Howling noise in new mb 3500 ex

[Mikessh]

I have a brand new sprinter 3500 dully cargo van with less than 500 miles which i bought to do a van conversion, i hear howling noise coming from the rear at certain RPM, dealer thought noise came from the driver side of rear axel and replaced the driver side axel shaft with no avil, noise still there, any idea?
Is this a common issue with these vans?
Have not started the conversion yet other than sound proving and plywood on the floors which didnt help with the noise!

 

[Tom Tint]

Are you talking about a howling noise at about 70MPH that resonates through the whole van ?

 

[Mikessh]

Are you talking about a howling noise at about 70MPH that resonates through the whole van ?

Howling noise at different speeds, Which sounds like an old differential!

 

[Naildrivingman]

I have a brand new sprinter 3500 dully cargo van with less than 500 miles which i bought to do a van conversion, i hear howling noise coming from the rear at certain RPM, dealer thought noise came from the driver side of rear axel and replaced the driver side axel shaft with no avil, noise still there, any idea?
Is this a common issue with these vans?
Have not started the conversion yet other than sound proving and plywood on the floors which didnt help with the noise!

I have exactly the same issue and the same van and just 200 miles more than OP. The noise was worse when I first got it. I recall it pretty much occurred at all speeds and it seemed to migrate from side to side. I’ve yet to report it to the dealer. I figured I would get to 1000 miles and if there is still a noise I would schedule a check. I’ve dealt with a lot of new mechanical items in my life. Generally, moving parts need to “bed in” over a relatively short period of time whether they are large or small. I can’t recommend that others follow my lead. One needs to follow his conscience. These vehicles aren’t cheap. Keep the forum informed and I will do the same.

 

[sprintguy]

Does it happen at certain speeds ? Under load? on a Deceleration?
The 3500 Vans tend to make noise. Most of the times it is normal. Let me explain a bit . The rear end is a full floating type rear end, meaning that the axle shafts do not have weighted load on them. The shafts only transmit torque to the wheel. The splined end of the shaft is mated to the differential carrier through the side gears, the hub end is bolted to the wheel hub. both ends are supported by bearing sets. The hub assembly in the rear uses 2 tapered roller bearings on a spindle to support the weight of the vehicle (kinda like the front of an old rear wheel drive car.) therefore replacing the shaft alone would not fix a noise. With all that said because of the amount of bearings in that ear end it tends to make some noise. Now couple that with a large open space where the rear springs are bolted both to the rear end and to the unitized body through a shackle and a torque box. Not to mention that the springs have no more than 3 leafs (one of which may be only a helper). Also the housing that contains the Ring, pinion , pinion mate and side gears has been lightened by removing material in strategic places to decrease unsprung weight to increase fuel economy and emissions.
The most reasonable course of action for diagnosis (at the dealer level ) is to drive another LIKE van and verify if the noise that is heard is in fact a reparable noise or just another characteristic of the total design package.
If the noise is not "as designed" then the dealer does or should have the tools needed to pinpoint the offending frequency to determine the the proper repair. Diagnostics have come a long way but not all techs have the time or the knowledge to use it. Always start with the simple and collect data first.
Good luck and I truly hope your van is "as designed " and all that was needed was some understanding and explanation.

Carl

 

[Mikessh]

Thank you both for the reply and sharing, I have not loaded the van yet the only thing I’ve done so far is the floor (sound deadening pads called Killmat, 1” ISO insulation foam and 3/4” plywood) I’ve also used the Killmat on the walls and ceiling, this has helped a little with the overall noise but definitely not enough, you can still hear the distinct howling sound from the rear when I accelerate and decelerate at certain speeds, mainly around 30 & 60 MPH, the noise is annoying, may be I get used to it! not sure what to expect when I finish the build, would the extra weight be better or worse? Thanks again!

 

[Mike DZ]

This (or similar) has been written about many times. I have a lengthy thread on this forum with my personal discovery voyage. Bottom line, the sound is likely a resonance set up by normal vibration in the engine excitation traveling down the driveshaft and being expressed in the rear axle and amplified by the body. I had rear axle replaced under warranty (no help) and had MB factory techs look at it and provided the science behind my explanation above. Drove a 3500 from the lot, it had the same drone but slightly quieter. I can make the sound disappear by lowering air pressure in rear tires by 15-20 pounds (only for a test). Some 4x4 models can get rid of it with a rear spring change to a softer spring. I used sound suppression by fabricating a panel of wood, foam, and butyl rubber, above the rear axle,. between the frame rails. I have subsequently removed this panel and re-skined the inside of the RV floor with click lock manufactured flooring. Over 50K miles the sound is still there, but not to the heart stopping, what's the number to 911? level it was originally.

