gearbox primary shaft or crank main bearing ?

[andy-m]

i fitted a recon gearbox about 6 months ago and have done about 6000 miles since then.

after fitting the box, i went for a drive and noticed a sound. it sounds like the edge of a gear was hitting the gearbox casing inside very slightly. the sound is in time with the engine revs and not the wheel speed so i figured it was the primary shaft.
i figured, it came with a 3 month warranty so i decided to leave the box in and it would either fail or it wouldnt.
well, 6 months later, the sound hadnt canged and the box hadnt failed.

tonight on the way home from work, i was sitting in traffic near a wall, which usualy enables me to hear the sound a little louder.
i noticed that i dont realy hear it on accelleration, quietly when i roll off the gas, but a little louder than usual when i hold my speed. I can even hear it rattle if i remain stationary and blip the throttle just as my foot comes off the gas, then it dissapears as the revs drop back to idle.
when i got home, i left the car running and got out and had a listen. i can now hear the same noise when its idling.

does this sound like the primary shaft or something on the crank, like big end or main bearing ?

if its the box, i can find another £300 for a recon, if its the egine, i think i'm gona be without a car for 6 months

Edit: added video:-

[2-jaffacake-tone]

so when stationary the noise is present, have you tryied putting your foot on the clutch when noisy (stationary)? if its still noisy when depressed then it rules out the box.

[andy-m]

oh poo it must be on the crank then cuz its still there when i press the clutch.

does the engine have to come out for big ends and main bearings ?

[2-jaffacake-tone]

yes it dose, could still be realease bearing of course.

[andy-m]

u mean the one that pushes on the diaphram?
I dont think its that cuz the sound would be different when the clutch is pressed to when it isnt.
also, teh way the sound isnt there on accelleration, is on deceleration, and is louder when i hold steady makes me think that the shaft causing the sound is moving forwards and backwards a little to make the sound.

do u know how heavy the engine is ? could 2 people lift the thing out ?
I am thinking of getting a recon botom end, although i would still have to wait till after x-mas till i had the cash

[2-jaffacake-tone]

would be worth getting it checked out 1st before changing the engine, you could lift the engine out with 2 people as long as 1 of them is magnus samuelsson need a hoist really.

[andy-m]

i'm fairly sure now its the engine.
its not the thrust bearing.

i know 2 people that could probably beat the crap out of geoff capes in his prime,so i think i'll get them 2 do the heavy lifting for me.
now all i gotta do is save up 2 get a new bottom end.

i'll try and make a meet sometime between now and x-mas n see what others make of the sound.
unless it gets majorly bad between now and then of course.
at the moment, it dont seem that much worse than it was 6 months ago.

[Nick]

when mine started to go it only did it on revving around the 3k mark, souded like a tappet sound to begin with but as time goes on it gets louder, Doesnt make the noise when engine is cold as oils thicker but when she gets warm it now sounds like someones throwing a few spanners into a tincan, If its any concellation i'm in the same boat, oh well mines under cover for the winter, saves me polishing the bloody thing i guess :P

If your unsure theres hundreds of videos on you tube of knock noises, just search for impreza knocking .
GL

[andy-m]

yeah that sounds like it. it seems to be more noticable at about 2500rpm and if i hold a steady speed, it sounds like spanners in there rather than a regular knock.

Ive had a quick search for engines and can only find ones listed as "short". would mine be a short or are they all short ? mines a 94 jap import WRX GC8C48D.

this is what i'm looking at as a replacement at the moment, but i wont have the cash till next year:-
http://www.grahamgoode.com/subaru/pa...60&item=GGS918

[asperformance]

no offence but unless you've only done a few miles in the last 6months its not a crank/bearing issue..........once they start they normally destroy themselves within a few hundred miles max

hard to say from what you've said but either r/bearing or more likely the spigot bearing in the flywheel
could even be the dust shield on the bottom of the engine catching???

[andy-m]

Ive done about 5-6000 miles since the new box went in.

the bearing in the flywheel, is that the needle bearing that sits in the flyweel where the gearbox primary shaft sticks in to it?
If thats the one your refereing to, would it still make a noise when the car is in gear and driving ? cuz the primary shaft and the flywheel are both rotating at the same speed then and i wouldnt have thought it would make a noise then.
I did have a few tries at getting the bellhousing to mate up with the engine before i finaly got it to go so theres a possibility that needle bearing could have become damaged.

As for the release bearing, would the sound be different when the clutch is pressed or released or would the sound remain the same ?

[asperformance]

yep the one in the flywheel................

can sometimes change or even go away.........

[andy-m]

thanks.
i think next weekend i'll have the box out n try changing the 2 bearings then and hope that cures it.

[andy-m]

had to replace the radiator today, so i managed to record the knocking sound on my phone:-




anyways, i put my head over each pair of pistons, and above the centre of the engine. the sound is lodest when i put my ear behind the alternator.

what does this sound like to you guys, crank ?

[Nick]

that sounds to me like the ol bottom end m8, thats how mine started

[andy-m]

i was thinking that as well when i realised it was loudest with my ear right behind the alternator.

Oh well, looks liek i;'m on the trains 2 work for a few months then.
I'll just use the car for short necesairy trips like food shopping n stuff untill I can afford a new engine. That is unless it gets realy bad b4 then