linrick1 Posted May 13, 2010 Share Posted May 13, 2010 Hello all, Paving season has begun here in the northeast and I have been running an 86 RD688S triaxle for the past month or so.350, 12 spd, 18 FA,20 pusher, 44 rears on Camelback - she's no showpiece but a good, solid, well maintained old truck. The problem I have been having is that anywhere from say 20mph on up, empty especially but you can feel it loaded sometimes as well, it will start to surge or hop or some damn thing. It happens most noticeably on smooth, flat roads with a light or trailing throttle. I cant tell if its a hop causing it to surge or vice versa. The tires are all good, cant see the bogies jumping around, the steering wheel is smooth, no vibrations, no weird wear patterns. I'll hold the throttle dead nuts stationary and I can feel and hear this surging/hopping. Any input on this vexing issue is appreciated, Thanks, Rick Quote Link to comment https://www.bigmacktrucks.com/topic/13873-hopping-or-govenor-hunting/ Share on other sites More sharing options...
Rob Posted May 13, 2010 Share Posted May 13, 2010 Hello all, Paving season has begun here in the northeast and I have been running an 86 RD688S triaxle for the past month or so.350, 12 spd, 18 FA,20 pusher, 44 rears on Camelback - she's no showpiece but a good, solid, well maintained old truck. The problem I have been having is that anywhere from say 20mph on up, empty especially but you can feel it loaded sometimes as well, it will start to surge or hop or some damn thing. It happens most noticeably on smooth, flat roads with a light or trailing throttle. I cant tell if its a hop causing it to surge or vice versa. The tires are all good, cant see the bogies jumping around, the steering wheel is smooth, no vibrations, no weird wear patterns. I'll hold the throttle dead nuts stationary and I can feel and hear this surging/hopping. Any input on this vexing issue is appreciated, Thanks, RickIf it idles smooth and steady, I'd suggest changing out the throttle arm on the side of the injection pump, and looking for loose connections in the throttle linkage as a start before moving to the governor internals.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/13873-hopping-or-govenor-hunting/#findComment-55017 Share on other sites More sharing options...
GreenGiant2 Posted May 13, 2010 Share Posted May 13, 2010 If it idles smooth and steady, I'd suggest changing out the throttle arm on the side of the injection pump, and looking for loose connections in the throttle linkage as a start before moving to the governor internals.RobSOUNDS THE SAME AS MINE. LOOK BACK A WEEK OR SOIN THE FORUMS AND LOOK UP DM 690 WITH 300L ENGINE HUNTS.GG2 Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/13873-hopping-or-govenor-hunting/#findComment-55021 Share on other sites More sharing options...
linrick1 Posted May 21, 2010 Author Share Posted May 21, 2010 Thanks Rob and GG2-its for sure the govenor. Now all we have to do is scrape up the 2K to get it rebuilt. Thanks, Rick Quote Link to comment https://www.bigmacktrucks.com/topic/13873-hopping-or-govenor-hunting/#findComment-55499 Share on other sites More sharing options...
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