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24th Sep 2019 4:29 pm
knwatkins
Member Since: 19 Sep 2018
Location: Poole, Dorset
Posts: 716
Same as happened on mine pigscovery. Do you have a warranty?Kev
MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey
24th Sep 2019 7:01 pm
dgardel
Member Since: 03 Nov 2009
Location: Greater Venice
Posts: 2025
TV8383 wrote:
As the owner of an SDV6 and a mechanic I have been watching this subject closely over the last year or 2. I have never seen a snapped crank from this engine in the flesh as they are rarely discussed in Australia for what ever reason but have seen and read about several through forums and facebook and google and I have concluded/speculatively
1. The engines are designed on the limit of emissions/reliability.
a. Lower than normal oil pressure
b. Very optimistic recommended oil and filter change intervals (It wan only 10 or so years ago
where if you didn't change the oil in your diesel every 3-5000 you were a monster!!)
c. Undersized harmonic balancer.
d. Light weight internals
2. Some crank failures are unavoidable - when factors line up during manufacturing such as the block is
machined at the end of a run before machine calibrations and the same with the crank and tolerances
are at opposite ends of the spectrum. I think these are the ones we hear about that fail at silly low
mileage and the rarest and don't necessarily fail in the "famous" spot.
3. The ones I have seen/read about that snap at the fillet between number 2 bigend and number 2
main all seem to have poorly bottom end bearings in particular number 1 main. I theorize
that the clearance created by this accelerated bearing wear for what ever reason (harmonics,
lubrication - oil quality/pressure/quantity/extended intervals/dilution allows the front section of the crank to
move laterally within this clearance, independent from the rear section (2nd main back) exacerbated
by the undersized harmonic balancer, to the point of failure.
Personally I change my oil and filter every 4000 miles with an oil analysis for peace of mind and watch my oil pressure gauge like hawk.
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