Originally Posted by Edwright105
Ok, I am a marine engineer so I thought I would weigh in... First off I don't really think that running your engine at wide open throttle in neutral is a very good idea.. Diesel engines do not respond very well to this kind of treatment. Diesel engines run best under loaded conditions (rated full load is optimum but not realistic that you will run at that load all the time). Likely the rpm of 3600 that you are reading about is under loaded conditions... if not you could have a slight problem with your governor, a difference of 400 rpm is however not anything you need to worry to much about. As for having bad rings, and blow by I don't think that is very likely because once a diesel starts firing on an external fuel
source ie. lube oil blowing by the piston rings... which is very unlikely, the engine will usually run away and you will have a very big problem on your hands (a catastrophic failure) In any case a difference of 400 rpm's is not a huge deal, don't sweat it
I picture this engine being run at open throttle as only a test, and it was discovered that it was actually able to reach 4000 RPM by using two different tachometers. But just suppose that the tachometer sensor is faulty? Cam was right in suggesting eliminating a possible error with the tachometer setup and using an independant electronic rpm tester. The 3600 RPM is a one hour rated output at the flywheel. The continuous rated output for the 3JH2 is 3400 RPM at the flywheel. If I remember correctly on this particular diesel the adjustment for the high speed setting at the govener is wired off by the factory to proper specs. The low speed idle adjustment was left as end user adjustable. So, if 3400 RPM is the factory continuous rated output, and this engine is purported to be able to run at 4000 RPM wouldn't that make it as 17% above redline condition in continuous operation mode?