200d rmps surging

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friend here has a 200d that the rpms are surging up and down several hundred rpms,,bad enough yesterday we had to take it off the line..same thing today,welds good for a while then starts again..been back to lincoln 3 times now for repair for the same thing..and starting again..could use some help..thanks
Reply:just ask him what oil he was using, he was using rotella 10-40 instead of 10-30,
Reply:Main problem with most of the 200d's is the position of the brush carriers, Some were fine others were way off like 3/8 +away from the commutator, should be around 1/16 to 1/8" away from the commutator. The problem machines took out brushes and easy to  notice as the commutators were severly black. Often the brushes would break away bending the hech out of the carriers. This blackening would cause the engine to fluctuate  as the load increased and the weld would also become erratic.Unfortuneatly though reported, most techs didn't notice this carrier distance and merely put a new set of brushes in, only for the problem to reappear.Last edited by Cruizer; 10-19-2010 at 01:08 PM.
Reply:Good point Cruizer.  I think I know of at least 7 that are like that (mine and 6 of my present contractor machines).  I say this because you can't keep the brushes seated in them, and they do burn the armature.  My issued 200d at work (a 2008 model) is 'burned up' I know.   I'm a short arc welder and I really work a machine and its showing that fact on it's commutator.If I'm welding hard the commutator turns blue/black and the generator housing will get so hot it'll almost burn your hand especially those seam(?) welds that goes across it on each side.  Needless to say - its welds like a piece of crap when it gets hot and you can easily loose 20 points in 3 rods after a 15 minute break most every day.  I'm definitely at my wits ends with it.   IMO it can't be fixed now. lol A good friend of mine on this job also has a 2003 (only 7 numbers apart from my old machine) and his welds fine and always has with original brushes and 4700 hours so I'm betting his is setup right.But I don't think this would cause the engine to surge in 100 RPM lumps.  If its a Perkins then IMO this must be fuel related, like a filter, water, etc.  If its a Kutoba then with its electronic controls then IMO it could be in that system.  Maybe something loose in there?  Electronics are something else and usually requires meters being put on them to figure them out.  The old Perkins were just a plain old diesel engine and high-idle stop bolt.  A surge in them is probable a fuel delivery problem.   The Kubota's and their electronics IMO is going to mean a visit to someone that knows how to check it out right. lolThanks for the info man. Good luck guysLast edited by slowhand; 10-19-2010 at 06:53 PM.