CAT 3126 with a nasty GROWL

[Native]

Originally Posted by PatrickBaptist

" I felt the U-joints along the driveshaft."
Did you check for any play though???

Yes, I did. No lateral movement at all. The drive shaft will move a bit in the direction of rotation (clockwise and counter-clockwise). This tells me there is some play in the gears. This is with the transmission in neutral and theparking brake applied. I did the "feel" test while on the road, so I did not get under fully and ynk it around... just from squatting under and leaning in

[Native]

Originally Posted by EastCoastCB

Whatever's going on in Native's bus is engine related in some way.

Sam- can you make a one minute video and put it on YouTube?
You guys have to experience this to fully appreciate it. Its WILD.

I have a 2 minute video uploading right now. It is 2% loaded and YouTube says it will take 2 more hours. So, with any luck the video will be available for downloading sometine tomorrow (Tuesday the 17th).


Note: The cell phone does not pick up the strong resonance/reverberation that you FEEL when inside the bus. I can hear a little of what I call the engine component tapping away at 1800 RPM. So it is not much to get hopes up for.

[Native]

Here is the video.The cell phone microphone does not pick up the deep resonance one feels inside The Beast. I can hear the rhythmic mechanical noise when in the GROWL zone, but I know it well. I hope others can hear it and help out.


Perhaps ECCB can comment as to the weak audio recording.

https://www.youtube.com/watch?v=Fw338R-sXuE

[EastCoastCB]

I can hear it but in person its immeasurably more powerful. The frequency is so low that's probably why that mic isn't capturing all of its glory.

[WIbluebird]

Originally Posted by Native

Here is the video.The cell phone microphone does not pick up the deep resonance one feels inside The Beast. I can hear the rhythmic mechanical noise when in the GROWL zone, but I know it well. I hope others can hear it and help out.


Perhaps ECCB can comment as to the weak audio recording.

Is that the Bluefire gauge app on that tablet? I'm thinking about trying that with my bus especially since my odometer is out (does it read odometer?)

[cadillackid]

I could hear the gear whine of either the rear end gears or if you have aggressive drive tires it might be those..



what I heaer a little of is the sound of an engine being lugged.. you are nailed at 100% Load and throttle it looks like... forever to shift into 4th? or 5th.. that last shift looked like the wide ratio from 1:1 to 0.75:1 on an allison 2000 / 3060..



to me its normal for a diesel at 100% load to sound labored all the down in the 'teens' for RPMs.. esp a HEUI engine.. but you are saying it never did this before?


-Christopher

[EastCoastCB]

Originally Posted by cadillackid

I could hear the gear whine of either the rear end gears or if you have aggressive drive tires it might be those..



what I heaer a little of is the sound of an engine being lugged.. you are nailed at 100% Load and throttle it looks like... forever to shift into 4th? or 5th.. that last shift looked like the wide ratio from 1:1 to 0.75:1 on an allison 2000 / 3060..



to me its normal for a diesel at 100% load to sound labored all the down in the 'teens' for RPMs.. esp a HEUI engine.. but you are saying it never did this before?


-Christopher

Not lugging- it does it only in certain rpm's at 90%+ load. IIRC around 2000-2200 rpm's.
The tires are brand new and were balanced and it even got a pro alignment all from a really good shop.

I do have a new bit of previously forgotten info to add, though.
His bus may have possibly been monkeyed with before. It revs to 2600 and from what I understand 3126's are usually set with a 2400 rpm redline. At least it looked to me like it was hitting up to 2600 rpm when I watched in his bus.

[cadillackid]

if you srtomp one to the floor in neutral it runs up to 2600-2700 and then limiter seems to hold it at 2500 or so.. at least on an HDX.. not sure aboutthe OP's bus.. the run up to 2600 could be a flared shift... under sustained load they arent supposed to be cruised above 2400... even the books say it can hit 2800 under Wide-Open-Throttle conditions



the whine of the tires is more pronounced when they are new if the tread is aggressive.. its normal.. not a bad thing..



foot to the floor and 100% in the low-mid teens is definitely border-line lugging the engine.. it wont hurt it because the RPMs are steadily increasing so the turbo will spool and bring the EGTs down and oil pressure will go up..

