Tapping/knocking Noise From Rb26

[Angus Smart]

I've got a knocking noise, i've done a compression test and came up with 140ish across all cyl with cyl 2 @ 138 just a little below but not a worry, so head gasket fine etc..

i've tried disconnecting 1 coil at a time to see if it goes away. checking if it is cylinder or rod related.

i've taken the fan off timing belt covers tried all this to check if there is a problem of noise coming from either.

is there anyway i can check main bearings without pulling the c**t apart? or anything else someone can recommend?

cheers

Andrew

[The Mafia]

probably pull the sump off and have a look.

Or maybe a bore scope stuck in somewhere?

Where does it make the sound?

[GTR1993]

Is the noise dependant on revs? Louder when hot or cold etc?

[Beer Baron]

well you can't just 'pull the sump off', that needs the engine to be out of the car for that to happen so it's pretty $$$ if you aren't doing it yourself.

what is the oil pressure like? use your defi controller to record 3 mins of hard driving and see what it's doing under different circumstances.

[wrxhoon]

Nothing you can do to check bearings unless you pull the sump off and to do this, although possible with the engine in the car , its much easier with the engine out . If you are concerned about bottom end ( usualy big end bearings) take it to any good mechanic, let him listen to the sound and he should be able to tell you what it is .

When you pick up on a bearing you can hear this tapping like sound, it could sound like coming from the cyl head and you may think its lifter noise. It will be much quiter when the engine is cold and gets louder as the oil temp rises , when you are about to spin a bearing( or if one or more have spun) it will be unbearably lould, in this case you shouldn't drive it because you will end up with a rod out of the side of the block. Another way to listen to this, is while driving in a tunnel or a rockwall on at least one side of the road with a window down you will hear it . If you diagnose it as bearing noise by then more than likely the crank will need machining, if you let it go until you spin a bearing the crank will need replacing, either way you will be for a full re-built while the motor is out .

Compression has nothing to do with scored or spun bearings, compression will only tell you how good your bore, pistons, rings, headgasket and valves seal and a lot of the time not even that because oil will seal worn bore/rings but not worn valves or leaking H/G. A leak-down test is more comprehensive for this, as well as as a comp test .

[mid life crisis]

you can put a big arse screwdriver or buy a cheap stethascope from super cheap or the likes start the motor and but the screwdriver or scope agaist diffrent parts to the block with ya ear on the end of the screwdriver to determine where the noise is comming from . might give more of a idea if it;s from the bottom or the top of the engine

[Angus Smart]

Nothing you can do to check bearings unless you pull the sump off and to do this, although possible with the engine in the car , its much easier with the engine out . If you are concerned about bottom end ( usualy big end bearings) take it to any good mechanic, let him listen to the sound and he should be able to tell you what it is .

When you pick up on a bearing you can hear this tapping like sound, it could sound like coming from the cyl head and you may think its lifter noise. It will be much quiter when the engine is cold and gets louder as the oil temp rises , when you are about to spin a bearing( or if one or more have spun) it will be unbearably lould, in this case you shouldn't drive it because you will end up with a rod out of the side of the block. Another way to listen to this, is while driving in a tunnel or a rockwall on at least one side of the road with a window down you will hear it . If you diagnose it as bearing noise by then more than likely the crank will need machining, if you let it go until you spin a bearing the crank will need replacing, either way you will be for a full re-built while the motor is out .

Compression has nothing to do with scored or spun bearings, compression will only tell you how good your bore, pistons, rings, headgasket and valves seal and a lot of the time not even that because oil will seal worn bore/rings but not worn valves or leaking H/G. A leak-down test is more comprehensive for this, as well as as a comp test .

yeah i just wanted to cancel out the headgasket so i did the compression test. but again i'm not too keen on taking it for a drive as i may cause more damage.

well you can't just 'pull the sump off', that needs the engine to be out of the car for that to happen so it's pretty $$$ if you aren't doing it yourself.

what is the oil pressure like? use your defi controller to record 3 mins of hard driving and see what it's doing under different circumstances.

oil pressure is fine, defi says up to 8 on cold and drops to 6-3ish when warm after a good drive, tho i dont want to drive it anymore caus of the knocking..

i've used a screw driver and ear business against the water pump, ac, all over the head. i beleive its coming from the bottom end..

[wrxhoon]

When big ends go its usualy number 6 that goes first ( of course it can be any other ) if this is the case with yours you should be able to hear the tapping like coming from the bellhousing.

BB you can have picked up bearings in an RB 26 and still have good oil pressure, I have even seen one with a spun bearing and still holding good oil pressure.

[Angus Smart]

haha well with a 34 gearbox in this thing there is an abundance of tapping near the bell housing its impossible to hear anything under there.

i took it to my friends shop, did an oil change, put it on hoist. he had difficulty listening for noises too.

said pulleys are very noisy and i should get some new ones first before i worry about the rest.

[wrxhoon]

haha well with a 34 gearbox in this thing there is an abundance of tapping near the bell housing its impossible to hear anything under there.

i took it to my friends shop, did an oil change, put it on hoist. he had difficulty listening for noises too.

said pulleys are very noisy and i should get some new ones first before i worry about the rest.

Why would a 34 g/box make it any noisier than the 5 speed 32 box? Pulley noise is very different to a tapping noise, if he can't hear any noise keep driving it , if its a bearing it will get louder soon enough.

