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Spun Big End Bearing?


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Alright those unfortunate to have heard this noise before come and confirm what I think I have diagnosed.

A few months back my rb26 started making a bit of a ticking noise at startup, that would trail off after about a second (read oil getting to said spun big end bearing).

It also started making the same noise between about 2500 and 3500. Power seemed fine, thought it was a loose belt or something.

I have been trying to get it ready for the track so have spent a bit of time investigating. Today I pulled the wire off coil 6 and it seems the noise has gone away. Car was warm by the time I had played around with it so going to wait until tomorrow morning and start it again, see if the noise is still gone.

I heard a pretty good explanation of the actual sound the other day - like when you sit a playing card in the spokes of a push bike - pretty close to that.

So - does it sound like a spun bearing to you?

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not really....and I've heard a few.

does it get louder with revs going up and quieter with revs going down?

in any case if you think its got a bearing spun you should not be running it more than a few seconds, the longer you run it the more shit gets through the motor

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its very possible. check youtube for other spun bearings and compare to yours.

try avoid running it much more. get the sump off and replace the bearings. you might be lucky that it hasnt damaged the vrank yet. and might be just a quick r+r.

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Hmm well I would definitely love to be wrong. It has been running like this for months - probably a good few thousand kms.

Duncan - it does get louder from 2500 to 3500 but then the noise seems to go away.

Dave - I did grab each injector while it was running and #6 didn't seem any different - but I will investigate further - I guess disconnecting #6 injector wont really help me any further with my diagnosis - would need to move it to another cylinder. Of course I threw out my old R32 injectors over the weekend - some of them were leaking but could have come up with at least one good one.

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oh yeah should have said....it sounds like a gnome hammering on your crank...not a card in the spokes :)

if you want to be sure and have no rush you could get the oil analysed, will tell you for sure if you have a bearing issue

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Yeah its funny how it does it for about 1 second when first start dead cold only. This is what lead me to believe it was a bearing as the oil would have all drained out.

Its not like a normal injector ticking noise - its quite audible within the cabin, quite metalic sounding.

RE: Lifter noise - forgive my ignorance but the rb26 being a bucket and shim valve setup - are there any lifters??

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theres no lifters, but there can be excessive clearance in the shims, but its constant,

just start getting some prices together, you have to pull the motor out either way by the sounds of it, now the debate whether you get a 2nd handy or fix your current motor with the option of a rebuild

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I just went out and had another listen - it really isn't like any of the others I looked up on youtube. They are all BANG BANG BANG BANG, this is nowhere near as loud.

Will have a play with the injectors tomorrow - this was my initial guess.

Duncan - who does oil analysing up your way?

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just start getting some prices together, you have to pull the motor out either way by the sounds of it, now the debate whether you get a 2nd handy or fix your current motor with the option of a rebuild

Got a bit of a quote from Racepace a while back before Ben sold up - $15k for the whole shabang N1 block, 33 crank etc etc out and back in - wonder if Chris has adjusted the price structure!! End of the day this is going to be the best route - was going to do it eventually but thought I may as well have a bit of fun with this mill until the inevitable happened.

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sorry to be the one to disagree, but your description is spot on to every big end ive ever heard.

now if people are nit picking to a spun bearing vs a worn bearing i dont know, but card in the spokes and your description of 2500 to 3500 is exactly consistant to the many bearings ive heard.

thats the sound of an early days big ender, for all you know, it could still be savable.... best bet, drop the sump and check number 6 :)

im 100% sure noone will agree with me here, but I have actually had success in the past where this has happened to the extent yours has, we have isolated the cylinder like you have, and matched a new bearing to it without machining and the motor lived on forever more.

so GL

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I had a 180sx which had a light taping noise very much like you are describing after lots of looking and listening I eventually did a compression test and found it was cracked ring lands on the rear cylinder. It was hardly noticable aside from a slight drop in boost and the idle was a tiny bit rough- just a smidge.

I hope it isn't that in your case-good luck with it.

Cheers.

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Cheers Scott - yeah I have read in my research of people with a similar sound running for a few months without a problem until they fail properly, problem ending up being a big end bearing.

Wont bother starting it again and get it to someone that knows that they are doing!

I wish it was an easy exercise to drop the sump on a 26 - have never attempted it myself but I think regardless its an engine out.

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Before you do anything drastic pull the oil filter off and open it up with a tin opener or chisel and look for bearing materials -little specs of copper coloured material. Next I would do comp and leak down check to make sure you havnt delaminated a piston crown. If all is healthy then it may have shrunk a skirt - but it's not a common problem on these engines.

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From this section of your original post:

"Today I pulled the wire off coil 6 and it seems the noise has gone away"

The noise would be constant - It wouldn't go away if you pulled coil no 6. Your crank will spin regardless of the coil being attached its one piece, hence the noise should still be there.

I would imagine a big end would give up or at least get worse once it lets go, that fact you have driven thousands of k's since indicates the problem is not a big end...

Just some fuel for the fire...

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Yeah I guess the theory is if the cylinder isnt firing it isnt going to be loading up on the crank, less loading on the bad bearing and so less noise.

I gave it another kick in the pants this morning from dead cold, with no 6 coil disconnected and it still made the noise although somewhat more muffled. Going to try disconnecting the #6 injector tonight from dead cold and see how I go.

God I really do hope its just an injector dying - the one on #6 was actually flowing a little higher than the other 5 in cleaning/testing before I put them in. #6 plug is perfect however, no leaning or fouling.

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