-Christopher

[Mountain Gnome]

my 2¢:
every deep-resonant tone I've heard that relate to vehicle speeds have been wheel bearings, except for a set of worn-out low-profile tires on a "sports car". The U-joints have been a slightly higher tone; however, I second the notion that if the U-joints were just worked on, I'd check them first. Maybe they were nicked/scratched when installed, and they won't be loose/wiggling yet.

[EastCoastCB]

Originally Posted by cadillackid

if you srtomp one to the floor in neutral it runs up to 2600-2700 and then limiter seems to hold it at 2500 or so.. at least on an HDX.. not sure aboutthe OP's bus.. the run up to 2600 could be a flared shift... under sustained load they arent supposed to be cruised above 2400... even the books say it can hit 2800 under Wide-Open-Throttle conditions



the whine of the tires is more pronounced when they are new if the tread is aggressive.. its normal.. not a bad thing..



foot to the floor and 100% in the low-mid teens is definitely border-line lugging the engine.. it wont hurt it because the RPMs are steadily increasing so the turbo will spool and bring the EGTs down and oil pressure will go up..

-Christopher

His new tires are all position with very highway oriented tread.

[EastCoastCB]

IDk, but yall are gonna have to ride in this bus to appreciate what's going on with this frequency/boom/resonance. Its bone chilling.

[Mountain Gnome]

Originally Posted by EastCoastCB

IDk, but yall are gonna have to ride in this bus to appreciate what's going on with this frequency/boom/resonance. Its bone chilling.

That's the problem with diagnosing a vehicle remotely.


If it ain't the tires, then it's a bearing (including the needle bearings in a U-joint). You must isolate the sound. They make microphone systems that you can install at various points under your vehicle, in the wheel well, etc, but the problems then becomes that most mics don't pick up sound below approx 60Htz very well combined with the fact that low-frequency vibrations dissipate in every direction, and it's hard to find the source sometimes.


Since it it speed and torque related, it is in the rear of the drivetrain - from the tranny's output shaft bearings, u-joints, pinion bearings to the wheel bearings.


Can you jack up the rear end and put it in drive and crawl under it and have it revved up in drive? If so, then what happens?

[Ronnie]

Originally Posted by EastCoastCB

IDk, but yall are gonna have to ride in this bus to appreciate what's going on with this frequency/boom/resonance. Its bone chilling.

Is he coming to the swarm in February? If so I will be there and would look at.

[Jolly Roger bus 223]

i have heard that before and its usually a rear end noise,
most likely the universal joint being wore out messed up the pinion bearing going into the rear end and now that the the driveline is tightened up then it is showing the true restraint on the driveline or did the drive line cause the pinion bearing problem?
just my opinion
what rearend would help us know if the differential could be pulled toward the driveshaft or if the whole center section has to be dropped? either way the axles have to be out a little and more on others.
more info on your rear end if the phasing of your drive shaft is correct?
is your tranny output shaft leaking now?
is your rear end front seal leaking now ?
were either leaking before?

[Native]

Originally Posted by WIbluebird

Is that the Bluefire gauge app on that tablet? I'm thinking about trying that with my bus especially since my odometer is out (does it read odometer?)

Yes and yes. This is the BlueFire app. It works well enough to be very useful. It does read the odometer, which is ONE of the reasons I purchased it. The odometer is in the upper left of the screen and the trip miles are in the upper right.

[Native]

Originally Posted by cadillackid

I could hear the gear whine of either the rear end gears or if you have aggressive drive tires it might be those..

