Vibration. Clutch or engine?

[Petegraintrain]

(11-25-2022 )Petegraintrain Wrote:  

(11-25-2022 )Rawze Wrote:  had someone here one time with a vibration no one could find .. was in the enigne, it would be real bad at about 1400 rpm or so even in neutral.

turns out that it had a slightly bent (not visible by eye) connecting rod because they re-used the old rods during its recent inframe after the engine had hydra-locked previously and no one bothered to check them properly.

the quality of what repair shops do to these engines is complete s$it these days.. so one never knows any more.

this thing also has a vibration at 1400 even in neutral. But if I shut my engine off. Then restart it and rev it up to 1400. It takes about half a minute for the vibration to come back. And that vibration is worse some days than others.. I would think a bent connecting rod would vibrate the whole time it wouldn't take a bit for it to show up

And this was a new crate engine from cummins (not recon) so I would think it wouldn't have a bent rod from factory but anything possible i guess

[windowrattler]

Does the vibration go away with the clutch disengaged would be the question. In just neutral the input shaft would still be spinning.

[Petegraintrain]

(11-25-2022 )windowrattler Wrote:  Does the vibration go away with the clutch disengaged would be the question. In just neutral the input shaft would still be spinning.

Clutch in or out makes no difference

[tree98]

(11-25-2022 )Petegraintrain Wrote:  

(11-25-2022 )windowrattler Wrote:  Does the vibration go away with the clutch disengaged would be the question. In just neutral the input shaft would still be spinning.

Clutch in or out makes no difference

It's not the clutch then.

[Petegraintrain]

(11-25-2022 )tree98 Wrote:  

(11-25-2022 )Petegraintrain Wrote:  

(11-25-2022 )windowrattler Wrote:  Does the vibration go away with the clutch disengaged would be the question. In just neutral the input shaft would still be spinning.

Clutch in or out makes no difference

It's not the clutch then.

Honestly I feel like I'm dealing with 2 vibrations. The one at 1400 rpm when I'm parked I can't feel in the clutch pedal. But the one when driving I feel in the clutch pedal through out all the rpms

[Nilao]

I have a vibration from 1300-1400 on my 871 whether moving or not, clutch in or out. I'm 99% sure I have a leaking injector causing a miss. I also have a fuel line that will seep a bit of fuel at the connector so I could also be sucking minute amounts of air there as well.

[marek4792]

I was gonna suggest this, lot of times the fuel system and IFSM gets overlooked whether it is an timing/metering actuator, pulsation dampers, check valves, etc..

[tree98]

Will it pass a leakdown test?

[Petegraintrain]

(11-25-2022 )tree98 Wrote:  Will it pass a leakdown test?

How is a leakdown test performed? That's something I have not done yet.