Rattle In Engine - 'spun A Bearing'? What The?

[dan.1337]

I've got this rattle in my engine and my mechanic says I've 'spun a bearing'.

It still drives fine and all, but he also mentioned that I shouldn't push it too hard due to this problem.

Can anyone enlighten me further on what could have happened?

Thanks in advance!

[mad082]

you have just discovered the true meaning of 'RB'. 'Runs Bearings'

[InterCooL]

could have damaged a bearing where it has been grabbed by an adjacent surface, causing metal on metal wear, sending particles of metal throughout your engine. could have destroyed oil galleries, pump, and any and every bearing

on the other hand i've been told you can just get a 'noisey bearing' which just needs to be replaced.

so your engine may need to be replaced or rebuilt. or just a bearing needs to be replaced. an experienced mechanic should be able to tell you once they pull your engine apart.

drop your sump off and look for metal filings everywhere. if you have them everywhere then there's a good chance you can say goodbye to your engine

[dan.1337]

Awesome (not really), but i'll ask him about it tomorrow morning when I pick my car up.

So it sounds like a pretty commong problem?

[Simon-S14]

its common in situations where the oil pump is failing/weak, or theres a drop in pressure via a surge or something like that, soon as theres no oil pressure the bearings grab and spin... by by bottom end

[dan.1337]

Doesn't sound good at all =(

Does this mean that I should stop driving it? Or because it's on death row, I should start looking for a new engine and keep on rollin' till it stops? I'm just not a big fan of the idea of my car stopping in the middle of somewhere. Usually I drive around because I need to get from A-B and not because i'm cruising around for the hell of it.

[Adriano]

Stop driving it, rip the sump off and see what the problem is. I doubt the bearing has spun, engines only last minutes after they spin, its probably just shagged. You may be able to get away with replacing the big end bearings if the crank isnt damaged, thats what i did in my z32 300zx, it was a bit noisy whan i got it , fitted new bearings checked the clearances and drove it for a year before i sold it.

[dan.1337]

Reading up a bit more on the bearings, i'm assuming that they're 'big bearings' and if possible to be replaced, i can probably use the ACL ones listed in this page?:

http://www.aclperformance.com.au/NissanRB20DETBearings.htm

What is involved in changing the bearings? Does the engine need to come out?

[Beer Baron]

if the engine truly has spun a bearing it will last for probably 30 seconds. what happens is an engine problem (lack of oil, detonation, something) causes an event which ends in sudden bearing wear, then instead of staying in it's place the bearing grabs on the crank and it now spins with the crank. when this happens it's destroyed in a matter of seconds. when it's destroyed the crank is now spinning out of balance which causes other bearings to be destroyed. then the crank can seize and engine will stop, or sometimes it will cause a piston to break, or a rod to bend and possibly put a hole in the side of the block. I would say what has happened is you have worn bearing(s) which is causing bearing noise. if you stop driving it now and pull the engine apart you may get away with just replacing the main bearings and big end bearings. if you continue driving it the motor will be f**ked.

[dan.1337]

if the engine truly has spun a bearing it will last for probably 30 seconds. what happens is an engine problem (lack of oil, detonation, something) causes an event which ends in sudden bearing wear, then instead of staying in it's place the bearing grabs on the crank and it now spins with the crank. when this happens it's destroyed in a matter of seconds. when it's destroyed the crank is now spinning out of balance which causes other bearings to be destroyed. then the crank can seize and engine will stop, or sometimes it will cause a piston to break, or a rod to bend and possibly put a hole in the side of the block. I would say what has happened is you have worn bearing(s) which is causing bearing noise. if you stop driving it now and pull the engine apart you may get away with just replacing the main bearings and big end bearings. if you continue driving it the motor will be f**ked.

thanks for that

i'll find out tomorrow first thing in the morning whether i should drive my car to work (50km round trip) from my mechanic. if he says that its better not to, i'll see if the motor can still be saved without too much of a headache =|

what a moneypit...

