top overhaul

top overhaul

The overhaul of cylinders, valves, and pistons of a reciprocating engine. The crankcase, in this case, is not opened, and the connecting rods are not removed from the crankshaft.
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"The overhauled Continental had valve problems at roughly 700 hours and four cylinders lost compression, so Powermaster in Tulsa, Oklahoma, did a top overhaul under warranty.
A top overhaul is basically what it sounds like: Remove and overhaul or replace the "top end" of the engine: cylinders, pistons and valves.
Consequently, compared to the conventional system, the minimum oil change interval and other basic maintenance work have been extended to 1.5 times, and the minimum interval for top overhaul has been extended to 1.9 times, reducing overall maintenance costs by approximately 30 percent.
The tops and insides of pistons that were changed during a 20,000-hour top overhaul showed only a lightly baked-on white caking of silicate.
Worse is that the top overhaul, replacement of all cylinders, is almost never necessary--a sick cylinder is not infectious--yet it is still done with alarming frequency.
Usually your writers cover most aspects of various options or points in your articles but in the "Top Overhaul Shops" in the March 2010 issue, it's obvious that Jeff Van West does not fly an airplane for business purposes.
Many owners who weren't flying lots--say, 250 or more hours a year--were going through at least one top overhaul on their way to TBO.
I did a top overhaul last year as my almost 1000-hour cylinders were using too much oil.
Most engines probably make it to their TBO with little more than oil changes and some spark plugs, or maybe a top overhaul, But a few engines roll over long before that.