Td5 heaps of black smoke

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MTurri

Active Member
Posts
124
Location
Patagonia
A mates Td5 Defender (2006) is making lots of intermittent black smoke.

New fuel pump, new FPR, new injector o-rings & washers. New turbo hoses. Boost pressure as well as other fueling parameters all in good order.

No oil consumption. No significant blow-by. Installed known good injectors then known good ECU, all to no avail. Does it either when cold or warm. Sometimes idles ok, other times smokes right from start up, no clear pattern here. When floored for a while it starts burning clean. Intake manifold and intercooler look clean.

Heavy smoking while idling is usually accompanied by abnormally high cylinder corrections (live cylinder readings jump from +/- 2 to +/- 24) and somewhat rough running (not rough as when running on 4 cylinders, just not smooth). No oil in harness, red plug or ECU. No misfiring whatsoever.

At my wits end... any ideas?

Thinking porous head but may very well be loosing it...
 
Thanks Shifty, though being an intermittent problem ('on-off switch') sort of rules that out wouldn't you think?
Not necessarily. A weak valve spring or a worn valve seat can give the same symptoms depending on what position the valve takes up. The valves do tend to rotate at higher engine speeds so can seal properly at certain points then not at others.

The only real way to be sure is to take the head off and inspect each valve and its springs if a static compression test does not show up any issues. Hydraulic lifters do not make a tapping noise like rockers and tappets do if a valve is not seating fully due to weak springs.
 
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