cumminsdriver635

I think this has been going on for a while, and i kinda think its normal, but i just want to run it by you guys... When i am running my truck hard 3/4 throttle +, it seems that at about 2200rpm's i get a clatter/vibration/knock sound. I held the t-case shifter still, and it seemed to help some, but i could still hear it. If i remember right, dads truck kind of does it too. Im pretty sure it cant be a rod or anything because it only does it under load at around 2200-2500rpm's. If i am in neutral, it revs up pretty smooth, and fine. I have never adjusted the valves, and who knows how long it has been since anyone did it. Could the valves be chattering some, and that is what i am hearing, or what do you guys think. Sometimes i think to much about this stuff, and get myself worried, so i figured i would post . Anyway. If anyone has any help, or if your does it to, any help/info would be appreciated. Truck starts, and runs great other than that.

Eric

JD730

At what speeds are these symtoms happening? 2200 to 2500 in drive/OD?

Could be driveline vibrations, bad u-joints perhaps.
My brothers 96 has something similar to your sound. Haven't looked into it yet on his.

G1625S

The Cummins will, at one point or another, rattle every nut, bolt, washer, and screw loose. I go over my rattle trap every 3k or so with a handful of wrenches looking for offending hardware. Check your tranny and motor mounts, too. When they wear out, all kinds of weird new vibrations will make their way into your cab.
Greg

plow

mine has a similiar noise and i have been looking for it but just can't locate it.I think it is coming from the head area possible exhaust valve or bent push rod. If i walk behind my truck not right up on the tailgate but off away from it aways, i can hear it through the exhaust. But with the windows up in the cab it gets louder with higher rpms. can't hear it as bad in the cab at idle like you can standing behind.

cumminsdriver635

Im starting to think maybe my rattle is just something in the cab?? Cant hear it through the exhaust, and i tried it again the other night, and it wasnt doing it, but it seemed like it was doing it again today,so i dont know?? Just worries me sometimes. I want thins thing to last to 400k.

Eric

JD730

True, I had every nut and bolt (4 of them) holding the power steering pump to the vacum pump disappear on me. It was just kinda hanging there.

cumminsdriver635

Anybody else have any ideas on this? It is still doing it. But if i remember right it wasnt doing it the other day. Seems like after it gets completley warmed up it quits, but i have a hard time telling. Its basically what i would call a knocking sound at about 2100-2200rpm. I dont know. I held the
T-Case shifter again and it seems like it helps as i said before, but I can still hear it some... I just wish i could figure it out Also; it seems like i have kind of a dead spot in my powerband right there. You can see the boost drop off about 4lbs. It has been like this ever since the GSK. Maybe i will try to get the video camera and see if I can get a sound video up for you guys to listen to... Thanks guys.

Eric

mr T

hey Eric,

does it happen during while in gear only? or in park and neutral as well?

then...does it happen in all gears or just locked up in 3rd and 4th?

cumminsdriver635

I remember you saying you had a similar flat spot Mr.T. Mine happens in all gears but i can only feel it in all gears now because of the tighter TC. I used to only be able to feel it in lockup in 3rd, and 4th.

Eric

WSA308

Mine seems to ping excessively under load in the same RPM range. I know it is not something loose, it is definately a ping like in a gasser that is out of time. I'm thinking that maybe it is the timing sensor or possibly under fueling. Changed fuel filter with no change.....Is it possible that it could be a CP3 that is on its way out???

I know that I'm not just being paranoid, there is definately something going on here.

Cumminsdriver, Have you been able to diagnose the problem?

WSA308

Mine died about 15 days ago. Been in the shop since...Six new injectors later and still will not start. I told DC on day two that I thought it was the CP3 but they said it was good...four days ago I was told that they think its the injection pump?????? Any progress on yours Cumminsdriver?

cumminsdriver635

No progress here. For some reason, it doesent do it at all hardly in the warmer weather (55* and up). My buddies 94 he got not too long ago also seems to do the same thing, so I guess it must just kinda be normal. It just sounds kinda bad. Oh well. Ill drive her till she blows i reckon

Eric