Odd shake at idle

99_SilvrCummins

99_SilvrCummins

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Feb 5, 2009
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202
Long story here but I'm hoping someone has ran into this before.

Background on truck: 99 2500 ecsb, 4x4 5 speed. Edge drag comp, smarty, fass150hd, 100 hp ddp injectors, tunnel ram, steed speed t3 with an ED billet 63/68/.8ar. Southbend 3600 clutch and hydros and isspro gauges. 4inch exhaust and 5inch air filter. 245k miles now I have owned it since 176k.

Problem: One morning in December I went to leave for work, when I started the truck it seemed to be running rough, as in more shake to the idle than normal. I chalked it up to being cold that morning because fuel psi is 16-17 and drove into work. Did the same after work too. I got home and tried to figure out what was wrong. Idle stays smooth in the 750-800 range so the tachometer is not matching the shake. Check all accessories on the front of the engine for slop, nothing. I even removed the serpentine belt and started it, still shakes. Removed the damper, still shakes.

At this point I pull injectors and sent them to ddp to test them. Ddp found nothing out of the ordinary other than the brass washers on a couple looked like they were passing compression. Thought I had it here, but when I reinstalled them it still shakes.

Drained all my fuel on the off chance I got bad fuel, new filters on the fass, fresh fuel and it still shakes.

This whole time the truck does not white smoke, no codes, no rough start, no dead pedal runs great other than a shake at idle. If I am sitting still and free Rev the motor the shake seems to smooth a little bit but I can still feel it. Driving down the road in gear I don't feel the shake, even at low rpm.

I'm at a loss on what's next. I bought a compression tester so I can pull the injectors back out and test each cylinder but it runs good with no smoke.

Only other thing I can think of is something in the clutch is loose but it has not lost any holding power from what I can tell.

Any suggestions compd crew?
 
badbowtie said:
If you push the clutch in does it change the shake?
Click to expand...

It seems like as I'm applying the clutch in first or Rev it calms down a bit but I can't tell for sure. Wondering if a part of that clutch could come "loose" and not lose holding power or come completely apart.

I'm unplugging the comp and flashing it back to stock to eliminate the programmers from the mix.
 
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badbowtie said:
You could be losing the input shaft support bearing
Click to expand...

This ^. Had the same issue on a stock truck. Would shake and annoy the hell out of you. Finally pulled the trans and found nothing left of the input bearing but the metal lining on the outside... Threw in a new clutch and bearing and its smooth as glass again...
 
Removing the harmonic balancer wouldnt stop a vibration otherwise there would be no reason for the harmonic balancer. Sounds like either the balancer or the clutch. But if it is the clutch then you "should" be able to isolate the problem by pressing the clutch pedal in and out in neutral and also in and out of gear.
 
Check engine mounts????? I just went through something similar to my friends truck. Had 2 broken bolts on the passenger side and the 3rd was MIA. Extracted the two broken bolts out by welding nuts onto what was left of the bolt and backed them out carefully. 3 new bolts and she idles nice and smooth.
 
Katoom said:
Removing the harmonic balancer wouldnt stop a vibration otherwise there would be no reason for the harmonic balancer. Sounds like either the balancer or the clutch. But if it is the clutch then you "should" be able to isolate the problem by pressing the clutch pedal in and out in neutral and also in and out of gear.
Click to expand...

I removed my old one and put a good one on it and it did not stop the vibration.

Tearing the clutch out when work let's up. Depressing the pedal makes the vibration less but it's still there.
 
cetaneaddict said:
Check engine mounts????? I just went through something similar to my friends truck. Had 2 broken bolts on the passenger side and the 3rd was MIA. Extracted the two broken bolts out by welding nuts onto what was left of the bolt and backed them out carefully. 3 new bolts and she idles nice and smooth.
Click to expand...

I will check my bolts before removing the clutch, I checked the urethane mounts themselves but didn't think to check the bolts.
 
Update

I had called and talked to a tech at south bend about this. He mentioned it was loosing the dampening system because it is a street dual disc.

Got it out finally last night and he was spot on. It lost the urethane dampening system, causing the spring steel alignment pieces to break. This all allowed the floater plate between discs to "float" way too much. Throwing the clutch out of balance and causing the vibration.

Putting in a new dd and back to smooth operation hopefully. Maybe this thread will help someone else in keeping them from pulling thier hair out. Thanks to all that responded.
 
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