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Knocking sound around 3000 RPM ?

10K views 53 replies 17 participants last post by  Xanathos  
#1 · (Edited)
Hi everyone,

As you may know (or not: http://www.gtr.co.uk/forum/492857-future-r34-gt-r-v-spec-good-deal.html ) I was supposed to buy a R34 GTR.
The guy finally did the wheel alignment (check the thread above)
A new problem appeared, on his way back to home, he noticed a knock noise coming from the engine around 3000 RPM, from what he said, it disappear at higher RPM and not present on idle.

Here is a video of the noise:
https://www.youtube.com/watch?v=eBzkaT1t378&feature=youtu.be

He said he would drop the price accordingly, but to be honest, I don't wanna buy a car and spend few more k right after, if anyone would have a rough idea...
I may sound annoying because I always create threads to ask questions, but "better be safe than sorry" they said...

Thanks everyone.
 
#4 ·
if its clanking at 3k its span a bearing and took out the crank a rod and the more its ran the more will go. Its not going to fix itself and its not a quick cheap fix im afraid.
 
#41 ·
No, it's not a matter of 5k. You will need a new or a very good non ground crank if this ones has scoring- never a good idea to regrind a RB crank. Then to find out what else it has damaged, replacement parts, labour - unless you find a back street jack of all trades to do it on the cheap expect to pay 2-2.5k in removal and fitting. I'd drop the price by at least 8-9k.
 
#11 ·
Where do you think all those little fragments of bearing shell and crankshaft go? Answer - everywhere! I'd want more than ÂŁ5k off for a rebuild as I'd expect to be facing something more like ÂŁ8k to ÂŁ10k and I can't see the seller knocking that much off. I'd avoid it, there'll be others.
 
#12 ·
Where do you think all those little fragments of bearing shell and crankshaft go? Answer - everywhere! I'd want more than k off for a rebuild as I'd expect to be facing something more like k to k and I can't see the seller knocking that much off. I'd avoid it, there'll be others.
As expected, he didn't want for a 10k(€) drop, I'll look for another one, even though it is really difficult to find one in France...
 
#14 ·
To be honest, if the price drop was correct, I would be tempted to go for it and get the engine rebuilt. At least you know what's what then and you essentially get a free rebuilt engine. Would have to be a big enough discount to make it worthwhile though, and you'd need to make sure you had a mechanic around willing and able to undertake the work.
 
#19 ·
I managed to get 10k off the price, but still thinking...
Any idea what would be the range of cost?
Also somebody told him it happened because his pistons were not forged while he was running 520hp, I'm pretty sure the RB26 pistons can hold that kind of power easily without being forged (Glenn is gonna be mad for sure) the workshop which installed the mods and tuned the car is pretty reputable here, so I'm sure he knows what he was doing...
 
#20 ·
the power level wont be why its spun a bearing. probably due to oil starvation, badly contaminated oil, been over revved one time too many. could be many reasons but a healthy stock engine should be happy at that sort of power as far as internals go. i think 600bhp is where things are likely to break.
 
#21 ·
Exactly what I was thinking, workshops love to blame their rivals, typical french attitude...

Okay, here is what I was thinking, the seller lives in the nearest city in France from UK, I was thinking to make the car take the boat to UK, and let a reputable specialist (preferably in southern area) pick it, and get the job done (eventually upgrade specs as well), if anybody got clues or have contact with one of them to arrange that plan.
 
#22 ·
abbey would be my choice in your situation given there the most southern reputable specialist's i can think of. while its in bits get some good quality rods and pistons ect. i would also get the spline drive kit to eliminate any future insecurities regarding the poor oem oil drive
 
#24 · (Edited)
Yeah That's epic that you got that 10k off now get it built right. You will be able to get it sorted for 5-6k and for that you'll have a brand new block that will sing. There's a brand new unopened rb26 crankshaft for sale on here for about 850.. approx 300quid what they usually sell for.. Start there! Then you have a solid pick of pistons and rods.. so many options and opinions.. but can't go wrong with wiseco pistons 87mm and some cosworth rods. New N1 oil pump, baffled sump and you'll have a car that is spankable at 550 as a starting point lol!
As said oil starvation is a major culprit when these engines are biffed at constant high rpm... baffled sump, oil restrictor in block, head return line will def help out :)
Then of course you have a pick of turbos too [emoji14] set of gt-ss tubs or go big with 2860-5 turbos.. they're not daft and scary at all!!! [emoji38]

It's easy to just walk away but if you can be patient you'll have a tidy 34 gtr that eats 500-600bhp easily and has ample room for more should you desire. Get receipts for parts and work done and get it mapped properly after its done and that thing will be worth good money down the line if you wanted to sell it :) which you won't lol!



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#30 ·
What I find astounding is the fact that guy has gone through a partial rebuild already (so I guess old oil starvation has been taken off), with forged bearings and a lot of other things, how can it be faulty 6000km later?
Bad work?
 
#36 ·
Update (wow this seems like a long story):
The seller actually contacted the workshop, and the workshop is gonna take the car back in charge and get the job done again (hopefully correctly).
Of course, the seller accepted and now wants to sell it back to me for 50k euros (which was the original price).

I'm not sure I will follow, since we now know the car had problems from a poor work (at the same time, he might eventually get the job done properly this time?)

I would have prefered to get it for 40k and get the rebuild done from a reputable workshop...