Dad was an engineer for CAT. One day he took me down to show me around and to take a look at the V12 cyl ship motor he just rebuilt. The cylinders on this thing you could actually physically hide in with the heads off. So there it was all ready to be started for its test run and I got given a pair of earmuffs. Standard operating procedure was "throttle set to max and hit the starter" for testing newly rebuilt engines and it still is. They are run for a couple of hours like that, yes with a load connected of course. In any case I can honestly say that was one of the most terryifing experiences standing next to that pounding piece of machinery the size of a truck, exhausts glowing orange. I was actually shaking when I came out of there a few minutes later, dad just had a smirk on his face.
I have to strongly disagree here, I'm a retired Marine engineer (1st class STCW certificate of competency ie, Chief engineer unlimited) with 20 years at sea and 10 years as a flag state senior marine inspector, and that is NOT an accepted practice whatsoever, even on medium sized engines as described.
To put it very briefly,after a rebuild, on 1 or more cylinders, the engine is prelubed, the jacket water (coolant) and engine entablature brought up to temperature and the engine is rolled over slowly on its turning gear. All is stopped and if everything seems okay the turning gear is withdrawn and the engine rolled over and blown through. If all is still okay the engine is started and idled for a short period of time (5 minutes or so) and then shut down. Lube oil pressure is maintained by the prelube pumps. The engine is allowed to rest for a period and any hot spots (caused by localized friction ie. tight clearances) cool. The engine is then restarted and using a run-in routine (usually manufacturer supplied proceedure) it is subjected to gradually increased speeds for varying periods of time. This allows for the wearing in of all the components in a controlled manner. Failure to do this will cause localized overheating leading to wiped bearings, micro-seizures of sliding surfaces (cylinders pistons etc), etc. In allcases, localized point overheating can cause major damage, if not a full crankcase explosion ( a very, very bad thing indeed).
Often the break in period is punctuated with shut downs and internal inspections.
A break in run can take about 12 hours just to get it to running at rated speed, depending on engine size and type. Even then the engine will be closely monitored and inspected for some time before undergoing heavy loading.
As for the maximum speed setting and overspeed tests, all diesels will undergo these on governor setup and as annual inspections. The engine is brought up to running temperature, then (normally) the speed is raised by moving the fuel rack manually and monitoring the engine speed on an accurate tachometer. This test only lasts for a few seconds and the engine is allowed to return to idle (or shut down for the overspeed) immediately.
I have personally seen poorly informed individuals (yes, even some with P. Eng after their names) try to shorten reccomended factory break in procedures and put an engine on to full load prematurely and have seen the engines fail catastrophically! If you're interested,google diesel crankcase explosions and read about the dangers of "hot spots".
, but I don't like to be leaning over a 3B at anything more than idle - it sounds like theres a dragon in there!
