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Knock Knock!!

26K views 73 replies 7 participants last post by  wrxwrb14 
#1 ·
I think my WRX hates me.... Drove to Atlantic Beach and back yesterday and everything was fine. Wake up this morning to go to work....rod knock...f my life....what do you all suggest for rebuild kit for a daily driver. looking for 17-18psi boost and eventually a bigger turbo and what not. I have looked at six star speed and they have some decent stuff. just wondering whats out there.:crying:
 
#3 · (Edited)
Yes, it sounds so innocent doesn't it? That dreaded knock knock knock, or tap tap tap of a rod bearing.

My car Club mates say that with ongoing motorsports involvement it'll happen - sooner or later.

I feel your pain mate, as I've just been through it.

In hindsight I would likely install a JDM low-mileage equivalent instead, to reduce the time without wheels, but either way expect it to be considerable.

Best is to keep reminding yourself that the end result will be worth it, as the motor will be better then new and worthwhile to work towards.

Options I am aware of are:

1. OEM rebuild,
2. Performance rebuild, i.e. built motor,
3. JDM low mileage motor replacement, and
4. OEM replacement.

Expect to be down for a month. I chose option 2. and it took 2 months.

 
#4 ·
Oh were doing a performance rebuild. i do not wanna have to pull the motor and heads a third time. Its only been back on the road 1200 miles since i replaced 2 pistons and a set of rings.....i cant believe i went to sleep and everything is fine and i wake up to spun bearing.

So i guess what i want is to build the motor strong enough to handle a decent amount of boost and so i can have some peace of mind knowing i wont have to pull the motor every other month to make repairs. Can anyone make an suggestions as to build kits or is it worth it to get things seperately. ill be doing the work myself, with the help of my father ( parts and service manager of the subaru dealer i work for)
 
#5 ·
Spun bearings are usually from oiling issues and rebuilding an engine is a very specialized task. It's done best by a rebuild shop that's familiar with performance Subaru engines, especially if you are going to dial the power up. Shops will address fundamental weaknesses and consider the target power levels.

Dealerships and most service shops simply remove and replace engines and ship them to other more specialized shops for rebuilding and assembly.

Pistons in the EJ257 motors are vulnerable to knock events and there are oiling limitations of all the flat 4s in sustained high-G cornering. That's where mine let go.

The Truth Behind The Subaru EJ-Series Engines - Tech-Knowledge - Import Tuner Magazine
 
#6 ·
I cracked a stock piston in my stock engine.

Then I cracked two cylinder walls in my rebuilt and bored out stock engine - pistons were fine :)

Now I'm rebuilding it again with brand new case halves and a whole bunch of goodies. It's been in the shop for a little over a month now, but I expect it to be back in the next couple of weeks.

As much as it sucks, it's just the name of the game man... gotta pay to play.

Good, fast, cheap: pick two.
 
#7 ·
^^^^ Surely have to pay to play. I don't want anything to crazy. I nice 325-350hp daily driver that is reliable and fun to drive. Am i asking too much? lol. Im going to do a bit of research and see what i can find. Ive read where some people have sleeved the block and all but im not too familiar with that.
 
#8 ·
Sleeves are good if you're looking to make stupidly high horsepower numbers for a short period of time. They're ridiculously strong in the short term, but in the longer term, the differences in metal will cause head gasket leakage issues. You're better off going with a closed block.

I'm actually going to be selling most of my old 365 hp setup in the very near future if you're interested: http://www.wrxtuners.com/forums/f194/parts-feeler-some-really-good-stuff-52153/

My build should be complete soon, so I'll try to post prices and pictures shortly after that.
 
#11 ·
Well I'll take a wild guess and say you spun a bearing.
If so,Congratulations u have joined the EJ spun bearing club
Mine started as a knock and ended shortly after as the sound of a can of marbles in the engine with metal shards of a leftover bearing that got shredded and sent through pretty much everything.
Needless to say not much was salvaged from the old engine. Hopefully you make out better than myself.

Good luck man.
 
#12 ·
Okay I'm gonna go out on a limb here and ask? This makes the second time you've had a motor tank, maybe you should be looking into the tune. I ran the dog snot out of my old 2L and the only reason it blew was because of my own stupidity. In any case I recommend a new motor from Subaru and go from there.
 
