Another rear end noise thread.

I've read through all 4 pages that I could find when searching for "rear end noise" but decided to make a post about mine.

I have been trying to figure this out for the past 4-5 days now. Sound is a constant humming not a high pitch type of noise. It doesn't whine on acceleration or deceleration its constant after roughly 5 mph and is present up until 80 mph without changing pitch or loudness. I have replaced the differential fluid with the Mopar 90 SAE at 102,000 mi which was 1,000 miles ago the noise was present before the fluid change as well but not as noticeable because the van had a partition that I removed. I have taken a few trips trying to pinpoint the noise listening around the cargo floor. Seems like most of the noise is coming from the center of the floor not towards the sides I was kind of hoping its a wheel bearing. I have lifted the van one rear wheel at a time and tried listening to wheel bearing, carrier bearings, pinion bearing and drive shaft hanger bearings with a stethoscope not 100% sure I got a good listen to the hanger bearings because the are surrounded by rubber mount and all the metal parts are moving so can't really get a good place to press down the tip of the scope. I am only getting slight noise from the differential. But when I replaced the fluid everything looked fine. Open to any suggestions as well as recommendations for a good drive line shop around Fresno, CA. I think worst case scenario I am gonna try rebuilding the differential but want to make sure its done right. Also when I tried getting both wheels of the ground the ASR kicks in any way to disable that for testing purposes. I can't really give the van any throttle when on jack stands.

What is the frequency of your vibration?
Does it increase as you go faster?
Does the frequency change when you downshift/upshift from 5th gear to 4th gear?
Engine RPM and driveshaft RPM are the same when you are in 4th gear.
Drive shaft is turning slower than the engine (0.83:1) when you are in 5th gear.
If it's a steady droning sound with a frequency about the same in 4th gear as the engine sound, then it's more likely
the carrier bearing (s) or bad U-Joints than the rear differential.
If it a slower droning sound (the back of your Sprinter, without the partition is like a great big drum) could be wheel/tire
imbalance related.
Are you sure you are not hearing the fuel cooling coil in front of the fuel tank vibrating.....easy to test, stick a small piece of
wood in to wedge it slightly and stop if from vibrating. This phenomenon is often caused by the fuel pressure regulator on the engine.
Hope this helps,
Roger

sailquik said:

What is the frequency of your vibration?
Does it increase as you go faster?
Does the frequency change when you downshift/upshift from 5th gear to 4th gear?
Engine RPM and driveshaft RPM are the same when you are in 4th gear.
Drive shaft is turning slower than the engine (0.83:1) when you are in 5th gear.
If it's a steady droning sound with a frequency about the same in 4th gear as the engine sound, then it's more likely
the carrier bearing (s) or bad U-Joints than the rear differential.
If it a slower droning sound (the back of your Sprinter, without the partition is like a great big drum) could be wheel/tire
imbalance related.
Are you sure you are not hearing the fuel cooling coil in front of the fuel tank vibrating.....easy to test, stick a small piece of
wood in to wedge it slightly and stop if from vibrating. This phenomenon is often caused by the fuel pressure regulator on the engine.
Hope this helps,
Roger

Click to expand...

It's more of a constant sound not a vibration. Vibration suggests two objects vibrating against one another. This is a constant noise doesn't change pitch at any time. But I'll try the 4th / 5th thing. I have been considering wheel tire and will get them balanced out because the tires that came on the van seem like they have been on there for 3-4 years. Never knew about the fuel cooling coil I will check that out as well. Thanks

Still interested in hearing other suggestions for checking bearing etc when on stands. I want to be able to run the van up to speed but the ASR won't let me...

Have a look at your exhaust manifold gasket.
If any of the studs are broken (a fairly common problem) the gasket gets loose and flaps making sound something like what you describe.
Also, do you have a backup camera?
My '06 had a backup camera with sound, and if you didn't turn the sound off.... it made some strange noises.
Kind of alarming until I figured out that whenever I heard something that could not be traced to a vibration
somehow it was probably that the sound on the back up cam was turned on.
Roger

Hi halexh,

Thanks for sharing your findings. When did you first notice this noise?

My T1N has had a steady drone or whine when driven ever since I bought mine at 112k. The noise could be similar to the noise you describe. But I first noticed the sound only after I removed the factory bulkhead.

Our vans have roughly similar mileage. My van has the factory wood floor plus 3/4" thick rubber mats that I assume quiet noise some. At 114k, I replaced the differential fluid using the correct MB spec oil. The old fluid was pretty good, no metal, just brown. I didn't hear any obvious change in noise at that time... but it was well before I removed the bulkhead.

