Busnut needs assistance in AL

[gumpy]

I just got the following message from a busnut who is having mechanical issues in AL. Can anyone offer advice?

I'll see if I can get more direct contact info. This is all I have so far.

I added his phone number at the bottom. If anyone knows of a repair facility close, please call him and post here.



Hi,

I'm just another guy with a bus problem.

I'm stuck 60 miles North of Birmingham with a tranny problem (probably).

MC-7 with 6V92 DDEC II and Allison HTB 748 tranny.
Do you know anyone I can talk to in the Cullman area?
I can't go more than 10 mph.

Thanks

Bob at 605-545-3454

[luvrbus]

His best bet is going to be WW Williams in Birmingham, that is a tough transmission to find anyone to work on with the translator,hopefully it is just low on fluid they won't up shift when low of fluid the sensor tells the DDEC to go into the low power mode,you got to love electronics    

[Gary Hatt - Publisher BCM]

Yup.  That is one thing about those newer Allison's.  Before they fail completely they will limit your speed until you get it diagnosed and solve the problem so you could at least limp on into a shop.  I had the same thing happen to me until I unplugged the oil pressure sensor. Just kidding.  

Sometimes you just want to go back to the old manual transmissions.  Cliff probably doesn't remember these but when they went out you usually only lost only one gear but you could drive it for quite a while longer before you had to pull it into the shop and pull it and replace a gear, which could generally took a whole day.  But if you were lucky, the only problem was the shifter linkage got stuck when you dropped your half of pint into the shift lever and a broken piece of glass prevented it from shifting.  That is why you always wanted to be sure your shifter boot was in good condition to keep that glass out of there.  

[gumpy]

I passed that on and gave him a couple numbers for WW Williams and a couple bus companies in the area to call.

He sent the following:


Fluid level is good. Was 1st thing I checked.
There is a definite vibration. Almost like a cylinder missing - but only at high idle or something out of balance turning inside tranny.
Torque converter plugged?
When I go 10-15 mph the bus really vibrates BAD but can coast w/no problem at all.
Am changing spin-on tranny filter today.


The problem started right after an aggressive accelleration from dead stop during a hard left.
Does a leveling valve have any role in tranny operation?
Could this be a torque sensor, pressure sensor,,,,.....some sensor with an electrical problem?
Followed the cable from the plug on right side of tranny up to where it goes into a hollow behind th right tag tire.
Do not see the ATEC box in there or anywhere.
Followed a 2nd smaller cable to the ECU atop the engine.


The canon plug on the backside of the shifting keypad is pristine.

[gumpy]

More info...

The vibration is somewhat noticable at high idle while parking brake is set and tranny is in nuetral.
Vibration not present at normal idle, parking brake set tranny in nuetral.
Vibration is baddd at 10-15 mph in drive (under load).
U-joints are tight. No wobble, no movement when tapped w/a 2 lb. hammer.
No movement of tranny yoke or dif. yoke either.

[chessie4905]

Sounds like a torque converter problem.

[jackhanow]

Maybe one of the torque converter bolts fell out.

[eagle19952]

flex plate ?

[gumpy]

So, here's the latest update. You're gonna love this!

===

Pretty sure it's fixed!
It took JD at C & J Bus 30 seconds to figure it out.

A piece of rubber sheet stock came loose inside the compartment that houses the fan gearbox and squirrel cages. The sheet stock ended up inside a spinning squirrel cage causing unbelievable vibration. How much vibration? Enough to cause the shutters on my rear side access doors to shake. Enough to make my main rear engine access doors to visibly shake. Enough to seriously shake the whole bus.

Removed the broken pieces of "flap" and voila'.....everything's fine now.
Haven't taken it down the road yet but am 99% sure it's fixed.

Couldn't have done this without your help.
Tell everyone thanks.

[Scott & Heather]

Well, that was easy


Sent from my iPhone using Tapatalk

[muldoonman]

Wow! You could have had a $5000 dollar bill at some shops with that problem. "Oh Sir, that trans needs a R&R!"