#13 ·
its a plain old cobb stage 2 tune...and since i did the ring lands its only been 1200 miles. Im pretty sure when the ring land cracked and it ran low on oil it caused the bearing issue, but when i pulled the motor and heads and put the new pistons in there was NOTHING as far as metal shavings or anything for that matter in the pan or in the heads. i never split the block and or disconnected the connecting rods cause there was no visible damage to anything. I pushed the wrist pins out through the access hole in the block. replaced the piston that was cracked and a new set of rings. How would the tune cause a spun bearing? thats usually due to lack of oil which i had happen when the ring land cracked.
psinuse your 2l and my 2.5 or not the same engine. i new motor from subaru is your suggestion? i think ill tear the motor down and see what the problem is before i waste 6grand.
 
#15 · (Edited)
Tearing the engine down is a good idea. At least you'll know why it failed.

Perhaps particulates got into the bearings or oil passages from the 1st failure, and it didn't affect them right away. I heard that they can collect in an oil cooler.

And a new motor from Subaru is certainly the fastest way to get mobile again. It's not a built motor, but there's a cost to 2 months of waiting for one too.
 
#22 ·
Okay I have a couple questions and then I can try and help you figure out what's going on.
1) Now the first motor had bearing failure correct?
2) Did you buy a new motor or just replace the bearing?
3) Did you replace the oil cooler after said bearing failure?
4) When it had the ring land failure did you just replace the piston and rings?

The reason I said the tune, is because knock can cause bearings to fail and if you have lots of knock then you can see where that is going. The reason for this is the added vibrational (big word score in scrabble by the way) stress caused by knock, which is called pre-ignition, is send down through the rod and into the crank, which the force of the knock is actually trying to push the piston back down the hole before it reaches it's full rotation. That added stress will easily destroy a bearing quickly. Now I'm not trashing Cobb or anything, but every car is different.
I'd highly recommend finding a 702 casting. Those are what I try and use, but that's personal preference.
 
#23 ·
PSINUSE!! :) Dood that makes so much sense!!!! Had the knock sensor going off like crazy for a long time before it ever started with the rod knock. Pulled the motor and didnt see any signs on metal shaving or damage in the oil pan or in the heads on the cam journals(all before it started with the rod knock). I never split the case or pulled the connecting rods to see if it had any damage to the bearing. Put 2 new pistons in and a new set of rings. Drove it for 1200 miles and everything ran great and sounded good. then one morning i go to leave for work and start it and it sounds like marbles were rolling around in the bottom end. Im willing to bet the initial ring land crack and knock caused damage to the bearing and it took it a while before it started to make noise. I have two blocks here, where do i look to find the casting number? i looked on one and didnt see 702, 703 or 704

to answer your questions, this is still the first motor, we did the pistons and rings first cause i was getting a missfire code and my knock sensor was going off like crazy. we have never put any bearing in it, only the two pistons and ring set because i didnt realize that the knock from the cracked ring land could cause bearing damage as well. And yes i caused the ring lands to crack. cobb sf intake with the TP ots tune cause it to over boost. Im fairly certain thats what burned the ring land due to it running lean which then lead to all these other problems
 
#25 ·
p.s. The car doesn't hate you.
p.s.s. Also you should replace the oil cooler. That thing traps all the fine particles in it and then when you go to drop a new motor in those particles find there way into your new motor and guess what happens then? Yes they are pricey. I think Subaru charges $235 for them....damn dealerships.
 
#27 ·
Yea oil cooler is surely going to be replaced, hopefully there is no damage to the heads. Im lucky enough to work for the dealer so ill get the part at 10% over cost. still pricey but worth it. Turn out the spare block i have is a B25C 704... womp womp. cant see the number on the one thats in the car yet. ill find out on saturday
 
#28 ·
So heres the parts list so far :

Manly B series drop in pistons
Sti/WRX OEM crankshaft- they are the same PN in the subaru parts catalog.
Manly H-tuff Rods
King rod and crank bearings
STI oil pump

i have a spare OEM 704 casting block im going to use. I will probably port n polish the wastegate on the turbo so if anyone knows of a tutorial that would be greeeat lol.

there is no oil cooler on the car right now, should i look into getting one?
 
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