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The Effects Of Cold Weather

7.3L Injector Sleeve Failure
 
Posted March 1 2012 02:27 PM by Mike McGlothlin 
Filed under: Diesel Engines, Trend Observations, Ford

old sleeves

  In the June issue, you'll read about a somewhat rare problem on 7.3L Power Strokes: injector sleeve failure...


 What we discovered while working on the story was that, while sleeve failure is virtually non-existent in trucks based in mild-to-moderate climates, it becomes more common the farther north you go. Because of this, injector sleeve failure is linked to cold weather. And we mean cold. Different Strokes of Alaska is a Power Stroke shop based in Anchorage, Alaska, that spends much of its time diagnosing and fixing cold weather-related issues. According to them, the problem is caused when an engine's cylinder temperatures go from subzero to 600, 700, 800, even 900 degrees in a matter of a few minutes (thanks to high idle switches for quicker warm up). These repeated, extreme, in-cylinder temperature swings, along with the fact that the brass sleeves and cast-iron heads expand at different rates, takes its toll after a period of time.

 Over the past several years, Different Strokes of Alaska has performed nearly 70 injector sleeve replacements—the majority of them on ’01 to ’02 model 7.3L engines. Its theory behind this is the fact that due to the factory upping the horsepower output of these engines (250 hp with auto transmission, 275 hp with manual), in-cylinder temperatures run slightly warmer. If this is the case, the difference from cold startup temperature to the typical operating temp of the engine may be even greater than in earlier model engines. The fact that very few of its first-generation (’94.5 to ’97) Power Stroke customers have experienced injector sleeve failure supports its theory (early 7.3L's were rated from 210 hp to 225 hp).

 *The only thing we would add to the above theory is that many more ’01 to ’02 engines were built than ’94.5 to ’97 engines, which would explain why more of the later engines experience problems (more engines mean you're bound to see more problems).


Failure Note:

 -The fact that nine times out of 10 the sleeves crack vertically means plenty of expansion occurs in the cylinder, during warmup. The image below represents the type of failure that occurs in just 10 percent of all injector sleeve failures.

Unique failure where the sleeve did not crack vertically. — Photo courtesy of Rosewood Diesel Shop


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