Join Date: Feb 2002
Feedback Score: 0 reviews
Re: Injectors - how many miles ?
Injector life depends on two main factors. Fuel quality and oil quality.
One bad tank of fuel, contaminated with water, or gas, for instance can (and will, usually) wipe out an entire set of injectors. Not the entire injector of, ourse, but the "heart" of the injector, which is the plunger and barrel assembly.
The fitment between these tow parts (think fitment of piston to cylinder wall) is on the order of 20-30 millionths of an inch.
ANy loss of lubrication will gall these parts in an instant...rendering them useless. Loss of lubrication can also occur when fuel pump goes out, but usually the siphoning action of these parts will actually pull fuel, through the feed lines, and the truck will still run.
That's why clean, well filtered fuel is esential to happy injectors.
On the oil side of the injector, the main wear area is the poppet valve.
This valve opens and closes (similar to a valve in a cyl head) metering the oil into and out of the injector.
With crappy oil, the poppet valve (& seat) will wear much more quickly than with "good" oil.
But at some point, after millions of injection events, the valve and its seat will wear (just from the shear repetitive beating of closing the valve over and over)
When the poppet seat wears, some internal tolerances get all jacked up within the injector...requiring machining to get them back into spec.
If you kept good quality, well filtered fuel in the truck (no water, no gas, etc) then the poppet will usually start showing its wear after 175,000-225,000 miles...
We've seen sets come in with 400,000 miles that had wear, but were still functioning...albeit a little out of balance.
We've also seen sets come in with less than a 100,000 on them that were totally jacked from crappy oil...
As an average life expectancy, I'd say after about 200,000 miles you might need them looked at, and brought back into spec...
Typical poppet valve issues are that a truck runs good cold, but rough when warm...thicker oil can bridge the gap of a poorly sealing poppet than when the oil thins out when hot.
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