At this point, I'm unsure this noise isn't normal, or if it indicates a problem. I have no easy way to compare it to a similar van. Is it possible it is simply normal engine, road and tire noise exacerbated by the fact a van is a big echo chamber?

hulagun said:

Hi halexh,

Thanks for sharing your findings. When did you first notice this noise?

My T1N has had a steady drone or whine when driven ever since I bought mine at 112k. The noise could be similar to the noise you describe. But I first noticed the sound only after I removed the factory bulkhead.

Our vans have roughly similar mileage. My van has the factory wood floor plus 3/4" thick rubber mats that I assume quiet noise some. At 114k, I replaced the differential fluid using the correct MB spec oil. The old fluid was pretty good, no metal, just brown. I didn't hear any obvious change in noise at that time... but it was well before I removed the bulkhead.

At this point, I'm unsure this noise isn't normal, or if it indicates a problem. I have no easy way to compare it to a similar van. Is it possible it is simply normal engine, road and tire noise exacerbated by the fact a van is a big echo chamber?

Click to expand...

I believe our situations are quite similar. I actually remember reading one of the threads you posted in/started and it sounded pretty much to what I was experiencing but I didn't see a follow up/solution.

A bit more info to clear things up hopefully sharing information might help you as well. I purchased the van with 99,XXX miles on it and drove it back from Little Rock, AR it had a few boxes in the back for the trip back close to 2000 miles and the original partition was in place. Didn't notice the noise. When I got it home I started servicing the van and after getting the transmission fluid changed as well as engine oil. I turned my attention towards the interior. At 102,XXX I took the partition down as well as the flooring and remember driving the van for 3-4 weeks without anything in it while I was working on it. I would use it to go and get supplies etc. I noticed there was a lot of noise but figured it was mainly from the lack of flooring insulation so after completing all the work on the interior I though the flooring would soak up the noise.It helped but I can still hear it. I will add pics of the way I did my floor to give you an idea of how persistent the noise is.

After I got all my flooring in and there was still a drone / humming sound. I changed the diff fluid with the Mopar SAE 90 stuff and just like you didn't find any metal shavings in the diff it looked very clean. Only issue was that it only took 1600 ml but I am assuming I didn't drain it properly because I checked twice and both times fluid came dripping out of the fill hole. The second time the van was even parked with the front approximate 1 inch lower than the rear trying not to spill fluid everywhere.

Anyways as of right now I have gone under the van with a mechanics stethoscope and the only noise I am getting is from the diff but its not loud it just sounds like parts rotating. I want to be able to get the van up to speed while the rear end is on stands but I can't seem to get the ASR to let me do that.

Flooring finished will be moving on to walls later on.

Thanks for the pics. I didnt see captions (using my phone). For some reason I thought you had a blue 118.

The stethescope method is a great idea. I assume you already tried to disable the ASR using the dash button without success.

Have you let someone else drive it while you ride in the back listening and tracing noises? Both our vans still lack any sound containment over the wheel wells. The wheel tubs may be amplifying road noise / reflected drivetrain sounds into the cargo area.

Knowing that many Sprinters travel 400,000 miles or more on the original motor I still wonder if there's nothing wrong with our drive lines, and we are hearing a noise other folks are not bothered by.

hulagun said:

Thanks for the pics. I didnt see captions (using my phone). For some reason I thought you had a blue 118.

The stethescope method is a great idea. I assume you already tried to disable the ASR using the dash button without success.

Have you let someone else drive it while you ride in the back listening and tracing noises? Both our vans still lack any sound containment over the wheel wells. The wheel tubs may be amplifying road noise / reflected drivetrain sounds into the cargo area.

Knowing that many Sprinters travel 400,000 miles or more on the original motor I still wonder if there's nothing wrong with our drive lines, and we are hearing a noise other folks are not bothered by.

Click to expand...

Yup had the ASR disabled via button but I can't help but think there is a way to completely disable it for diagnostic purposes. I will wait for someone to chime in that knows of a way.

As far as the wheel wells. I put 5 coats of the sound deadening stuff the I put on the floor and plan on using some of the sound deadening mat down the line.

I've taken a couple rides with my ear stuck to the van floor. But the sound amplifies and sounds like its coming from everywhere. The worst was behind the rear axle if I had to specify one area. Otherwise it was just balanced all over.

I went out and bought a infrared thermometer and also plan on trying that to see temps after a drive.

I'll post back with results. I know its not normal because my other van although its a 3500 but its same dimensions was completely gutted and didnt make this much noise. It had a distinct diff whine in between 49-50 mph.

