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'97 2500 Laramie 4x4 NV4500, 3rd gen rims, BF A/T KO2 285/70R17
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Discussion Starter · #1 ·
My truck is a '97 12v 4wd with a manual NV4500. I bought it before just a year and i noticed that when i pass a chuckhole, a road hump or if i drive off road i cant keep my throttle pedal steady, the truck is starting to jerk/jump, my foot is trying to return it in normal rpms and the whole thing is like a domino unless if i take my foot off the pedal....very annoying because i can't enjoy a nice ride in the countryside. I searched a lot, many people had same or common problem but i am a little bit comfused as my truck is manual and it hasn't a TPS. I checked it and i must put a lot of pressure to start pushing my throttle pedal and it reaches a point and then it becames sticky and stiff again so i must put more pressure to pass this second clicky point and touch the floor. I checked my throttle and cruise control cables and look ok and probably recently changed. I checked the rod and has some play, back/forward and inside/out, the 3 tension springs look unrust and in good condition. The spring in bell crank lever looks also in good condition and unrust, not very smooth but i have no experience before this truck in cummins engines. I don't know about the 2 plastic bushings in it. So as i put my hand to the back of the linkage kit with the engine on to open the throttle i realised that this sticky/hard point caused from the lever throttle (cummins 3931527). I take off the rod and i gave one more turn to the front end to reduce the play and i saw that the plastic bowls inside the frond and rear ends are staring to fail. I saw many videos with guys that ordered specific parts to renew the throttle kit but as i am far from US i think that is better idea to purchase the whole 4089112 kit and change it because i am afraid that maybe i will find more failed parts as i will try to change specific of them. Thoughts and advices please? A i saw the replacement isn't too hard to do it, what do you propose to order, i must order also new cables just if, also the rod comes the ends screwed in the right lenght or i must set them in a specific lenght after ?
 

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Take everything apart and clean it real good. Replace worn parts, bushings and balls& Sockets.

Usually a bouncy throttle is caused by worn out throttle returns springs.

94-96 manuals have 2 return springs 97 + should have 3.
 

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i must put a lot of pressure to start pushing my throttle pedal and it reaches a point and then it becames sticky and stiff again so i must put more pressure to pass this second clicky point and touch the floor.
This is with the engine off? Perfectly normal if the engine isn't running. While you are replacing the rod ends don't forget the throttle bushings. Inspecting and servicing the throttle linkage I'm going to do mine again soon, this time with brass bushings. PDD Brass P7100 Bellcrank Bushing | Power Driven Diesel
 
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'97 2500 Laramie 4x4 NV4500, 3rd gen rims, BF A/T KO2 285/70R17
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37 Posts
Discussion Starter · #4 ·
Hi mates! So as an update....i took everything apart and cleaned it very good. First I changed the bellcrank bushings with the PDD brass bushings and now the bellcrank is moving more freely, nice update. I disconnect the throttle rod and the throttle lever, i checked that the rod ends will need a change with new ones in the near future but for now are still ok and functional. I double checked my throttle cable which was new from the last owner and it moves also freely, i disconnected it and my dad was pushing the pedal from inside the cabin so i am 100% sure that the cable travel is perfect. But i noticed that the sticky/hard point is from the throttle lever on the back of the pump. It appears at the first 1/4-1/5 of the travel and you must put more effort to overpass it with your hand or with your foot on the pedal. As i read a noticable sticky point is normal with the engine off and the solenoid in this position but the thing is that in my pump this sticky point is there with also the engine on, the first 1/4-1/5 of the travel is smooth but it needs a lot of pressure to overpass it and have again a normal throttle till the fully open operation. And when i am between 1500-1800 rpms and in this sticky point and hit a bump or i am offroading where is hard to hold steady pressure the truck is starting to jerk badly and i must let my foot from the pedal. I think that i can't discribe it better....
First i decided to change everything expendable as rod ends, springs etc or to order the whole 4089112 kit from PDP as the recall 05011726AA Kit isn't available anymore but as the sticky point is from the throttle lever travel and not from the bellcrank or the linkage rod i think that i will waste my money. I tried to sortened the linkage travel as my gearbox is manual and isn't necessary to keep the 126.5mm from the bellcrank ball till the bracket but the problem is still there. Had anyone before the same problem to help me, maybe a sticky spring inside the pump or something etc??? A little help guys!!!
 

