Knock knock, who's there? BIG ENDS!

[B4 2000]

 Wiretap']

[quote name='evowrx said:

hard to know whats accurate on the net these days. especially between different countries...

/quote]

Exactly, which is why unless I get the information from Subaru or my own measurements/checks there ain't no way I'm going to share it.

Yes I agree it's hard to find accurate info on the net, I had a service manual and it did state the same but can't find it, think its in the storage with the rest of my stuff that I left in Dunedin.

[dubbedup]

 Skinon! said:

s*** yea, 7K, i want a forged rebuild and a blowjob while i wait for it to be done in 15 minutes haha.

But super serial tho, cheers for the input but is there any clubsubbers in qtown that have swapped theeeese over? Give me a GTR or Rx7 i can change the stock twin turbos and a gtr in place but havent worked on many suby's before, and the engines on these look like a arsehole to change.

Do these ones have the pin ontop of the gearbox you gotta remove?

Maybe im just getting lazy...

probly the same difficulty.. just give it a crack,

[Wiretap]

There's a specialist in TT engines in qtown actually... Get hold of ReubenH

[WRXONP]

hold the boat

big end bearings cannot be "on their way out"

theyre either good - or theyre knocking their little ass out

and if theyre knocking you will normally loose oil pressure - as the massive clearence in the big end allows the oil to flow out resulting in low - or no oil pressure

normally a big end will spin (hence why its called running the bearing) - it can weld it self to the crank - and completely flog the rod out -

once it starts knocking - its terminal - and you know it - its not quiet at all

what im getting at are you sure its a big end and not just a bit of piston slap

[Guest]

 WRXONP said:

hold the boat

big end bearings cannot be "on their way out"

theyre either good - or theyre knocking their little ass out

and if theyre knocking you will normally loose oil pressure - as the massive clearence in the big end allows the oil to flow out resulting in low - or no oil pressure

normally a big end will spin (hence why its called running the bearing) - it can weld it self to the crank - and completely flog the rod out -

once it starts knocking - its terminal - and you know it - its not quiet at all

what im getting at are you sure its a big end and not just a bit of piston slap

piston slap wouldnt just rear its head though but still a pull down if its the engine anyway though.

if a beb is gone it is fucked though not subtle and just gets louder. had a big end go in gsr got louder everytime i started it. didnt matter was cheaper to replace than rebuild.

do bearings spin and weld in a fluid motion or weld if you keep driving?

[WRXONP]

well the only way it can knock is excessive clearence - its basically the rod knocking on the crank (hence the other name of rod knock)

keep running it will weld to the crank - which is purely from metal on metal and getting very hot

ive seen alot o big ends go on various cars- vans - trucks - they will knock quietely at first and wont take long at all to be knocking like a sledge hammer on the crank -

[Guest]

i just thought the spun bearing would pinch and cause the welding through friction/heat. if it was knocking side to side i wouldnt have thought it could weld. no real world experience though.

[Wiretap]

It won't knock side to side forever given the way a crank works, the force will never be directly parallel with the bore

[WRXONP]

rod knock is definatly not as loud as a rod bolt letting go ! now thats loud when the rod pops out to say hello and the engine keeps running

but seriously to the OP - how sure are you that a big end is knocking ?

[Skinon!]

Well i am pretty sure its getting louder... Maybe im paranoid, i made a video of it ill try upload it but im on my stinky iphone

[Stoffa]

I had what I thought may be my big ends knocking when I first got my car and I was uneducated, turned out to be a waterpump on its way out and knocking.

Has an experienced subaru mechanic looked at it? if not thats what you should do first. not your local garage either, a subaru dealer or specialised subaru workshop.

$200 to fault find is cheaper than replacing your engine

[Drunkenmonkey]

ReubenH is in qtown could offer a bit or free advice, hes expended a beb in his gtb

[WRXONP]

Also when harmonic balances are failing trhey will also knock and vibrate -

Also crank float (worn thrusts) will induce knocking

[ADIKT]

Fuck it could be anything!!!!! take it to a specialist!!!!

