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+--- Thread: Cm871 vibrating and tapping like noise at 1250 and up. (/showthread.php?tid=3683)
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Cm871 vibrating and tapping like noise at 1250 and up. - Husky05 - 10-30-2018
Hello all, OK my demandated cm871 vibrates over 1250 rpm in any gear even in neutral, plus neutral with clutch in. Vibrates enough to shake my mirrors. Also when under load it makes tapping like noise that I can really feel it on my floor next to brake pedal. almost seems like it's getting too much compression from probably over fueling. It has no power loss, no smoking, mpg is great about 7.25 mpg. It's quiet under 1250 rpm under load or no load.
It idles so smooth.
It's not tune issue because I have ran a bone stock mandated cal in and still vibrating when I Rev it up in neutral over 1250 rpm.
Some times up hills it'll shudder at 1300 to 1400 just like it would do at 1000 rpm
I have also noticed that it runs alot smoother in warmer weather around 70+ degrees. I did not get enough time to test it more in the warmer climate.
I did cylinder cut out test a week or so ago when my #4 injector started to leak and smoked like a chimney, that's when I ran the cut out test and discovered the bad injector. All other cylinders tested out fine.
All filters are new.
Engine has little over 50k on inframe, it's practically new motor, only thing reused was block, crank, valve cover and all other components on the outside of motor was used again. Fuel pump, air compressor, CAC, and crank dampener are new.
I am not losing any oil or coolant at all.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Rawze - 10-30-2018
Why did it get inframed?. Could be a bent rod from coolant intrusion into cylinder and it hydra-locking at one point?
I know of one guys truck that did that, it got inframed, and it had an annoying vibration at 1300 - 1400 that never went away.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Husky05 - 10-30-2018
Previous owner said excessive oil consumption.
I'll call him tomorrow to see if I can get more information.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Husky05 - 10-31-2018
I am going to get compression test done on Monday to see where it's at.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Husky05 - 11-07-2018
I just got the truck back from the shop, they gave my engine a clean bill of health, said it's very strong engine and do not see anything wrong with internals. They said they do notice vibration when revving it up but it is very small. Said it could be something fuel related.
They did manometer test to check compression, it averaged out 5inHg. so that is good and within specs.
I am not sure where to start now lol I am thinking of getting one timing and metering actuators just only one of each for one bank and install on front then see if there's a difference, then switch to back and see. Also get a new fuel shut off solenoid. I don't have anyone here with spares to borrow.
Fuel pump is already new, not sure about lift pump.
Then after that and problem is still there, I'll try some sensors.
This is going to be a expensive journey. But going to order new motor mounts as these are original and it's time anyways.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Hedley - 11-07-2018
What about your Vibration Damper, was that replaced when you did the in-frame?
RE: Cm871 vibrating and tapping like noise at 1250 and up. - dhirocz - 11-07-2018
Odd, I came here to make a post about the same thing...
I already had mine @m*m^2'd, and it already gotten a new damper, power steering pump and air compressor in the last 80k miles. Had a bearing roll among other things in the last 100k. Sounds like it is coming from the driver's front of the engine but it only happens under torque so I can't replicate it at a stop.
It's enough to make you worry. I wonder if this air compressor is starting to knock...oil pressure is fine, but I also suspect the damper...since it's buzzing a bit between 1200-1400 and I can't get rid of it. Ill also be pulling the front cover to see if I see anything ugly under there.
Oil pressure is fine otherwise and I'm not finding anything externally obvious. To the OP, it sounds like we are having a similar problem, except mine only does it under torque.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - Husky05 - 11-07-2018
Mine is very noticeable under torque, let off it's smooth.
It's a really annoying feeling to have all day long right on my feet, if I lift my feet off the floor with cruise on, its all gone and quiet. A lot less feeling to my feet if I keep it back over side of my seats. Just as long as the boost never goes over 10psi it's all quiet down there. WHen i had my mechanic drive it as I sat in passenger seat, I could not feel it at all. So it's all over on drivers side.
I am getting new motor mounts in tomorrow. Hopefully to see some improvement.
The dampener was replaced when inframe was done. It is OEM cummins dampener i believe.
RE: Cm871 vibrating and tapping like noise at 1250 and up. - stevesparts - 11-08-2018
Also might want to look at the input shaft on the trans, just a thought for a vibration problem .and did you look at the cab mounts also if their bad they can let a lot of shake to the floor..