Which is the most robust variant of diesel engine?

[H4MP]

Would it the the single turbo M57 or the twin turbo Sd/35d or the later N57 single turbo or 40d variants. Discuss please

[X5Sport]

The M57 is ‘old tech’ and also more expensive to tax than the later N57. The later engine is also more powerful, economical and cleaner (EURO 4 or 5, my MY2011 X6 is EU 5). I think the turbo response on the N57/40d is better too as the turbos are a different size so you have a smaller low pressure (from idle) and larger high pressure (a bit further up the rev range) that reduce turbo lag. This system has continued on into the current B57 series as well. You also get the superb ZF 8-speed auto gearbox and later iDrive with the 40d, and I think the ZF-8 appeared slightly later (MY2011 onwards) also in the 30d too.

The only downside with the N57 might be if you get trouble with the timing gear (far far less likely than the N47 2.0litre unit) then it’s an engine out job as the timing gear is all at the back. Frequent oil changes will mitigate that risk to a large extent. Timing chain failures are very rare in any of the 6-cyl engine series, but leaving the oil too long has been suggested as a risk in the N57 series. The N47 4-pot has a very poor reputation in all variants.

[H4MP]

That's really informative, it seems the 6 cyl diesel engines BMW has produced are its best creations. When I asked an indie once, he was talking about the M57, he said its one it the few engines produced that does not have any common faults. I don't mean the ancillaries.

[X5Sport]

We still have a 16 year old E46 with an M57 (70k miles only) and it’s never missed a beat. It’s had a new starter motor due to the common issue with cars from 2004/5 and two new brake pressure valves, but at that age they were wear and tear. Similarly our now 11 year old E71 with the N57T has only had new glowplugs & controller (less than 60k on it now), and again those are wear & tear. Both are now given annual oil changes regardless of mileage. Our E53 engine was fine, unlike the gearbox!

Having had BMW 4 and 6 cyl engines we love the IL6 and so have ordered the same in our (much delayed) M340D Touring with the B57 twin turbo to replace our leased B47 20d twin turbo 2er Gran Tourer. Over the generations the engines we have will go from 204bhp PS to 340bhp PS.

[Leslie]

Hi x5 sport its the x5 35d /sd has a big and small turbo I always though the 40d had 2 same sized ones.
There was a sd on autotrader with 350k on it so they certainly can last if looked after, the later engines have the timing chain at the back and this doesn't seem to be quite so durable and seem a few issues posted about high pressure pps on the 40d at high miles.

[X5Sport]

40d is definitely disimilar sized turbos. I had to go look at RealOEM to see a picture as I thought the 35d was the symmetric and 40d brought asymmetric turbos. Every day’s a school day it seems. Perhaps the difference is the 40d introduced VNT to reduce turbo lag? The latest ones have that plus 48V mild hybrid tech to reduce lag even further.

[Leslie]

Perhaps the difference is the 40d introduced VNT to reduce turbo lag?

Yes that's probably it and would explain the more flexible engine hard to remember everything !

[StuBeeDoo]

Daft question..........

Wasn't the 35d M57 and the 40d N57??

[Alan Gunn]

The m57 in my e53 has around 180k on it now and still sweet.
I change the oil/filter every 12 months or 7k but not done anything near the 7k the last 2 years but still did the oil/filter i think last year was less than 1k but still did it.

[X5Sport]

Daft question..........

Wasn't the 35d M57 and the 40d N57??

Correct. The face lifted (LCI) E70 was the point of changeover (with new model des) with the X6 also getting the changeover later in 2010.………and not a daft question