tool

My truck has developed a high RPM vibration, IE over 2500 rpm or so it starts to really shudder and gets worse as the rpms increase.

I thought it may be due to a broken fan blade but just had the fan and fan clutch replaced and its still there.

Harmonic Balancer?

DMF going bad?

Same vibration driving or in neutral.

Thanks for any help.

rockcrawler304

Sounds like drive-line to me. First check the carrier bearing on the drive shaft. While down there check the weights on the driveshaft to make sure you didn't lose one.

Could be the DM flywheel but those symptoms are usually at idle.

BigIron70

Inspect the index lines (1) on the damper hub (2) and the inertia member (3). If the lines are more than 1.59 mm (1/16 in.) out of alignment, replace the damper.

You could also have a torque converter causing your vibration problem. Remove torque converter bolts and slide torque converter back against transmission. Start engine and check if vibration is gone or no longer present. If gone then replace torque converter.

tool

Definitely not driveline related (as the truck will do it in neutral)

Definitely not torque converter as it is a manual.

I will check out those dampener marks.

Wonder if that's in my Haynes manual?

tool

Just bringing this back to the top and wondering if anybody has any other ideas or advice?

Because I am replacing the transfer case I also ordered a new clutch and Single Mass Flywheel from South Bend. but I have a feeling that is not it.

I haven't had a chance to check out the damper marks, how the heck do you see them with the fan shroud in the way? Do you have to remove the fan and shroud?

Thanks again.

junebug95628

Bottom bolts of the fan shroud need to be removed then the shroud collapses easily and you can find the marks.


Ooops, just saw the date of this post, sorry for resurrecting.

Steve-l

I suspect the clutch. When my truck was new I also had a vibration. I took it apart, made an adapter and spun up the flywheel/clutch assembly on my large lathe. I found the pressure plate was out of balance. I got a new clutch under guarantee and although better, it was still slightly out of balance. I suspect the problem is common, but in fact doesn't really matter if the engine is kept around 2000 RPM,
, which you should be doing anyway for fuel economy and wear and tear.

tool

It was the DMF gone bad. Replaced clutch and all is well.