[Skinon!]

Did water pump etc not too long ago...

Heres the video, you can hear it better near the end of the video....

[Wiretap]

Hard to tell, could be bigends or could be a blown out uppipe from the sound in the video.

[WRXONP]

i can hear - a whiney ass turbo or power steer pump thats or sure - the "knocking" whilst revs are rising sounds to me like piston slap - allot of subarus make that sound whilst revs are rising

the noise on idle doesnt sound quite right tho - but in saying that - a big end will ALLWAYS get allot louder when revs rise - i can only hear what sounds like normal piston slap when the revs rise

btw big ends will make one hell of a vibration - you will feel the knocking action if you have your hand on the motor

the noise on idle sounds like it could be a exhaust leak as it doesnt do it on when revs are falling - a big end will knock 24/7 all day long - an exhaust leak will not make noise on decell

edit * after watching and listening multiple times - when u hold the revs at its highest there for a while - the noise is nearly gone - that would indicate to me its definatly not a big end noise - as the noise gets louder with more revs when a big end is gone - seems to me that its some classic piston slap as it goes away in the higher revs

[funkytown]

How cold is the motor in that youtube?

[Stoffa]

to rule out big ends just drain your oil, if you've got gold glitter its bung

[ReubenH]

I've pulled all the numbers from the manuals independantly (Well, with help from a mate in japan with all the Jap manuals) of any of the info in this thread so far... and guess what... all matches up perfectly

BH5A, EJ206 9.0, EJ208 8.5

BH5B, EJ206 9.0, EJ208 8.5

BH5C, EJ206 9.0, EJ208 9.0

BH5D, EJ206 9.0, EJ208 9.0

And skinon, yeah I live in QT, have hookups, and am handy with a spanner. If you got the space to work on the car, I can lend a hand, no sweat! I've done many many a TT job now...

If you want me to take a look at the car, just send me a txt as per the PM.

 WRXONP said:

edit * after watching and listening multiple times - when u hold the revs at its highest there for a while - the noise is nearly gone - that would indicate to me its definatly not a big end noise - as the noise gets louder with more revs when a big end is gone - seems to me that its some classic piston slap as it goes away in the higher revs

Lol... When my big end went, at first there was only the slightest of ticks just as you weregoing from on the gas, to closed throttle. It was loudest at the lowest revs, higher revs it was drowned out.

from that point on, i only drove 20KM before the engine was so F**ed it couldn't run without a fair bit of gas on the pedal. You should have heard it driving up my drive, it stalled 3 times before I had to rag the s*** out of it just to get it up. I just discarded the entire short block and everything bolted onto it after that. Bought new oil pump and cooler for the new block.

[Guest]

I'm also in qt have done a few motor swaps now flick me a pm if you need a hand always keen lol

[Skinon!]

Hey, the motor is cold in that vid but not dead cold its about 18deg in the park, but i know what piston slap is when it's cold but it's a noise that wasnt there before...

Hopefully its not the big ends, the noise goes when you rev it, but i thought it would anyway cause of the oil pressure goin up?

I pm'd Reuban, yea would be mint to talk to you qtowners, i been here 15 odd years so prob know a few, who know a few haha

[Drunkenmonkey]

That's a hell of a knock sounds like big end to me,

Got a long screw driver? One trick is hold it on places and move around see where it's loudest with your ear on the other end

[funkytown]

i only asked how cold as thats what my forged engine sounds like on warm up. possibly bit different for a factory motor though.

what does it sound like after say a 20min drive? same less or more 'knock?

drunkens trick is a goody, also might be be worth a compression test

[Guest]

Would piston slap just begin out of the blue? i thought the concept of piston slap was the larger bore clearance with forged pistons when cold.