[TurboX]

Had a similar problem - it was the screws on the back plate of the oil pump had come out and I assumed it was a faulty sender until it stated knocking.

Drove it for two months though and only admitted defeat when on Sams dyno (still making power - not his fault!) and had to get Jack to truck it home.

Unless you have the DIY skills and a few spare RB20's like I had, better not drive it unless you have deep pockets.

Although you can pick up a RB20 for $300 if you look around!

[SECURITY]

ive driven cars for a few weeks with a spun bearing. it will still drive like normal but it will eventually f**k things up further for you. rb20's are cheap these days, so it will probably be cheaper to replace the whole motor.

also, spinning a bearing isnt always as simply fixed as it seems. you need to check for clearances before wacking in a new set of bearings.

and it is possible to do the bearings while the motor is still in the car. i recommend getting your oil pump replaced to something like an rb25 pump with a crank collar too.

Edited August 7, 2007 by SECUR1TY

[mad082]

ask ucd15r33 about the spun bearing in his ute. i posted a pic of the result in the general discussion forum. he drove it for a few days, did some skids, rev the ring out of it, then it let go on his way home and threw a leg out the side of the block. still did a skid on 3 cylinders though.

[Simon-S14]

yeah ive driven around for a week or so with 2 spun bearings lol.

However the more you run the engine with a spun bearing the more damage it does to other componants... you can kiss the crank and con rods good buy if you persits to drive it.

however since its a 20... ditch your bottom end and get another block dirt cheap from a wreakers/on forums and be done with it

[dan.1337]

I still don't understand how my mechanic knows its a spun bearing. The car doesn't seem to drive any differently and i can't seem to pick anything that sounds different either.

Is there a sure fire way to tell without stripping down the engine?

[Simon-S14]

if its rattling in the bottom then no... theres no way of telling what it is til you strip it down.

However make sure the rattle is in the bottom end and no the head, cause that could be something else all together

[dan.1337]

he said it's right down the very back and i can't hear it from inside the car, but the motor is losing comp from it. if it were to be rebuilt, the engine would need to come out, crank remachined and all this other stuff. basically it was cheaper and less work to get another motor in.

i can't hear any obvious rattle, but then again i'm n00b and don't know what to keep an ear out for. i'm thinking of getting a second opinion to be sure to be sure before jumping into anymore expensive work.

[Duncan]

well its not really a rattle, more like a bunch of gnomes with hammers that hammer quicker as the revs rise - a good mechanic will pick the noise if they have heard it often enough.

As everyone else said, rb20s are cheap - just grab a new (second hand) bottom end. Rebuild will cost $000s once you include assembly, disassembly and all the bottom end testing and machining

[Adriano]

well its not really a rattle, more like a bunch of gnomes with hammers that hammer quicker as the revs rise - a good mechanic will pick the noise if they have heard it often enough.

As everyone else said, rb20s are cheap - just grab a new (second hand) bottom end. Rebuild will cost $000s once you include assembly, disassembly and all the bottom end testing and machining

Depends, im assuming you are paying foe labour. It shouldnt cost more than $3-400 to get teh sump ripped off and the bigend bearing clearances checked, im betting one will be loose, and if you cant here the noise, new shells will probably fix it, if not dont put the bottom end back together, just chuck a motor in. Either way its not going to be a particularly cheap exercise.

[dan.1337]

well its not really a rattle, more like a bunch of gnomes with hammers that hammer quicker as the revs rise - a good mechanic will pick the noise if they have heard it often enough.

As everyone else said, rb20s are cheap - just grab a new (second hand) bottom end. Rebuild will cost $000s once you include assembly, disassembly and all the bottom end testing and machining

this noise you've mentioned, is it meant to be loud and obvious or quite quiet??

also, when a bearing is spun, does the car start to lose compression and hunt on idle like when the AAC valve is blocked?