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Sau Lend Me Your Ears! Rb25 Noise

gotRICE?

By gotRICE?,
in Engines & Forced Induction

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GTScotT Grand Master

GTScotT

Posted
Posted

being dependant on temperature i would point the finger at an internal component of the motor.

what I would so is, I would invest in a torque wrench and drop the sump and check the condition of your big end bearings one at a time. I rekon you will find one is minorly eaten away.. and once at opperating temperature the bearing expands ever so slightly and closes the gap enough for the oil to shut it up.

Only speculating really... checking the bearings is as cheap as buying a tool you really should have anyway and plus you get to have a good look at the condition of the bottom end anyway...

seeing as the sound is so minor, IF it is a bearing thats slightly worn.. a new set of nissan bearings for around 100 bucks will see your motor back to full health and no noise. obviously if it is a bearing, being so slight it wouldnt have damaged the crank (we hope) BUT leaving it could create bigger issues if you ever had an oil or temperature related stuff up when giving it a hard time.

better safe than sorry, id atleast check :)

The Dan Grand Master

The Dan

Posted
Posted
what I would so is, I would invest in a torque wrench and drop the sump and check the condition of your big end bearings one at a time. I rekon you will find one is minorly eaten away.. and once at opperating temperature the bearing expands ever so slightly and closes the gap enough for the oil to shut it up.

sounds like there is a rofl in your copter

The Dan Grand Master

The Dan

Posted
Posted
you think its a shit idea? care to explain?

It's not a shit idea. If there is an engine noise and he has exhausted all other possibilities, then yes, that is what you would do.

What I was referring to was your comment on a bearing being 'minorly eaten out' and the concept of bearings expanding that much when hot.

Bearings don't get minorly eaten out and they do expand but at around 80-100 degrees it is microscopic.

If there is engine bearing damage, it's not always as easy as just throwing in a new set and away you go.

The Dan Grand Master

The Dan

Posted
Posted

The noise this guy posted up is coming from behind the timing cover. It is 150% not an internal engine noise.

Change the timing belt, water pump and timing belt bearings.

It is also possible the noise is coming from the CAS bearing so check to make sure it's not fubar.

mattymagoo22 Community Regular

mattymagoo22

Posted
Posted

When I replaced the timing belt on my car it had a noise very similar to that, it was an after-market item I replaced it with. I got a genuine belt and did the job over and the noise was gone. Its too hard to say without being at the car exactly what it is.

Cheers.

GTScotT Grand Master

GTScotT

Posted
Posted
It's not a shit idea. If there is an engine noise and he has exhausted all other possibilities, then yes, that is what you would do.

What I was referring to was your comment on a bearing being 'minorly eaten out' and the concept of bearings expanding that much when hot.

Bearings don't get minorly eaten out and they do expand but at around 80-100 degrees it is microscopic.

If there is engine bearing damage, it's not always as easy as just throwing in a new set and away you go.

being a minor noise if it were a bearing i would be hoping to find its missing abit of white meat but nothing too major. in which case id be willing to take the punt on a new set of bearings. my comment did leave enough to the imagination to assume if he found the bearing had marked the crank he obviously wouldnt chuck in a new set of bearings.

and your right, "it's not always as easy as just throwing in a new set and away you go." whats the worst that could happen anyway? need to redo it properly? heaven forbid....

and im fairly sure a bearing doesnt take long to hit 100 degrees and open up that microscopic unit before it can overcome whatever deformity it has formed and allow decent oil flow. but as stated, im only speculating and in doing so im thinking in extremes rather than hopes. but hey im no mechanic, i actually know realistically nothing about engines.

yet I agree with you on the waterpump. If that hasnt been done id do that next along with an inspection of the bearings. for the waterpump id let the thing sit dead cold overnight and take off all the aux belts (altenator AC waterpump) then start the thing for a SHORT period to see if it will make the noise. No longer than say 30 seconds tho..

mattymagoo22 Community Regular

mattymagoo22

Posted
Posted
being a minor noise if it were a bearing i would be hoping to find its missing abit of white meat but nothing too major. in which case id be willing to take the punt on a new set of bearings. my comment did leave enough to the imagination to assume if he found the bearing had marked the crank he obviously wouldnt chuck in a new set of bearings.

and your right, "it's not always as easy as just throwing in a new set and away you go." whats the worst that could happen anyway? need to redo it properly? heaven forbid....

and im fairly sure a bearing doesnt take long to hit 100 degrees and open up that microscopic unit before it can overcome whatever deformity it has formed and allow decent oil flow. but as stated, im only speculating and in doing so im thinking in extremes rather than hopes. but hey im no mechanic, i actually know realistically nothing about engines.

yet I agree with you on the waterpump. If that hasnt been done id do that next along with an inspection of the bearings. for the waterpump id let the thing sit dead cold overnight and take off all the aux belts (altenator AC waterpump) then start the thing for a SHORT period to see if it will make the noise. No longer than say 30 seconds tho..

