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Northwet1955 · 05-30-2012, 11:10 AM

I have a 2008 W-24 with a MH-1000 tranny. Starting at 50 mph, I can start to hear a whine. It is loudest around 55 and then declines at 60 (can barely hear it after 60). This occurs ONLY in 6th gear. When I flip the switch to 5th, there is immediately no noise. The local allison shop said it is not the tranny. Considering that it does not do it in any other gear at that RPM range and that it vanishes when changed to 5th, I suspect they simply have no idea (they are mainly a big commercial diesel outfit). Before paying good money to some one else, has anyone else had this problem.

edgray · 05-30-2012, 02:25 PM

Quote:

Originally Posted by Northwet1955

I have a 2008 W-24 with a MH-1000 tranny.

Quote:

Originally Posted by Northwet1955

.......The local allison shop said it is not the tranny. Considering that it does not do it in any other gear at that RPM range and that it vanishes when changed to 5th, I suspect they simply have no idea (they are mainly a big commercial diesel outfit). Before paying good money to some one else, has anyone else had this problem.

I don't hink your W-24 has a 1000 series tranny. If you want to KNOW for sure which tranny you have, please post or PM me the last eight digits of your chassis VIN # and I'll get that info for you. If nothing else, call the Allison DISTRIBUTOR, not just an "authorized shop" for a second opinion.

There are many other potential causes for drive-line noise, so I suggest you don't "assume" that it HAS to be the tranny.

Northwet1955 · 05-30-2012, 07:34 PM

Sent vin as a PM.

Picked up the rig within the last year so I welcome any corrections on my assumptions.

I'm not it assuming it can only be the tranny. I've read that the steering pump as also been know to create some noise. WIth ot not occuring in other gears at the same rpm, it seems the most logical starting point. I also called the allison support nuber and they said the tranny should not make such noises and to take it to one of their service centers form their list. No sure the best process to follow thus looking for help.

edgray · 05-30-2012, 08:40 PM

Quote:

Originally Posted by Northwet1955

Sent vin as a PM.

Got it. see my PM reply. Ed

sjholt · 05-31-2012, 06:07 PM

It might be the rear differential howling? My DP does that at 60 mph and at 65 it is quiet.
I put some 80-140 wt synthetic oil in it and it quieted it down.
HTH

Northwet1955 · 06-04-2012, 04:41 PM

Additional information since taking it out over the weekend. Also as Ed indicated, my MH has an M-2100 tranny (same specs as the M-1000 but no parking pawl).

Back to the noise. It is not a steady frequency whine but like a flutter. This noise also goes away when there's no load on the engine (let off the gas) while still in 6th gear.

Any one else have a similar noise and more importantly was the source identified?

edgray · 06-04-2012, 07:47 PM

Quote:

Originally Posted by Northwet1955

Additional information since taking it out over the weekend. Also as Ed indicated, my MH has an M-2100 tranny (same specs as the M-1000 but no parking pawl).

Roland: Sorry but I'm confused by your comment above. I don't see the J72 AAPB listed in your SPID codes. Are you saying yours has the yellow knob instead of a foot-applied Parking brake? Thanks, Ed.

Northwet1955 · 06-05-2012, 09:56 AM

I do have the foot brake. As for the parking pawl, I'm just repeating what the Allison spec sheet (website) states as a difference between the 1000 and 2100. Not that it's germane to the noise issue so just secondary babbling on my part.

edgray · 06-05-2012, 08:22 PM

Quote:

Originally Posted by Northwet1955

I do have the foot brake. As for the parking pawl, I'm just repeating what the Allison spec sheet (website) states as a difference between the 1000 and 2100......

ROLAND: THAT is a good thing! My point is that you DO have a Park Pawl inside the tranny IF you have a foot-applied PB and don't have the J72 AAPB. I did not want to leave the readers thinking ALL 2100s don't include the PP.

By Federal law, the Workhorse chassis built using trannys without a park pawl (both GM & Allisons) were equipped with either the J71 or the J72 and a "yellow knob" and therefore don't have a foot-applied PB.

I'm not sure why the Allison sheet says the 2100 has no PP

. Perhaps that was true of the earlier models and they didn't update that factoid when they added the PP to the "newer" versions.

FWIW, later model year W24s have an Allison MH2350 6 speed, but I don't know what is different about them

.
Ed