noticed a strange noise while driving on the highway yesterday...

had the windows down and was passing someone at WOT in 6th... heard a banging/knocking/ticking sound that I thought was coming from the right side, but that might have just been the sound reflecting off the car I was passing...

this is not "lug rattle" like when you get into it at really low RPM and you get rattling from the diesel spikes... this is a slower tat tat tat kinda like when a gas motor is rattling from pre-detonation

was able to replicate the sound a few more times... thought maybe exhaust was hitting/banging under the truck? 5" downpipe is kinda tight

pulled over, didn't see anything odd... I had been playing with the wastegate arm earlier in the day thought maybe the wastegate lever was chattering open and closed? or maybe the pop-off valves were bouncing open/shut?

so then I tried to replicate it again with the windows up and it really sounded like it was coming from the tranny area... hmm...

I also noticed that the noise was occuring when I railed on it from 1900 or so and it would rattle around 2000-2100ish and up... and then it would go away...

if I hit it at 2500rpm, it wouldn't do it...

and if I had it happening in the low 2k RPM zone and backed off the throttle a hair, it would go away.

so now I'm thinking it's clutch/driveline related and that it's a torque issue... higher RPM = less torque, no noise... if I'm not at WOT, no noise... less torque...

I'm planning on putting a dual disk in the truck. it currently has an OFE in it... the clutch isn't slipping... wondering if I'm bottoming out the springs in the hub and they're "bouncing" or something?

DDP4's, rips twins w/ a PDR35-12 on top, rack cap is the fuel stop on the 215 pump

already left a message w/ Peter

your thoughts?

 

Forrest, I know it may sound odd but its possible that its a exhaust leak.
I had a similar noise on my 24v that took months to find and I was convinced it was a hard part failure. It sounded like a bad hydraulic lifter in a V8 but would only make the noise at a certain RPM with full boost (load). Turned out it was only a loose manifold flange on #6. No way would I believe it was a exhaust leak that could make that sound? Mike Holman was convinced he had a rod bearing go that turned out to be a exhaust leak also so the sounds can be very deceiving. I'm not saying that's your problem but it sounds suspiciously like what I encountered, seems RPM and load specific is the key so I would say spend some time looking for a exhaust leak. Just my $.02

 

well, the fact that it sounds like it's on the right side led me to look for exhaust leaks, but I didn't find any...

there's the slightest pin-hole leak on the wastegate tube, but it's been there the whole time, and it seems odd that it would make noise only between 2100 and 2400 at WOT in OD and not from 2500+