allison loosing pressure after sitting for 2wks. [Archive]

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mark g

01-20-2003, 15:03

any updates since i posted this problem 6 month ago? if the truck sits over 10 days i have to wait till the trans builds pressure before it will go. after that its fine until another long break. if i try to go immediately it goes to limp mode and sets a code. its a d/a built 12-01. the dealer here in austin has not seen the problem(henna chev-austin,tx)truck has 19k miles. any help?? thanks,mark

SteveO

01-20-2003, 18:34

markg,

The problem your taling about is called "Loss of Prime". What's happening is the Converter is draining back, when this happens the Converter pumps a volume of air through the Cooler circuit then it's picked up at the Pump.. The Pump looses fluid for a few seconds at this time. If you move the gear selector at this time the pump does not have pressure to apply the proper clutches.. And you know what happens...

This is normal if the truck sits for more than 5 days.. The best thing to do is to start the truck up wait about 30 seconds then cut it off.. Restart and it will have purged the air out...

The alternative is to replace the trans... That's up to you and the dealer...

mark g

01-20-2003, 18:51

so i guess gm has not acknowlegded this problem?

SteveO

01-20-2003, 18:55

markg,

You need to have your Dealer call TAC and see what they say...

Since the truck is still under warranty it's up to GM if they want to replace the trans..

Like I said, GM say's it's normal if the truck sits for 5 days before this happens...

[ 01-20-2003: Message edited by: SteveO ]</p>

mackin

01-20-2003, 20:21

Oh how that sounds reminiscent to the "A QUART IN 1000 MILES IS ACCEPTABLE OIL CONSUMPTION" answer too !!!!!

When only but a few do it ..... Shame on GM.....

MAC :(

mdrag

01-20-2003, 21:02

SteveO,

Just curious if there is an explanation why this seems to occur in some Allison equipped trucks and not others? I have a late '01 and I've parked for 5 - 10 days on more than a few occasions and never had this happen. The truck is parked on a very light incline with the front end higher.

dcpdave

01-21-2003, 11:56

fyi,
the converter drainback issue is being addressed. replacing the trans at this time may not fix the concern. g.m. has identified the cause of this as a converter spring, and "lube valve spring". basically, the current springs are not strong enough to keep the fluid from draining back. g.m. expects to have revised springs out sometime in feb., and will issue a tsb to us. i will try to keep everyone posted as to when the repair becomes available.
hope this helps,

SteveO

01-21-2003, 17:09

dcpdave,

The fix your talking about is already out, since GM Dealer's are not allowed to go any further than replacing front seals I did not mention the fix..

Allison issued an SIL back in November, ALL transmission built after 6310234829 Indy and 6320154492 Baltimore have the new springs...

Lube Regulator Spring>> 29540523
Converter Relief Spring>> 29541296

The two springs cost about 50 cent...

IMO>> I do not like the idea of GM dealerships doing anything internally in these transmissions, that includes replacing these springs.....

Why do some do it and others do not.. I think it's because of the lack of mileage.. The more mileage and the more the vehicle is broke in, the better and the less likely for this to occur..

mdrag

01-21-2003, 20:38

SteveO and dcpdave,

Thanks for the explanations.

mdrag

mark g

01-22-2003, 07:15

thanks,guys

jjackson

01-22-2003, 07:41

I read these posts yesterday, and last night started my D/A after sitting for 2+ weeks (I only use it to pull our 13K 5th wheel)and did not experience this problem (thankfully). I've got 4200 miles on mine.

John

dcpdave

01-22-2003, 09:04

steveO,
i wasn't aware of the allison bulletin. we just got the info from g.m. from an "emerging issues" seminar broadcast last thursday. they indicated that they will have another seminar in feb., when they make parts available, and show how to replace them.
i understand your concern of dealers doing the work, since we have not been allowed to go into these transmissions yet, so it will be new to us. but, i'm confident that g.m. will give us the nessessary info to repair, and most g.m. transmission techs are very good. i don't think that you will find a "general" tech going into these transmissions.

SteveO

01-22-2003, 16:13

JJ-Dmax,

Your transmission was probably built after the Spring changes...

To verify all you have to do is crawl under the truck, Passenger side toward the rear of the trans.. Serial# will start with "63????????" (and 8 more numbers) if your's is after what I have listed above, then it has the New springs, if not then so be it.. Like I said, mine has never done it...

dcpdave,

Hope your right...

oyazi

01-23-2003, 02:01

SteveO ~ chkd mine and it bearly missed the improved spring series. However, while under there, the date format on the label is confusing. Says: 02013. Just what does that tell me?

Thank you

DmaxMaverick

01-23-2003, 02:35

oyazi

That's the Julian date for Jan 13, 2002.

02 is the year. 013 is the day of the year. 032 would be Feb 1, etc.

The date system is not very accurate, but is used by many manufacturers, and the military. Your date could also mean Jan 13, 1902, but I doubt it.