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‘98 2500 Quad cab 12 valve 4x4 with 5 speed
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512 Posts
Do you know if it has possibly had 3 or 4 GSK springs installed in the pump? I’ve heard the cheaper ones can result in a really touchy throttle
 

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My GSK was touchy when new. Age/miles and bigger tires calmed it down.
 

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'97 2500 Laramie 4x4 NV4500, 3rd gen rims, BF A/T KO2 285/70R17
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37 Posts
Discussion Starter · #7 ·
During the disassembly i tried to move forward and back the bracket where the throttle lever bolts on and i think that its travel wasn't so smooth. I am pretty sure that the sticky point caused from this bracket or something inside the pump that moved from this bracket....i am not so familiar with diesel tech yet so i am sorry for my poοr knowledge. And the thing is that i can't know if one of the last owners from Italy put heavier pump springs. So before i go my truck to a Bosch diesel pump service here in Crete, is something that i can check or do my own to be sure that this hard point in the throttle travel that causing this jumping/surging is from inside the pump and not from the throttle linkage kit? Thanks guys for your help in advance!
 

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I am of the opinion ( no science ) these rear leaf packs all the while riding stiff n crappy like a good 2nd gen should ......... Go Floppy .....
There i said it .
Yes im old . Yes im crazy , but i have witnessed this more than once .

Bring on 4k springs , much fuel , DV's , lord only knows what is done to the AFC control ,, manual trans with Aggressive clutch ................ and you get the bucking/jerking that will NOT stop till you press the clutch in and start over .
I call this phenom " the boot scoot boogie " .
My 94 bomber had it BAD.

Things that help.
Properly adjusted 4k springs
Proper throttle return springs

A Solution :
Traction bars or a new Denver Spring leaf pack.
98% of my very bad " boot scootn boogie " GONE . The truck has somewhat manners now with traction bars . Still rides like crap like a good 2nd gen .
 

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‘98 2500 Quad cab 12 valve 4x4 with 5 speed
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You might read through this. Might be able to glean some info on what you’d need to be looking for inside your pump as to whether or not you have heavier governor springs. I’m assuming you have verified that someone has already been into the pump? This would be evident by the break off screw having been removed and either left out or replace with a different bolt
 

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I am of the opinion ( no science ) these rear leaf packs all the while riding stiff n crappy like a good 2nd gen should ......... Go Floppy .....
There i said it .
Yes im old . Yes im crazy , but i have witnessed this more than once .
My thought is, that along with the rest this is probably a factor, along with possibly the springs in the clutch disc.

Leaf springs start to wrap up with very little torque input, I can notice the difference in my rear springs with which direction the truck is parked on my sloped driveway. The tall riser blocks used in a 4wd would do much to exacerbate the problem, add tall tires, add mushy clutch springs, and it could get pretty bad.

Must be an interesting story about how such a truck got to Crete...
 

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'97 2500 Laramie 4x4 NV4500, 3rd gen rims, BF A/T KO2 285/70R17
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37 Posts
Discussion Starter · #12 ·
I tried to verify if someone of the last owners has already been into the pump and changed the stock springs with 3K or 4K but the wire looks untouched. The only thing that has been changed throught the years is a new solenoid...at least that is the information from the last owner. Maybe something inside the rear side of the pump where the governor/throttle lever bolts is starting to worn out as everything looks stock but i can't believe it as these machines were made to meet the apocalypse or....throught my search i found this in the forum from a guy that his throttle lever was too sensitive at the first mm of its travel and then was meeting a sticky/clicky/hard point that was causing this jerking-bumping activity at low rpms (under 1800). When i don't left my foot from the pedal to eliminate this jerking and i puss more to overpass this point the throttle is getting less sensitive and as stiff as should be for all of its travel. Mister dd453ford wrote as advice this : Could your governor arm possibly be adjusted too low and be going under the fuel stop plate or under the AFC foot? Especially if a previous owner has modified or replaced the fuel plate and/or modified the AFC. And as i suppose that my idle speed is low enough (the same as this idle speed from an auto) without the A/C on maybe that's my problem....thoughts?!
926786
926787
 

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'97 2500 Laramie 4x4 NV4500, 3rd gen rims, BF A/T KO2 285/70R17
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Discussion Starter · #13 ·
or my idle stop bolt is too low and is needing adjustment to overpass this hard point?
 
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