The video was just after the trip to Florida, after the cargo was removed, thus empty. We were on the way to get new tires. In the video, the bus has Goodyear M+S on the rears. They make quite a howl. There is also a bit of a differential howl which you were picking up on as well.

Originally Posted by cadillackid

what I heaer a little of is the sound of an engine being lugged.. you are nailed at 100% Load and throttle it looks like... forever to shift into 4th? or 5th.. that last shift looked like the wide ratio from 1:1 to 0.75:1 on an allison 2000 / 3060..

Yes, that's what I was thinking. That very mechanical and periodic tick-clank during the 1800 RPM to 2150 RPM range. It seemed to fit the description you gave earlier when you described lugging. The guages support it as well.

Originally Posted by cadillackid

to me its normal for a diesel at 100% load to sound labored all the down in the 'teens' for RPMs.. esp a HEUI engine.. but you are saying it never did this before?
-Christopher

We only REALLY noticed it after loading it up and heading to Florida. Thinking back, it did do it a couple of times while running on the highway as part of flushing the radiator. Those times it was on an uphill climb and very short-lived. So, I would say it increased over the trip.


We replaced the 10R22.5 M+S and steers with 6 Roadmaster all position 11R22.5 RSA's. The ride is smoother, quieter, and the speedometer now reads spot-on. The top-end is now 73 MPH to 74 MPH at about 2500 RPM, though I only occationally exceed 2400 RPM (71 MPH) to pass or make clearance as needed.


The vehicle is now loaded up once again. I will endeavor to make another video in the next couple of days to show how it NOW sounds with the new tires. I will also try to get a better sound recording, if I can.

[Native]

Originally Posted by Brad_SwiftFur

As for the lack of pep, when was the fuel filter last changed? On a diesel with low power issues, that is my *Absolute* first question and the most common cause.

Once we got close to our Florida storage location, it started to send intermittent "water in fuel" sensor light on the dashboard. They came in and out, usually due to a bump. I replaced the fuel filters when the new tires were put on. No change in power.

[Native]

Originally Posted by EastCoastCB

His new tires are all position with very highway oriented tread.

True, but the video was prior to replacing the tires.


I need to make another with the new tires and the new load in the back.

[Native]

Originally Posted by Mountain Gnome

That's the problem with diagnosing a vehicle remotely.

You sure got that right!

Originally Posted by Mountain Gnome

If it ain't the tires, then it's a bearing (including the needle bearings in a U-joint). You must isolate the sound. They make microphone systems that you can install at various points under your vehicle, in the wheel well, etc, but the problems then becomes that most mics don't pick up sound below approx 60Htz very well combined with the fact that low-frequency vibrations dissipate in every direction, and it's hard to find the source sometimes.

I had that same thought earlier today. Placing microphones all along the drive train would help diagnosing this problem.

Originally Posted by Mountain Gnome

Since it it speed and torque related, it is in the rear of the drivetrain - from the tranny's output shaft bearings, u-joints, pinion bearings to the wheel bearings.

It is not really speed related. In 4th, I can hear it a little when the engine speed is 1800 RPM to 215 RPM. Once I get past that and I can get up to 55 MPH with no GROWL ... albeit at 2500 RPM. As soon as it shifts into 5th (overdrive) the RPMs drop down to 1800 RPM and the GROWL starts and continues until about 2150 RPM (60 MPH). This is why I think there are two components to the noise. One is related to vehicle speed and the other is related to engine load.

Originally Posted by Mountain Gnome

Can you jack up the rear end and put it in drive and crawl under it and have it revved up in drive? If so, then what happens?

While I do have a set of 20-ton jack stands and a 20-ton jack, I am not quite ready to jack it up and have the rear wheels spinning.

[Native]

Originally Posted by Ronnie

Is he coming to the swarm in February? If so I will be there and would look at.

Thank you for the offer, Ronnie. We do not know if we will be in Florida or Texas during the Swarm. We would like to go, as long as logistics allow.