Rumble Strip Noise Help Needed

I first posted this in Doktor A's original RSN fix thread but didn't hear from anyone..

Anyways, I have a 2005 T1N 3500 Sprinter that I've converted into a campervan (quite a heavy load) with RSN symptoms that are beginning to get bad. At least I think they are RSN symptoms which I will describe below...

For the last 6 months the noise was occurring during acceleration when shifting up. It was quite rare at first, so I didn't make a note of at what RPMs it was occurring (probably at around 20 mph). For the past couple weeks it has gotten MUCH WORSE and I hear the vibration and noise immediately after accelerating from a stop. The noise goes away once I hit about 1000 RPM. It definitely sounds like going over rumble strips. The noise comes back at the same RPM level when I'm decelerating.

I'm a little bit confused for two reasons:
1. From my research it seems that it is common for the noise to be at higher speeds and RPM (around 40mph and 2000 rpm). In my case the noise is gone at this speed.
2. Sometimes the noise will continue on idle. It is not as 'rumble-stripy' as the acceleration noise, but there are definitely harsh vibrations going on. I couldn't find any other cases on the forum where the vibrations continued at idle. Has anyone seen this before?

Any help would be appreciated. If it is fact RSN does anyone know of any mechanics in the PNW (preferably Vancouver) area that are capable of helping with the issue? I don't think I have the skills to tackle Doktor A's fix on my own

Do you have someone who can drop the pan for you or an auto shop that can work under instructions at hand.
I can ship you a modified end plate and you should be able to find the basic servicing kit at your end with fluid..
Dennis

lindenengineering said:

Do you have someone who can drop the pan for you or an auto shop that can work under instructions at hand.
I can ship you a modified end plate and you should be able to find the basic servicing kit at your end with fluid..
Dennis

Click to expand...

Yes I have a local mechanic that should be able to follow the instructions. Do you believe my symptoms are RSN? The noise is occurring at lower RPMs compared to the others I read on here. Also, are you able to elaborate where I can find the basic servicing kit?

Thanks.

Basic service kit is just filter, gasket, and fluid (9 quarts with t/c drain, 4 with just the pan) Shell ATF-134 or equiv.
Lots of sources...

-dave

Nautamaran said:

Basic service kit is just filter, gasket, and fluid (9 quarts with t/c drain, 4 with just the pan) Shell ATF-134 or equiv.
Lots of sources...

-dave

Click to expand...

I forgot to mention I just got a tranny service done about a month ago.. They replaced the filters, fluid and connectors. Will I need to do this again with the RSN fix?

Thanks.

Oooo... what fluid was it filled with?
If it wasn’t MB 236.12/236.14 Approved you may have your answer.

The NAG1 is very sensitive to fluid properties, and the T/C clutch all the more so.
ATF+4 goes into a lot of Dodge vehicles but is not the right fluid for a Sprinter...

-dave

Atf4 will rapidly bring on rsn. Personal experience, fixed with shell 134.

Nautamaran said:

Oooo... what fluid was it filled with?
If it wasn’t MB 236.12/236.14 Approved you may have your answer.

The NAG1 is very sensitive to fluid properties, and the T/C clutch all the more so.
ATF+4 goes into a lot of Dodge vehicles but is not the right fluid for a Sprinter...

-dave

Click to expand...

Uh oh. Just called the tranny shop and they said they put Dexron VI into mine. Checked on MB website and I don't see it listed under the 235.12 or the 236.14. Are these symptoms common for the wrong fluid?

Yes

Your symptoms are not identical to RSN symptoms, mostly slow deceleration/coasting with light pedal press only. You need to replace all the fluid and stop going to the place that serviced your tranny incorrectly

NelsonSprinter said:

Your symptoms are not identical to RSN symptoms, mostly slow deceleration/coasting with light pedal press only. You need to replace all the fluid and stop going to the place that serviced your tranny incorrectly

Click to expand...

Yes funny because they are a transmission specialist.. think they'd know what fluid to use. I'm bringing it back to them this week to swap out the fluid. I'd go somewhere new but would have to pay for another service.

Let your shop know that NAPA has reasonably good prices for Shell ATF-134.
A case of 12 quarts was th same as 9 bottles, and would give them enough for a full pan and t/c drain and fill, with enough left for a second pan drain and fill (though they should be able to tie into the cooling lines and flush it properly?)

-dave

NelsonSprinter said:

Your symptoms are not identical to RSN symptoms, mostly slow deceleration/coasting with light pedal press only. You need to replace all the fluid and stop going to the place that serviced your tranny incorrectly

Click to expand...

Can you provide a good description of RSN symptoms? Or maybe a reference to such a description?

Thanks

lindenengineering said:

Do you have someone who can drop the pan for you or an auto shop that can work under instructions at hand.
I can ship you a modified end plate and you should be able to find the basic servicing kit at your end with fluid..
Dennis

Click to expand...

How much are you asking for the part? I’ve got a rumble on deseleration low rpm shifting torwards a stop sign.

rustdogbrown said:

Can you provide a good description of RSN symptoms? Or maybe a reference to such a description?

Thanks

Click to expand...

RSN is a low-frequency rumble through the drive train that occurs at slow engine RPM when the van is (essentially) coasting in gear at slower residential speeds. It is generally agreed (?) to be caused by a resonance between the torque converter clutch and its control solenoid, and perhaps a line or two of missing computer code in the transmission control module. Changing throttle position will usually interrupt the rumble. The DARF modification drills a relief port through the transmission valve body's end plate, preventing the resonance from setting up, though the duty-cycle of the control solenoid is increased as a result.

-dave

The rumbling is very similar to driving over the 'wake up' divots/pits alongside many roads. In its most severe form, it can appear even under medium throttle. Most users report it on decel in 1-2-3, especially with light throttle. RSN in 4-5 or under medium throttle is a sign of poor fluid condition, or wear in the TC.

The RSN symptom can show at different times. Another range that I have noticed is around 41 - 42 mph in 5th. 3.727 differential. That is with DARF mod.

Some discussion of RSN and shudder is here.

Rumble Strip Noise Transmission Drive Train Shudder
https://sprinter-source.com/forum/showthread.php?t=5027

vic