 

[Naildrivingman]

Mine exhibited extremely high pitched yesterday upon startup and short distance drive. That day was the coldest I’ve experienced since buying vehicle (-9 F). The harmonics so concisely explained by Mike DZ above make sense to me. Couple that with the cold temp and my observations that the whine lessens as the drivetrain warms with longer trips, makes sense as well. I’ve yet to drive more than 5 miles consistently at highway speed. I believe mine will be better once I can make longer trips consistently. Thanks all.

 

[River Rafter]

2019 pleasureway van camper 45 to55 mph drivetrain hum been to dealer twice normal very annoying noise.From my research it’s a common normal problem that Mercedes can’t solve.Please call Mercedes and complain maybe they will find a solution.

 

[sailquik]

Invest in the factory rear wheelhouse (fenderwell) covers.
The covers really damp out a lot of the rear end noise that gets
broadcast up into the interior by the wheelwell tubs (particularly on
5 series (516/519) 3500 with Dual rear Wheels or Super Singles.
The wheel tubs are huge.
Also the droning noise @ 40-50 mph is often due to an issue with the
driveshaft, not the rear axle.
The frequency of the sound is usually the key to which issue.
If the frequency equates to a rotating shaft, or a wheel, or the axle
each of them has a different frequency at the same speed due to the
gearing and diameters involved.
Hope this helps,
Roger

 

[Ostracod]

2019 pleasureway van camper 45 to55 mph drivetrain hum been to dealer twice normal very annoying noise.From my research it’s a common normal problem that Mercedes can’t solve.Please call Mercedes and complain maybe they will find a solution.

Same experience with 2021 PleasureWay Plateau: rear drivetrain hum at 45 to 55 mph. I took it all the way up the service chain at the local dealer and the response top to bottom was "yes we hear it too, but it is normal for that model." That said, after a couple months use, I don't really notice it anymore. Maybe my brain is more willing to ignore it now that I know it's not a problem that is going to get worse or cause damage. I also spend relatively little time driving at those speeds.

 

[River Rafter]

Call Mercedes at 800 367 6372 and register a complaint maybe they will come up with a fix.

 

[126v8]

Doesn’t the the road vibration damper springs cure it?

 

[kkanuck]

Invest in the factory rear wheelhouse (fenderwell) covers.
The covers really damp out a lot of the rear end noise that gets
broadcast up into the interior by the wheelwell tubs (particularly on
5 series (516/519) 3500 with Dual rear Wheels or Super Singles.
The wheel tubs are huge.
Also the droning noise @ 40-50 mph is often due to an issue with the
driveshaft, not the rear axle.
The frequency of the sound is usually the key to which issue.
If the frequency equates to a rotating shaft, or a wheel, or the axle
each of them has a different frequency at the same speed due to the
gearing and diameters involved.
Hope this helps,
Roger

Do you have a part number by chance for the factory wheel wells 3500 as well as 2500?

 

[Mike DZ]

Doesn’t the the road vibration damper springs cure it?

Don't think we have enough data on the VS30, but based on the previous generation, the answer is that it solves it in only a few of the cases. The MB TSB (previous generation) states that replacement of parts will not resolve it, but an adjustment of driveline angles may reduce it.

 

[sailquik]

Do you have a part number by chance for the factory wheel wells 3500 as well as 2500?

If you have a 2004 T1N, I really can't help as I've never looked for wheelhouse covers for a T1N.
Maybe one of the T1N guru's can find the part numbers for you.
Not the same as the NCV3 or C907/VS30 wheelhouse covers at all.
Roger

 

[hein]

Although not a cure for the source of the noise,
Thinsulate would be a good way to block/absorb it.

If it is the differential then you might even be able
to put a blanket of AU4002-5 above it against the
underside of the floor. It shouldn't get too wet
there but an ABS plastic shield could be added.

The rigid foam under your floor may actually
be transmitting the vibrations and causing
your floor to be a speaker for it.

All the best,
Hein
DIYvan.com

 

[Taylor Marine]

Mine has a howl when decelerating from 50 to 40mph... Definitely differential gear howl. Above 70mph a lovely drone comes alive and when you hit the speed limiter it's like a long bellowing cow kind of howl / honk sound....

Mines a 90% work / 10% play vehicle. Road conditions allow 68 to 78mph. I'm always in the fast lane.... 72/76ish always. If I did 65 I'd have to be in the far right lane.

 

[Dbares]

Are you talking about a howling noise at about 70MPH that resonates through the whole van ?

Just picked up brand new van. First thing I noticed when I got on the highway. Crazy, weird howling noise at exactly 70-75mph. Will talk to dealer tomorrow but right now just chalking it up to common road/wind noise for such a large vehicle I guess?

 

[Tom Tint]

Just picked up brand new van. First thing I noticed when I got on the highway. Crazy, weird howling noise at exactly 70-75mph. Will talk to dealer tomorrow but right now just chalking it up to common road/wind noise for such a large vehicle I guess?

Dealer will look like a deer in the headlights..