[Angus Smart]

maybe my bearing in my gearbox is also bad, but since i've put the 34 box in i get the loud rattle on idle, apparently its normal when not using dual mass flywheel?? so its rather noisy under the car while up on the hoist at idle...

i'll get the pulleys sorted and go from there. will call autosport today

[wrxhoon]

maybe my bearing in my gearbox is also bad, but since i've put the 34 box in i get the loud rattle on idle, apparently its normal when not using dual mass flywheel?? so its rather noisy under the car while up on the hoist at idle...

i'll get the pulleys sorted and go from there. will call autosport today

The rattle you can hear is more than likely your clutch, what kind of clutch have you got ? Does it go away if you push the cluth in? You souldn't have any cluth box rattles when under load , check it out while driding with the window open on a cutting/tunnel. Gearbox bearings don't make tattling sounds the make winding like sounds, I guess with all the tattling and exhaust noise its hard to defferenciate .

[Angus Smart]

yeah goes away when clutch is pressed in and is only on idle. its not really a great concern of mine.

os 3 or 4 plate, i didnt actually see the clutch before it went in.

we're booked in to autosport so i should have it sorted by the time i get back from America

[wrxhoon]

os 3 or 4 plate, i didnt actually see the clutch before it went in.

This is where the rattle comes from, multi plates will rattle when not under load . Why not push the clutch in while you are listening to the tapping noise? You should be able to isolate it from the front pulleys that have winding bearing noise, toataly different to either lifter of big end bearing sound.

[Angus Smart]

by rattle do you happen to mean a slapping banging metal sound?? but yes it does go away while clutch pedal is pressed..

i dont seem to have oil pressure problems, it hasnt dropped at all and stays very constant while driving. engine has been rebuilt before by the looks of it too. as i have n1 pistons in a standard block.. and also pushing around 450hp at the wheels.. after the oil change the other day it seems to be fine..

i should show you my box noises one day. i've not herd a 34gtr make this noise before. and i've driven plenty with aftermarket multi plate clutches..

could also factor in i have nismo spline too.

[justin911]

isnt the tapping in the clutch the fork thing sometimes ? mine used to do it. clutch was fine though.

[wrxhoon]

by rattle do you happen to mean a slapping banging metal sound?? but yes it does go away while clutch pedal is pressed..

i dont seem to have oil pressure problems, it hasnt dropped at all and stays very constant while driving. engine has been rebuilt before by the looks of it too. as i have n1 pistons in a standard block.. and also pushing around 450hp at the wheels.. after the oil change the other day it seems to be fine..

i should show you my box noises one day. i've not herd a 34gtr make this noise before. and i've driven plenty with aftermarket multi plate clutches..

could also factor in i have nismo spline too.

Yes thats what I mean, if it goes away when the clutch is in thats the sound of the clutch plates rattling, nothing to worry about . Nismo spline shouldn't make any difference.

Just because the engine was re-built at some stage doesn't mean the bearings are not your issue . I have seen plenty of newly built engines with bearing issues .How do you know you have N1 pistons? Do you mean the tapping noise went after the oil change ?

[Angus Smart]

Yes thats what I mean, if it goes away when the clutch is in thats the sound of the clutch plates rattling, nothing to worry about . Nismo spline shouldn't make any difference.

Just because the engine was re-built at some stage doesn't mean the bearings are not your issue . I have seen plenty of newly built engines with bearing issues .How do you know you have N1 pistons? Do you mean the tapping noise went after the oil change ?

my friend said he couldnt hear any definate signs of bearing problems. we then did an oil change, and that was that.. between the noises of the pulleys my crank pulley that looks a little out of balance, and the gearbox sounds. said its probably the pulleys that have thrown me off thinking its running like shit. feeling vibratons etc..

yeah i understand the rebuild could spell problems still. just making a note that its been done..

when i could read the top of the pistons they had a different stamp than the normal 05u on top.. i beleive it was aa something.. i've forgotten..

[wrxhoon]

my friend said he couldnt hear any definate signs of bearing problems. we then did an oil change, and that was that.. between the noises of the pulleys my crank pulley that looks a little out of balance, and the gearbox sounds. said its probably the pulleys that have thrown me off thinking its running like shit. feeling vibratons etc..

yeah i understand the rebuild could spell problems still. just making a note that its been done..

when i could read the top of the pistons they had a different stamp than the normal 05u on top.. i beleive it was aa something.. i've forgotten..

By crank pulley I assume you are talking about the harmonic balancer, that shouldn't be noisy , it bolts on the crank and turns with it . If its out of balance you should replace it asap, if the whole crank/rod/piston assembly is out of balance you have bigger problems. If any of these are out of balance that could be the problem but they wouldn't create a tapping like sound. It would be more like vibrations rattle in the clutch/box . Have a good look at the h/balancer to make sure its not chiped or cracked .

You could have aftermarket pistons, maybe forged , do they rattle on cold starts?

[Beer Baron]

yes if your crank pulley (aka harmonic balancer) is 'out of balance' and noisy then my advice is very simple. start saving.

check your balance bolt is done up tight, as it comes loose it will make a noise which sounds like a bearing is stuffed in the PS pump or something. it wont take long for the balancer to wreck the keyway it's located on, and if you are really unluckly things only get worse from there.