessible issue i had the video on photobucket but it would just show blank white screen when i play it back. The gold flakes did kinda have that copperish color tone to it but its more closer to bright yellow gold much like your gold necklace chain. while still looking up what this issue is, i came across old post from nasioc where one of the poster had said stated that a spun bearing would be heard on idle and failing rod bearing are most prominent on deceleration, while failing main would be audible under load. Is this poster statement correct? this does somewhat follows with the "knock like"sound except the "most audible on deceleration" part cause the noise is most audible when you put slight load on the engine between 2500rpm-3000 rpm. On decele or when you left off it goes quiet/ silent until it hits that 2500-3000 rpm rev range. also while checking this issue i had my Cobb AP plugged in and i remembered the knock value count kept counting up each time ti would make the noise. On idle after being warmed up and after recording the first 2 videos at first it didn't make any of the noise on idle but after the last or 4th video i recorded i did started to hear noise very slightly on idle. sound volume was similar to your TV sound volume turned down to 5 or 7 really low volume but still can be heard clearly if the area was really quiet. I think the previous owner got rid of the stock oil cooler. when i changed the filter i noticed it had a those sandwich plated adapter on it with a some type of temp senor in one of the ports( assumed the previous owner had some type of oil temp gauge installed at some point and uninstalled before selling).
I forgot to mention that the noise also gets faster as the rev climb up towards 3500rpm and get abit louder then starts to slowly fade away as you higher past 4000 rpm but when you left off or on deceleration it doesn't make the noise until the rev hits the 2500-3000 rpm
honesty the previous never told me much about the car and its mods and stuff except he did have the car tuned with a custom tunes for all the mods on the car. when i was putting new timing belt on noticed the old stuff had gates brand name on it. the car is currently right now in pieces getting the motor ready to come out. I also gotten set of new head gaskets as well as new bearings to use on rebuild. So this is possibly a cracked ring land and main bearings starting to go? the previous owner also had said it made about 335ish whp on the dyno from last time he got it tuned.
update i got down to the short block noticed a few things with this motor. had it cylinder heads replaced/ or refurbished (most likely new heads ) secondly the crosshatch marks on the cylinder walls are still fresh looking looks like it has maybe 30k or less miles on them. also noticed this block has the newest STI nitrated forged crankshaft fitted into the block. looking back when i first got the car and plugged the cobb AP in i saw the previous owner had redline set to 8k rpm which i knew this was way to high as i figured this motor was mostly stock or so i thought since the previous owner has fail utterly to mention this type of work being done on the car. so i lowered it down to 7200 rpm and kept it there. to me this seem like someone who was working on this engine didn't know that they're doing at all and don't really understand that you can't just rev out the motor to 8k plus unless the motor was setup to beable to do high rpm. the car didn't have any oil pressure gauge installed otherwise i would most likely have caught the issue way earlier in time save me work. so now i'm having to do a rebuild on a recently rebuilt motor.....
forgot to mention the motor still had the 10 mm oil pump and have learned that the jdm ej20 that redline at 8k rpm have bigger 12mm oil pump which i think the previous owner didn't know or learned before attempting to do a "high rpm". feels like he wanted to rev high like them jdm ej20 and or like the Honda engines. I just don't get why people just do this it not hard to do little research and he coulda gotten some advice from some well know subi shops i'm sure they woulda told him which correct oil pump to use for that application.
I rebuilt the engine with new Manley Forged pistons and Rods. upon disassembly all my bearings even my main bearings was bad bearings from cylinder 1 was starting to go and was progressively worst as you got the cylinder 4. Also noticed my oil pickup tube had a finger nail crack line by the mounting flange end [most likely the main reason for premature bearing failure] but Luckly I had saved the engine in time so my crank journals was all still in perfect shape. Also took this down time as opportunity to fit on my gt35r turbo.
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