Knocking/ vibrating under load

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Knocking/ vibrating under load

Postby LandTug2 » Sun Aug 09, 2015 11:33 am

This has been posted over on Cumminsfurum as well so sorry if its a repeat for a few people but I just wanted to get a broader opinion if possible:

Hey everybody! I tried reaching out about this a while ago but to no avail... I have a terrible knocking/ vibrating that appears under load starting between 1900 ish rpm and up through 2500 rpm. I have been able to replicate it with the truck stopped and out of gear though it is much fainter and through the same rpm range. Load appears to amplify it. I have had the truck since 2013 and bought it from the original owner who took meticulous records of everything done to it. He was a retired gentlemen who used it to tow his 5th wheel exclusively around the country. It has been happening since I bought it and seems to be harsher at some times more than others. The truck is slightly modified... all in the signature. I read through a lot of similar threads and found this one: 93 knock under load

This sounds dead on to what I have been seeing with the vibration in the pedal and everything. Unfortunately, it didn't seem to nail it to the wall to a symptom. IIRC I messed with the play on the crank and it did move a bit but I didn't have a dial indicator available so not sure where it sits exactly. I also have ATP Super damper on it that I put on during the compounds and didn't make a difference. The old damper was a little worse for wear. The valve lash has been gone through but I still need to check for a bent push rod possibly. I don't think its a U joint as RCCummins was explaining in the thread as I can replicate it at a stand still. So far (knock on wood) it hasn't had any ill effects other than the knock and vibration. I have put 30,000 miles on it myself. The truck pulls hard, idles smoothly, and starts right up every time. It's just really embarrassing and annoying while driving around town as it is really prominent outside the truck. Any body nailed this down?? Really want to fix this thing :grrr:
'93 D250 5x16s, Stg1 pin, 3200 gov spg, stiffer afc spring, pump tuning, Super Harmonic Damper, Timing Spacer, hx35/ht3b compounds, 100 gpm lift pump, 12" Cone filter, Moog Springs, pyro/drive pressure/boost/f. pressure/tach gauges,valet switch, 4'' straight pipe, mag hitec dif cover
LandTug2
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Re: Knocking/ vibrating under load

Postby ellis93 » Sun Aug 09, 2015 12:43 pm

does it change any with the temp of the engine?
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: Knocking/ vibrating under load

Postby LandTug2 » Sun Aug 09, 2015 12:45 pm

I don't believe so. Granted I try not to get in it when the motor is cold but from what I could tell, no.
'93 D250 5x16s, Stg1 pin, 3200 gov spg, stiffer afc spring, pump tuning, Super Harmonic Damper, Timing Spacer, hx35/ht3b compounds, 100 gpm lift pump, 12" Cone filter, Moog Springs, pyro/drive pressure/boost/f. pressure/tach gauges,valet switch, 4'' straight pipe, mag hitec dif cover
LandTug2
fuel screw!!!!
 
Posts: 46
Joined: Sun Dec 21, 2014 12:09 am
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Re: Knocking/ vibrating under load

Postby ellis93 » Sun Aug 09, 2015 4:47 pm

Just once,try it.
There are tsb's out on 24vs rattling hard under load due to low engine temps. Supposedly.....

With your fuel and air.....might be something to look into
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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ellis93
14mm rotor
 
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Re: Knocking/ vibrating under load

Postby LandTug2 » Mon Aug 10, 2015 7:02 am

Wow really? I will have to look up some old tsb's for our generation of trucks. Any idea what might cause it due to cold temps? Gaps in the rocker assembies? I will say it happens when the motor is fully warmed but maybe its the same principle...
'93 D250 5x16s, Stg1 pin, 3200 gov spg, stiffer afc spring, pump tuning, Super Harmonic Damper, Timing Spacer, hx35/ht3b compounds, 100 gpm lift pump, 12" Cone filter, Moog Springs, pyro/drive pressure/boost/f. pressure/tach gauges,valet switch, 4'' straight pipe, mag hitec dif cover
LandTug2
fuel screw!!!!
 
Posts: 46
Joined: Sun Dec 21, 2014 12:09 am
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Re: Knocking/ vibrating under load

Postby ellis93 » Mon Aug 10, 2015 3:35 pm

I can't remember what the explanation was,only it was out there.

I failed to find a noise in a 12v ppump engine recently.....so I might not be much help lol
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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ellis93
14mm rotor
 
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Joined: Wed Feb 17, 2010 3:16 pm
Location: lucedale,mississippi
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