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chapterone

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Discussion starter · #1 ·
I'm having my engine rebuilt after no.2 bearing went, has cause slight damage to crank, light ripples on no.2 only. Have had advice that it may only need polishing out, also I thought regrinding might have been an option but consensus on here seems to be to avoid at all costs, anybody with more advice, experience or words of wisdom would be muchly appreciated!

Hoping to have more of an idea of what I should/shouldn't do before the guys at the garage call this week

Also what's the additional costs of a new crank if that is the only option?

Thanks in advance for any and all help!

Neil :nailbiting
 
Avoid grinding at all cost, most engines rebuilt with a ground crank fail.
Now whether its the grinding that actually causes them to fail, or the abuse they get while the damage is being done to the crank originally is something I for one cannot say.
 
please do not fit a reground crank
 
All of the above Neil ^^
If you can get away with the journal being polished and it's within tolerances that's the only way to go IMO.
Make sure you rebuild with ACL bearings, ARP bolts and the oil seal mod :!:
 
Discussion starter · #5 ·
Cheers, general consensus...avoid like the plague then! Here's hoping there's not to much damage, and I don't need to add a new crank to the cost!

Better to know now about not regrinding and replace it, than later on when it goes south again!

Cheers all, will post an update once I know more!
 
chapterone said:
Cheers, general consensus...avoid like the plague then! Here's hoping there's not to much damage, and I don't need to add a new crank to the cost!

Better to know now about not regrinding and replace it, than later on when it goes south again!

Cheers all, will post an update once I know more!
Aye mate as you don't want to go through this experience and cost ever again :adminfinger
 
good call and wise choice
 
pdfisher said:
good call and wise choice
'Do it once, do it right' :thumbright:
 
i followed woz and his advice 4 years ago and got my truck sorted buy billcar
ive had 4 years of trouble free motoring
and my truck is not for sale its a good old girl and will last for years
thanks to advice gained from this forum
good luck with yours
 
Just to add my own thoughts on your question.
No one has ever heard a classic big end knock on a D22, they go from running, to complete failure extremely quickly, almost instantly, I think this is due to very small excess clearances in the ends setting up resonances and vibrations that adversely affect the metalurgy of the con rods and their bolts.
I wrote the piece below in response to another member who was thinking of using a used crankshaft, as Woz has already said measure the clearances and measure again, make sure of your accuracy, if after polishing the dimensions are anywhere near the upper wear limits, personally I would scrap the crank.
As before just my thoughts written and meant in good faith.

"The one thing you need to be VERY wary of, is big end bearing clearances that are nearing the upper limits.
Not only are the original shells, con rod bolts and sump to oil pump seal badly designed and specified, but the con rods themselves have a built in weakness also, THANK you again Nissan!
There is an oil-way drilling on the neck of the upper part of the con rods, that has a tendency to be the starting point of disasterous cracking leading to complete engine failure, usually throwing the rod through the block.
Obviously this does not occur on engines with close end bearing clearances, and usually shows up once the big end cancer has been discovered, sometimes the conrod is still in place BUT with a cracked neck!
I can only presume that the start of this cracking is due to micro vibrations and hammering caused by the end shells having been worn allowing too much movement causing metal fatigue leading to failure.
So my humble advice to you is, if there is ANY wear evident on the used crankshaft pins I would NOT be using it, spend a little extra for a new one of good manufacture, at all costs you need to save the block."
 
Discussion starter · #12 ·
chris vince said:
Just to add my own thoughts on your question.
No one has ever heard a classic big end knock on a D22, they go from running, to complete failure extremely quickly, almost instantly, I think this is due to very small excess clearances in the ends setting up resonances and vibrations that adversely affect the metalurgy of the con rods and their bolts.
I wrote the piece below in response to another member who was thinking of using a used crankshaft, as Woz has already said measure the clearances and measure again, make sure of your accuracy, if after polishing the dimensions are anywhere near the upper wear limits, personally I would scrap the crank."

Fortunately I caught mine at the knocking phase, well at least no noise then loud knocking and no.2 shell broken but no serious damage, and no con rod through the block, I've been one of the lucky ones by all reports! At least that's the way I'm looking at it!

It might be of interest for anyone who hasn't had the upgrade or problem yet, I noticed a distinct difference in the idle 'wobble/vibrations' (for want of a better word) running through the truck a day or two before the knocking began, I link the two in the loosest sense as it was so close together, but guess it was the slight change in the shell shape/crack appearing causing excess vibrations, it might just help somebody catch a problem early!

