Allison Transmission

Cardinal camper · 02-13-2014, 03:08 PM

I have a 2001 Chevy with allison tranny. Occasionally when I start engine and engage trans in drive it acts as trans us in neutral. I can turn off engine and restart and transmission works perfect. May not do again for week or so. Any ideas?? Thanks in advance!!

Ford Idaho · 02-13-2014, 03:16 PM

When was the last time you had the transmission serviced, filter and oil?

avolnek · 02-13-2014, 03:33 PM

Sounds like you need to have it serviced. Have them change the fluid and refill. While the pan is off they should be replacing the filter as well as adjusting the bands.

Adjusting the bands is important as the trans gets more and more miles on them! The bands will hold on to rotating drums in the transmission to allow things to shift from 1-2 as well as another to allow it to go from forward to reverse. There are very specific procedures to take when doing this...

May also just be low on trans oil. may be plugged filter, could be lots of things... I would definitely suggest having it looked at if you are not comfortable with it on your own.

Cardinal camper · 02-13-2014, 04:27 PM

Just had serviced. All new filters and fluid. No problem before this

TURBS · 02-13-2014, 04:33 PM

Quote:

Originally Posted by Cardinal camper

Just had serviced. All new filters and fluid. No problem before this

What type of fluid did you use?

TURBS

Goshen is my playground.
The last man standing also has a sharpie

Cardinal camper · 02-13-2014, 04:44 PM

Shell Spirax MD3

Ditchooker · 02-13-2014, 09:50 PM

recheck your fluid level, I find they seem to purge some air out of the system once you get it through the gears for the first time after service, and they tend to be very sensitive to fluid level (even 1 litre will make a difference)

Cardinal camper · 02-13-2014, 09:56 PM

Ok tks. I do think the fluid may be a little over full.

MillerTime · 02-13-2014, 10:05 PM

I think that the manual states to use Dex III only. For best results I would recomend that. Not even DEX IV is recomended.

oops. forgot to check mark that stupid box again!

MillerTime · 02-13-2014, 10:07 PM

Oh and usually if this happens like you stated, the fluid is usually low. They seem to jump or become more jerky if over filled.

oops. forgot to check mark that stupid box again!

Ditchooker · 02-13-2014, 10:13 PM

Allisons use the cold setting for rough levels and are best checked when the transmission is at normal operating temp.

avolnek · 02-13-2014, 10:30 PM

Should be checked at normal operating temp as well as in neutral.

Do you know if your shop flushed the trans fluid or drained and replaced? I'm not a fan of flushing because if you flush the fluid then you purge the trans of small fibers from the clutches within that grip. Flushing these fibers cause the clutches to slip more for a while till those fibers are built back up.

PrairieBoy · 02-13-2014, 10:32 PM

My Dad's first Duramax with the Allison transmission did something like that. You would start the truck and put it in gear and the gear display would be blank. The transmission would not work at all. Shut the truck off and start it again and it might work this time and it might not. He had the dealership come and tow it back to them on 3 occasions, the last time they had it for 10 days. The reason they gave the last time was that a clump of mud must have knocked the connector loose. He traded it in on a newer Duramax and the trouble has never returned. Can't remember what year the truck was but it was in the first year that the truck was offered with the Allison transmission.

Cardinal camper · 02-14-2014, 10:12 AM

It was drained, filter replaced, and refilled

jevanb · 02-15-2014, 11:09 PM

Never heard of Shell Spirax MD3 if it is not TES295 approved fluid get it out as fast as you can, also no flushing allowed on this trans no matter what anybodys shop says, just the double drain method is good..
When determining whether or not a fluid is TES 295 approved, look and/or ask for one of two things: The Allison TES 295 approval number and have the Allison Logo. Or you can use what you want but dont expect the trans to live long life

Sounds like the NSBU switch (Neutral Start Back Up) switch. symptoms could be PRNDL display may not show up or only a partial display, no engagement even though your shifter is in D or R (like you were in neutral), codes, or shift range inhibited on the DIC display, easy fix and part cost about 75.00 at a local allison dealer , do not get one at the GM dealer because they charge like 250.00. BTW 06-up 6 speed transmissions no longer use an external NSBU switch

Quote:

Originally Posted by avolnek

While the pan is off they should be replacing the filter as well as adjusting the bands.

their are no bands to adjust on the allison transmission, the clutch packs are set at install..Internally, the transmissions have three planetary gear sets controlled by 5 sets of clutches, labeled C1-C5. 2 clutch packs (C1-C2) are rotating, and transfer input torque to certain elements in the planetary sets, while the remaining 3 sets (c3-C5) are stationary and lock each of the ring gears and their coupled components to the case when engaged. These transmissions contain no bands, sprags, or roller clutches - all gear changes are accomplished by direct clutch-to-clutch changes.

golfmedik · 02-16-2014, 04:47 AM

Another vote for the NSBU switch. My '01 truck is having similar issues with the display too. All I've talked to say this is the problem, just have not had time to get to it yet. Plus the transmissions DO NOT LIKE a lot of fluid. If it is over halfway on the stick while warm, mine will puke some at interstate speeds after 100 miles or so. It won't do it again after it gets down to the warm fluid level being at the half mark.

Cardinal camper · 02-16-2014, 09:00 AM

Thanks for the reply. What is double drain??

jevanb · 02-16-2014, 09:26 AM

Quote:

Originally Posted by Cardinal camper

Thanks for the reply. What is double drain??

drain, replace spin on filter, and do it over again, IMO transynd is the only fluid that should be installed, but amsoil Torque-Drive is also a very good, If you have a w.w.w williams close by you can get the fluid for 170.00 for 5 gals and the NSBU switch

Cardinal camper · 02-16-2014, 09:48 AM

Do you know how many Qts I need. I think I'll replace the fluid. Should I replace the spin on the second time or reuse. Also do you drive between drainings? Tks

jevanb · 02-16-2014, 10:24 AM

Quote:

Originally Posted by Cardinal camper

Do you know how many Qts I need. I think I'll replace the fluid. Should I replace the spin on the second time or reuse. Also do you drive between drainings? Tks

if I remember right ( I run a deep pan) it is 8qts for a stock pan, just remove the spin on and drain it and reinstall, here is some good reading http://www.duramaxforum.com/forum/tr...-transynd.html

To change the switch look here

http://www.youtube.com/watch?v=E6oRDCOviBU

You may also like: