Help, car at garage, should i replace crank? n47, timing chain

monkins · 07-01-2013, 01:06 PM

Hi,

I have the car at a garage having the timing chain done, looking at the engine while its apart all the chains etc there looks like no wear really. But it was making a shh shh shh loud noise at 1500-2000 revs. The adjuster goes back in about 8mm when compressed.

its a 2007 320d coupe and has done 56k miles, originally I was just quoted a price for just the chains and sprockets and guides, but bmw have informed the garage that the crank should be replaced.

this will add another £1k to the price, I felt the sprockets and i can't really feel any sharp edges or see any where on the whole chain system, but something's causing the noise.

Anyone got away with changing everything but the crank? can the sharp edges be knocked off the sprocket with a file then the new parts will wear fine?

any answer would be appreciated I need to make a decision soon.

My thought is that this noise will come back again even if they change the crank, and it will easily see another 80k miles. Its a lot of money on top of a big bill, I also looked at the new guides and they only appear to be a bit darker plastic colour, and no physical difference. are the chains and sprockets better?

cheers

Chris

IanS100 · 07-01-2013, 08:23 PM

This is a problem recently highlighted on Watchdog & discussed at length on the forum, do a quick search for "Watchdog"

The problem with the n47 engine is the iffy timing chain & that it's a right pig to fix. The chain is located at the back of the engine & changing involves removing the engine, as you've probably learned, and to repair it properly the crank pulley should also be changed, but that's welded onto the crank so a new crank also needed

monkins · 07-02-2013, 02:15 AM

Cheers, I've googled the problem to death and I wanted a concrete reason why to change the crank.

Would seem that the cranks before 2009 on the 177bhp engine have the incorrect machined lobes on the sprocket. So thats the whole cause of the chain pickup noise. So just replacing the chain and top sprocket will not solve the problem.

There was one guy on a forum saying dont let them change the crank but he gave no reason why. Everyone seemed to say the lobes get sharp on the sprocket causing it.

325sport · 07-03-2013, 03:09 PM

Hi I had mine done by BMW outside warranty, as a goodwill they paid for 50% of parts. Cost me 2700 all in with a two year warranty on the repair. Problem appears to be a design issue by bmw that they will nt accept full responsibility for, suggest you get crank done, worth a call to bmw though

IanS100 · 07-03-2013, 04:08 PM

Do BMW ever accept responsibility for their cock-ups?

07-01-2013, 01:06 PM	#1
monkins New Member 4 Rep 25 Posts Drives: bmw 320d e92 2007 Join Date: May 2013 Location: United Kingdom iTrader: (0)	Help, car at garage, should i replace crank? n47, timing chain Hi, I have the car at a garage having the timing chain done, looking at the engine while its apart all the chains etc there looks like no wear really. But it was making a shh shh shh loud noise at 1500-2000 revs. The adjuster goes back in about 8mm when compressed. its a 2007 320d coupe and has done 56k miles, originally I was just quoted a price for just the chains and sprockets and guides, but bmw have informed the garage that the crank should be replaced. this will add another £1k to the price, I felt the sprockets and i can't really feel any sharp edges or see any where on the whole chain system, but something's causing the noise. Anyone got away with changing everything but the crank? can the sharp edges be knocked off the sprocket with a file then the new parts will wear fine? any answer would be appreciated I need to make a decision soon. My thought is that this noise will come back again even if they change the crank, and it will easily see another 80k miles. Its a lot of money on top of a big bill, I also looked at the new guides and they only appear to be a bit darker plastic colour, and no physical difference. are the chains and sprockets better? cheers Chris
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07-01-2013, 08:23 PM	#2
IanS100 Major General 135 Rep 5,050 Posts Drives: 520d F10 LCI M Sport Join Date: Nov 2011 Location: Southport UK iTrader: (0)	This is a problem recently highlighted on Watchdog & discussed at length on the forum, do a quick search for "Watchdog" The problem with the n47 engine is the iffy timing chain & that it's a right pig to fix. The chain is located at the back of the engine & changing involves removing the engine, as you've probably learned, and to repair it properly the crank pulley should also be changed, but that's welded onto the crank so a new crank also needed
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07-02-2013, 02:15 AM	#3
monkins New Member 4 Rep 25 Posts Drives: bmw 320d e92 2007 Join Date: May 2013 Location: United Kingdom iTrader: (0)	Cheers, I've googled the problem to death and I wanted a concrete reason why to change the crank. Would seem that the cranks before 2009 on the 177bhp engine have the incorrect machined lobes on the sprocket. So thats the whole cause of the chain pickup noise. So just replacing the chain and top sprocket will not solve the problem. There was one guy on a forum saying dont let them change the crank but he gave no reason why. Everyone seemed to say the lobes get sharp on the sprocket causing it.
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07-03-2013, 03:09 PM	#4
325sport New Member 2 Rep 25 Posts Drives: BMW 320d Msport coupe Join Date: Jul 2011 Location: Glasgow iTrader: (0) Garage List 2000 Porsche 996 turbo [0.00] 2007 BMW 320d Msport [0.00]	Hi I had mine done by BMW outside warranty, as a goodwill they paid for 50% of parts. Cost me 2700 all in with a two year warranty on the repair. Problem appears to be a design issue by bmw that they will nt accept full responsibility for, suggest you get crank done, worth a call to bmw though
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07-03-2013, 04:08 PM	#5
IanS100 Major General 135 Rep 5,050 Posts Drives: 520d F10 LCI M Sport Join Date: Nov 2011 Location: Southport UK iTrader: (0)	Do BMW ever accept responsibility for their cock-ups?
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