Its a nice idea but does sort of sound like jumping in at the deep end. In my experience by the time you hear a big end its too late for the crank as the big end bearing journals are already scuffed and the rod in some instances can be damaged too. If it was a datto 200B or a KE70 corolla you could try a bit of wet and dry on the journal and slap it back up together with oversized bearing shells and it would probably be right as rain.

I recently saw brand new short motors from a well know and loved manufacturer that had not even been started and when pulled down and inspected the big end shells and crank journals were already marked hence the shells being replaced with a new item containing lead as they were trying to get away from using it. Sad really Lead and Asbestos 2 great gifts to the automotive world that caused some many more problems then we knew.

Cheers.

The Dan Grand Master

The Dan

Posted
Posted
Without reading anything i would say it sounds like the crank takes a walk in the main bearings :)

And you'd be wrong.

Not only that but do you know how much damage would occur if the crank could actually move on the main bearings. He would notice a massive drop in oil pressure, the thrust bearing would disintegrate and would have a knock, not a whirring humming noise.

Until this guy checks out the things I said originally, the noise is going to stay there. If he doesn't change those things soon enough, it could fail.

gotRICE? Veteran

gotRICE?

Posted
  • Author
Posted (edited)
And you'd be wrong.

Not only that but do you know how much damage would occur if the crank could actually move on the main bearings. He would notice a massive drop in oil pressure, the thrust bearing would disintegrate and would have a knock, not a whirring humming noise.

Until this guy checks out the things I said originally, the noise is going to stay there. If he doesn't change those things soon enough, it could fail.

Yeah, it scares me too. But at this time of year its a bit of a struggle to get anything done.

Funny though, iv had the car coming up two years and its done it since day one that i can recall.

I will get the parts i have swapped over etc and will report back as soon as i do. Hopefully with good news :)

Was there anything else i should change that COULD be causing the then noise while im at it?

Currently have

Waterpump

Tensioners

All Belts

Seals

I guess before i start i could try whipping the belts of temporarily too, just incase its some random pulley.

Edited by gotRICE?
Lukas 33 Proficient

Lukas 33

Posted
Posted

My car was making some bullshit noise like that about 4 weeks ago. I just replaced the idler, tensioner, timing belt and water pump and viola all gone. BUT Im not saying that's the issue.

Simon-S14 Grand Master

Simon-S14

Posted
Posted

yup. i had the same noise. Its quite common on RB's and really the tension of the timing belt has to be spot on... too loose and it makes this noise or too tight and it can cause other issues.

all i did to fix mine was tension up the belt a bit more and away i went, was a brand new belt anyway so replacement wasnt needed but in your case you have a belt. chuck the kit in and be done with it

eightsixboy Mentor

eightsixboy

Posted
Posted

Sounds like belt slap or something, like your timing belt is loose. I doubt its internal, piston slap is a completly different noise and bearing noise is normally fairly obvious. If it were a big end i dare say it would have gotten a lot worse by now.

I'd check to see how old the timing belt is and either replace it or atleast retention the old belt with a new tensioner. If the waterpump looks ok (ie doesn't have play in the bearing) then when all the accessory belts are off maybe run the motor and see if it still does it.

gotRICE? Veteran

gotRICE?

Posted
  • Author
Posted (edited)

Well as i said id update this after i had a play..

Decided on the 30th to man up and have a go at changing the cambelt. I consider myself relatively mechanically minded but havent ever attempted a cambelt before.

Read through a tutorial on here a while back so went at it on memory haha. Not overly confident so had a mechanic friend looking over my shoulder at points i was uneasy about.

Cut a 6 hour story short (alot of questions, and getting the harmonic balancer puller to work properly) i had success with nothing broken!

Noise has been eliminated. Win ++

Parts i changed were:

Cambelt

Waterpump

Idler Pulley

Tensioner Pulley

PS Belt

AC Belt

Alternator Belt

Im not 100% sure of what actually cured the problem. I did notice that there was a little slack in the cambelt. Maybe it was this? Maybe it was a dodgy idler? Or Tensioner?

After reinstalling the radiator and bleeding the system, i realised that i had forgotten to change some oil seals that came with the kit.. a case of out of sight out of mind. They were in the glovebox after me finding them floating around in the boot :P Didnt have any leaks, so heres hoping they hold out untill the next belt change.... :geek:

Either way its fixed. One more thing to cross off the list of things to do before i die.

Edited by gotRICE?

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