On May 29, 2009, at 5:20 PM, tyler wrote:
Is it possible the pistons melted for some reason other than a lean
condition? I can't explain why those four vehicles melted pistons
since I haven't seen them- but I can't imagine it being caused by a
lean condition. Lean = cold, rich = hot EGTs in a diesel. Surely
someone else can back me up on this? I have tuned several modified
diesels with an EGT gauge, and lean equals less smoke, low EGTs, less
power, and rich equals more smoke, high EGTs, more power.
Perhaps those engines were actually running too rich, were being
lugged, or had their injection timing set incorrectly?
Tyler
Tyler,
The common denominator for all of those motors and the respective
cylinders that experienced the heat damage were defective injectors
(melted pistons and cracked/melted rings). The three motors I
personally examined after the fact had injectors on the respective
cylinders with way above spec pop-pressures and poor spray pattern.
These motors were a mix of low and higher mileage, IP timings set to
the T, and driven so that there was not really any carbon on their
valves; driven as a diesel should. Two of those motors suffered their
deaths in less than 10k miles of having injectors installed, the other
after about 20k and did not nail when hot, and just a hint at startup.
The symptoms came on hard and sudden without warning. The other one,
iirc, also had recent injector replacements. Since that fiasco, I never
install any injector without testing it first, regardless of the maker
or the seller.
i understand where you are coming from regarding too rich and high
heat, however, there is also heat that can be caused by a lean
condition that plays hand in hand with detonation. As with most things
in life, there are exceptions to the rules.
Mathieu
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