Again all great advice so massive thanks, just out of my own interest, as I've got a specialist engine company doing the work, where would I find the info for the clearances or how do you go about testing them? "Curiosity killed the cat moment"

Thanks
Neil
 
chapterone said:
chris vince said:
Just to add my own thoughts on your question.
No one has ever heard a classic big end knock on a D22, they go from running, to complete failure extremely quickly, almost instantly, I think this is due to very small excess clearances in the ends setting up resonances and vibrations that adversely affect the metalurgy of the con rods and their bolts.
I wrote the piece below in response to another member who was thinking of using a used crankshaft, as Woz has already said measure the clearances and measure again, make sure of your accuracy, if after polishing the dimensions are anywhere near the upper wear limits, personally I would scrap the crank."

Fortunately I caught mine at the knocking phase, well at least no noise then loud knocking and no.2 shell broken but no serious damage, and no con rod through the block, I've been one of the lucky ones by all reports! At least that's the way I'm looking at it!

It might be of interest for anyone who hasn't had the upgrade or problem yet, I noticed a distinct difference in the idle 'wobble/vibrations' (for want of a better word) running through the truck a day or two before the knocking began, I link the two in the loosest sense as it was so close together, but guess it was the slight change in the shell shape/crack appearing causing excess vibrations, it might just help somebody catch a problem early!

Again all great advice so massive thanks, just out of my own interest, as I've got a specialist engine company doing the work, where would I find the info for the clearances or how do you go about testing them? "Curiosity killed the cat moment"

Thanks
Neil
Here you go (click the image to expand)
Ignore the re-grind stats :bom:
[attachment=0:285fwn93]YD25 crankshaft data.PNG[/attachment:285fwn93]
 

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chapterone said:
Cheers woz, wow can see why regrinding really isn't an option, those tolerances are tight!
Re; your reply above, that is why you must be very careful 'polishing' the crankpin.
Introducing any excess clearances, or wear for want of a plain description must be avoided, these engines DEMAND close fitting big ends!
I am NOT trying to teach anyone to suck eggs, OR knocking any good engineers out there, but it needs to be said.
Forget thinking the YD25DDTi is just another diesel engine!
These engines, thanks to cost cutting morons in Nissan and Renault built these engines (and still do (single row timing chains in the D40's!) with latent catastrophic defects, from new they are like time bombs waiting to explode.
Whoever rebuilds these engines MUST know them inside out and NOT cut any corners whatsoever.
If(?) built correctly the D22 will be a reliable joy to own (very little else goes generically wrong with them), but if corners are cut and they are put together incompetently, or with cheap parts, they are little better than when new, and will let go, sooner rather than later.
There is plenty of evidence on here to back this statement up!
Respectfully, I would suggest you spend and evening just reading through the threads on 'blown engine', 'engine modifications' etc etc, have paper and pen handy to write down relevant information, part numbers, contact details etc.
Learn as much as you can about this problem and pass this information onto your engineers.
IMHO, I have said this before but I would fit the original end shells I sourced some 7 years ago, the ones that need the tangs filing (any engineer is more than capable of this) this will give you nearly 1mm more bearing width (on an already skinny bearing!), as they say "every little helps"!
Always remember that the crankpins on these 2.5lt, turbo charged diesel engines are identical in size, to a 1.4lt normally aspirated petrol engine that ceased production in 1970!
For that is where (with the excellent help of Bruce Williams at ACL) we discovered the lead/copper bearings that would fit this engine.
As before NO offence intended to anyone, just trying to offer hard earned knowledge.
 
chris vince said:
Just to add my own thoughts on your question.
No one has ever heard a classic big end knock on a D22, they go from running, to complete failure extremely quickly, almost instantly, I think this is due to very small excess clearances in the ends setting up resonances and vibrations that adversely affect the metalurgy of the con rods and their bolts.
That's exactly what happened with mine last week.
 
Totally agree with Chris Vince and his comments :salute:
If the engineers or engine builders are not 'clued up' on these engines then take your money down the garden and burn it :slaphead
IF this engine is built correctly with the 'mods' it will be reliable and will not fail as there has not been one failed unit reported worldwide IF built correctly :!:
 
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