trickster5000
Member Since: 12 Dec 2015
Location: East Yorkshire
Posts: 490
 
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XplusYplusZ wrote:Chatting with an LR Assist mechanic today, I asked him about the lengthy service schedules. HE told me that if the DPF cleaning cycles aren't completed, fual used in the cleaning process ends up in the sump, mixing with the engine oil - there's a sensor to check if the dilution percentage hit 5-6%, at which point an engine oil service advisory will come on.
I was really surprised to hear this, but did indeed find similar confirmation elsewhere.
Given that I do a lot of short runs in my vehicle - not ideal to complete full DPF cleaning cycles, it has gotten me a little nervous..
A DPF will passively regenerate above a certain exhaust gas temperature (typically motorway/high speed or load driving) but if it spends too long below that temp, the soot load increases inside the DPF until the engine has to do a forced regen. One of the main ways to increase the exhaust gas temp for this forced regen is to have a large post-injection shot with a lot of fuel ending up going out of the exhaust - it then passes over the DOC which burns it off and hence increases exhaust temp. The problem with such late injection is the unburnt fuel can end up on the cylinder walls, making its way back to the sump and leading to the oil dilution you mentioned. This is also why fuel consumption goes up significantly during a regen.
So a vehicle that is driven long/high speed journeys regularly will do less forced regens and hence less risk of fuel-in-oil than a vehicle that does most of its DPF regen actively. Matt.
'89 90 CSW with a 3.5 V8 conversion (WIP) - http://www.defender2.net/forum/topic46809.html |
8th Apr 2024 9:16pm |
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