Steve Carey Posted December 3, 2012 Share Posted December 3, 2012 Recently aquired a 76' Mack R600 with the inline 6 diesel. Dont know a whole lot about it but she lopes or surges like a horse. The rpms jump all over the place. I have asked numerous other people about them and they have no answer of what the problem is. Starts and runs fine if you either want to idle or keep your rpms at 2000, anything in between and the tach is jumping 500 rpms. I can hold the accelerator pedal fine but any bumps in the road and it goes to bucking. Even on some smooth roads when I want to hold only 1600 rpms, it just gets to loping again. Shes rough but I only use her for 40 hours a year and they are a long 40 hours with this engine lope. Quote Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/ Share on other sites More sharing options...
jakebrake86 Posted December 3, 2012 Share Posted December 3, 2012 I had an '87 R model that did the same thing. The govenor's wore out. I spent $1400 on a pump rebuild and it ran like a new truck. Quote Jake Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149199 Share on other sites More sharing options...
farmer52 Posted December 3, 2012 Share Posted December 3, 2012 I was thinking Mack offered min-max governors on some applications. Is this correct? Or was the min-max governor only on 2 strokes?FYI, min-max governers only govern at idle and high idle.I remember trying to run part throttle performance on 2 strokes...they were a bitch! Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149217 Share on other sites More sharing options...
39 Baby Mack Posted December 3, 2012 Share Posted December 3, 2012 The first thing i would look at would be the accelerator lever on the governor.It has a self centering spring built into it to eliminate over torquing the shaft in the governor in full fuel position.If the spring is broken in it, which they often do, it will let the governor float and cause it to surge or lope.Ron Quote Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149220 Share on other sites More sharing options...
miro Posted December 3, 2012 Share Posted December 3, 2012 I agree with 39 Baby Mack check the over center spring on the throttle lever Quote Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149227 Share on other sites More sharing options...
Steve Carey Posted December 4, 2012 Author Share Posted December 4, 2012 Hey thanks for the replies, once we get my grandpa's loadstar international out of the shop, i'll get the mack in get brakes ordered and Ill start playing with that throttle. Quote Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149357 Share on other sites More sharing options...
doe70 Posted December 6, 2012 Share Posted December 6, 2012 gday, guessing that might be one of the reasons they sold it, definately sounds like govener is hunting, if pump ok, might not be too dear to fix, and imagine theres a fair few old pump/goveners floating about over there might just swap it out for 40hrs yr.cheers Quote Link to comment https://www.bigmacktrucks.com/topic/28655-76-r600-lope-or-surge/#findComment-149638 Share on other sites More sharing options...
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