AGAIN IF ANYONE KNOWS HOW TO REV UP THE VAN WITH THE REAR WHEELS OFF THE GROUND ????

halexh said:

AGAIN IF ANYONE KNOWS HOW TO REV UP THE VAN WITH THE REAR WHEELS OFF THE GROUND ????

Click to expand...

Sorry I don't have the answer. I really thought the ASR could be fully disabled, temporarily, with the dash switch.

Obviously you know there are speed sensors on all four wheels, so if all four are not turning near the same MPH then the ASR must think the rear wheels are spinning and mess with the brakes. Thus your excellent question of how to disable ASR for diagnostics.

Maybe you can call and speak to Andy Bittenbender (aka Doktor A)?

Another crazy idea - removing all the brake calipers and putting a spacer between the pads would remove the brakes from the equation. Not sure what else the ASR might do, though. Might ASR still limit RPM?

hulagun said:

Another crazy idea - removing all the brake calipers and putting a spacer between the pads would remove the brakes from the equation. Not sure what else the ASR might do, though. Might ASR still limit RPM?

Click to expand...

That actually sounds like a good idea I have the rear end on stands anyway might as well take the discs off and give it a try. When I tried getting it up to speed with the ASR disabled via the switch I don't think it was limiting the RPM's enough to stop me from testing but the constant abs brake action is what made it impossible to get the drive train spinning fast enough.

On a side note does the ASR use the abs pump to actuate the brakes ? If so would having the rear wheels in the air and getting the brakes to pulse be a good alternative to the "GRAVEL ROAD BRAKE FLUSH" not sure if the fluid moves through out the abs pump even though only the rear calipers are being activated. ASR is rear only correct or does it correct with front brake like VW ESP does ?

ESP stability control works all 4 wheels independently.
ASR works on the rear wheels. So it's the ASR that needs to be defeated to run your wheel speed.

Putting your Sprinter up on jack stands and trying to hear a noise in the rear end sounds dangerous to me.
What if it shakes (wheel balance) and falls off the stands. Seems the guy underneath listening would be crushed or run over.
Why not get a small (cheap) recorder and tape it to the rear end or near the rear end on the body and then play the recording?
If your noise does not change frequency as you increase your speed, it's almost for sure not the drive shaft or the differential
gears.
All rotating assemblies in your Sprinter absolutely will change to a higher frequency the faster you go.
As they spin faster, the freq. increases....end of story.
Could be the fuel cooling coils are vibrating....that would be a constant to the greater degree as it's freq. is dependent on the
fuel rail and HP fuel pump relief valves.
Could be some other completely unrelated electrical device that is constant and does not change freq.
Roger

The description of the T1N ASR refers to spinning wheel. ESP controls all wheels.

The suggestion of replacing the "gravel road" may have merit. Between the standard option ESP, BAS, with ESP replacing the brake load distribution mechanical lever system I personally believe that the NAS 2004 and newer models cycle the hydraulic pump/unit more often than the older model years. The fluid residing only in one area and never circulating may have changed.

Some info is here.

https://sprinter-source.com/forums/showthread.php?t=13202

vic

I have it on 2 (3 TON floor jacks) and 4 (stands) and front wheels are chocked. Its not going anywhere.

I like the recorder idea. That's gonna be the first thing I try as soon as its off the stands.

The fuel cooling coils are clipped in their clips but I can't imagine them making the drone/humming sound I am hearing and as I said it seems to be coming from the rear of the vehicle.

Also would it be easier to remove the wheel speed sensor then the suggested brake caliper removal ?

I've had a rear end noise too, put it on 1 floorjack (my stands were too high or too low, depending on my jacking point, so no other solution).

Disabled the ASR through the button too, and it didn't stop blocking the wheels.. in first or second gear (not sure). But when going into higher gears, it actually stopped blocking and I could analyse my rear end noise.

Be careful though. We were quite aware of the danger so nobody was underneath nor in a dangerous position. But 2,5 tonnes don't fall of a floorjack that easily neither I think.

Just fyi, good luck.

Was a solution ever found?

Get yourself an inexpensive IR thermometer that has a laser dot on it and can go up to 200* or so.
Drive the van for a bit then start pointing the thermometer at things like the wheel bearing areas, the pinion bearings, carrier bearings, drive shaft carrier bearing, etc.

That will tell you where your issue lies. Noise like that means heat is being generated.

Sure thing, not currently experiencing this exact issue but more-so was curious of the outcome for these fine folks.