Drive chain snapped??

[X5DOB]

Hi

I am seeking some info/help with my 2008 BMW E70 3.0sd.

Driving along last week and it suddenly cut out and came to a half, I have been told that the drive chain has gone (did start sounding like a tractor very quickly) so I do believe this is the problem?

What are my options/costs with scrapping it/re-con engine/new engine???

Thanks for your help!

[X5Sport]

Do you mean the timing chain?  If so, how on earth did that happen?  Any warning sign/noises?

If that's really the case you are unfortunately and realistically looking at a replacement engine as I don't think the BMW engines are 'valve safe' meaning you will very likely have piston, valve and head damage.

I've not seen a BMW engine with that failure, but those I have seen with valve strikes were not repairable.  There are a few reports of M57 engines suffering timing chain failures, usually caused by oil issues, and the reports all suggest the engine will most likely be a write-off due to the cost of identifying the consequential problems that may have been caused in areas such as crankshaft, camshafts, bearings, valves etc.

Don't bother asking BMW for a replacement quote.....it will be frightening!  Even getting it diagnosed by them could well cost you a substantial amount of money at their labour rates!  Try to get an engine from the same type of car as it will have the same sensors etc.  Then use your existing DDE unit to make sure the engine will start and play nice with the rest of your car.

Not the best thing to happen at this time of year.  Any warranty?

Richard

[RenoHuskerDu]

It seems that more and more modern engines are not 'valve safe' as you say. I agree that a new motor is the likely outcome. I had an old Jag break its timing chain on me at idle once, and it still broke 2 pistons and valves, bent others.  BTW, yanks call this an 'interference' engine: http://en.wikipedia.org/wiki/Interference_engine

[X5Sport]

The last 'valve safe' engine I had was an 8-valve 1991 Cavalier. the 16V ones were very 'unsafe' and had rubber cam belts which I absolutely detest.  I don't think diesels have ever been safe due to the compression being that much higher.

Richard

[kkx5]

Most bmw's petrol are valve safe... Even now,  3.0d is not valve safe... And its very common for this engine to have chain issue,  same as x3 n47

[X5Sport]

What causes it?  Not strong enough, oil issues, excessive wear or loads?  Timing chains should not snap,
I mean they are duplex chains from what I've seen, so what's gone wrong?

I knew about the n47 series in various models being 'at risk'.

Richard

[kkx5]

Low quality... Bad tensioner design... But mostly,  low quality.  N47 its a "benchmark"  but m57,m57tu and all the rest are very prone. 

[damian777]

How many miles  had your  2008  X 5 done when the  duplex timing chain snapped ?  Rubber Toothed steel braid  Timing Belts usually carry a  replace recommendation at 50,000 miles  but i would have thought a double linked  Duplex  steel chain would be much higher.  Never herd of X 5 chain breaking  before. 
Scrap yard visit may be cost effective option for a  full engine , but you need to find a  2008 SD variant which are a bit less ubiquitous.Good Luck
D

[RenoHuskerDu]

Just for a reference point, the chain on my W110 560SEL years ago was stretched. The indy garage determined that my checking valve timing. I had it replaced (elaborate, expensive) and the correct timing gave the car a lot more torque. It was a precaution against it breaking.

I wonder if valve timing can be checked on our cars too, to see if the chain is stretched, as a early warning?