FNG with possible wadded trans

G

Griz

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Oct 20, 2015
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So after 15 years of lusting i finaly became the proud owner of a duramax, and on my 29th day of ownership... Heartbreak. I was heading uphill, gave it some foot and bam... Free revs.. Coasted to a stop... Still no power to the wheels.. Noticed gear indicator (D) flashing, no CEL,shut her down... Waited a min, start.. No CEL, no message on display, drop her into drive and were under way 1-2 ok 2-3 ok 3-4 nothing no CEL/messages no flashing D indicator, drop gear selector into 3rd and were moving again, coast the half mile to my house throw her in park, hop out... Very noticeable grinding noise from trans. Shut her down hooked up the FSv2 to check for codes, nothing. Hooked up OBD2 scanner, nothing.

So what im geting to is: Has anyone experianced a simmilar situation? My first thought is i grenaded the c2 in some way. Considering the c2 is only used in 4th &5th, but im perplexed that no codes were thrown. I do have a 2001 TCM could this be the reason for no codes showing up due to a lack of tcm to pcm comunication?

Dont rip me appart guys, im still a FNG, eager to learn, but still green behind the ears when it comes to dmax/allisons.

Thanks in advance.
 
CarolinaHD

CarolinaHD

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Feb 8, 2011
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NC
Had similair issues and it was the transfer case. Eventually it imploded and ripped out the rear seal on the trans, drained all the fluid, and left me stranded far away from home..


Drain the fluid in the case and check it out. Take a magnet to the fluid to see if there's any carnage.
 
G

Griz

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Oct 20, 2015
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Drained T case. There were a few magnesium shavings, but nothing magnetic. Stuck a flexible magnet tool up thru the drain hole and drug it around a bit, came up empty. So then i decided to check the trans, there was a good wadd of magnetic sludge on the drain plug, all verry fine shaving. After draining the fluid, i droped the pan, there were a few chunks of metal in the bottom of the pan, nothing bigger than 1mm

I would expect to find some shavings in the trans, but where do you draw the line between normal wear and tear and "theres a problem"?

Either way T case is coming out sunday
 

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Mike L.

Mike L.

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Maybe I read it wrong. The weird thing is it didn't throw a P0776 code and why the noise after you came to a stop?
 
G

Griz

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Oct 20, 2015
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Mike L. said:
Maybe I read it wrong. The weird thing is it didn't throw a P0776 code and why the noise after you came to a stop?
Click to expand...
The grinding noise while it was in park is one of the main reasons why i thought somthings up with the trans. If it was the T case how would anything be able to move to be able to make noise if the trans is in park and the e brake is set? Wouldnt the parking pawl restrict any rotation of the output shaft of the trans? The fact that no codes came up is what trips me up the most... Could having an 01 TCM in an 05 truck have any effect on codes showing up? I have the stock TCM i could throw it back in and run it thriugh the gears to see what happens, but big part of me says dont do it, you'l only do more damage.

I can understand how while under way this could point to a T case issue, after Mike pointed that out i took some time to sift through threads on Transfer case problems and did some reaserch on the inner workings of the case itself, and if there was an issue with the selecctor fork or its asociated parts that could verry well be the culprit. I dont knownif the previous owner installed a pump rub kit, but judging by the black silicone sealant between the to case halves leads me to belive its been opened up before, so its anyones guess. Or

Sunday will be the day of revalation, i figure youve got to drop the TCase befor you drop the trans, at least ill have a good idea of whats next then, hell who knows mabey lady luck blesses me with 2 issues at the same time.
 
C

Cougar281

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Sep 11, 2006
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St Louis, MO
Since you have the first three gears then then when it shifts to 4th it free revs, I doubt it's the TC. It sounds to me like the planet/hub splines have twisted/stripped. But I could be wrong. But like Mike said, it's odd you didn't get a CEL and trans code.

Sent from my 831C using Tapatalk
 
SmokeShow

SmokeShow

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Nov 30, 2006
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Any chance its an NSBU issue? Mine would intermittently kick out of gear if I didn't start moving within a short time after putting in drive. Only did that once or twice while the truck was actually under power moving though. It wasn't a regular occurrence that did it every time nor did it do it at a specific gear change like the OP is experiencing. Mine never threw a code/CEL though.
 
CaptPhil

CaptPhil

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Sep 10, 2011
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Cougar281 said:
Since you have the first three gears then then when it shifts to 4th it free revs, I doubt it's the TC. It sounds to me like the planet/hub splines have twisted/stripped. But I could be wrong. But like Mike said, it's odd you didn't get a CEL and trans code.

Sent from my 831C using Tapatalk
Click to expand...
If it does that then that is what it is. Happened to me.

Sent from my SM-G900V using Tapatalk
 
S

S Phinney

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Aug 15, 2008
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CaptPhil said:
Who me? No, this trans is solid. Just saying thats what happened to the first Shit build that this truck had.

Sent from my SM-G900V using Tapatalk
Click to expand...
I was wondering. It sounded like you may have hurt it again. That's good that it's holding up we'll.

Sent from my SM-G920V using Tapatalk
 
G

Griz

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Oct 20, 2015
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Your moms basement
End result... Broken trim spring, a $2 part? Witch contributed to the striping of the splines on the p2 planetary, a $1000 part! Moral of the story, if your trans downshifs funky get it checked out before disaster strikes.

A big thank you to Mike L, you were a pleasure to do business with, thank you for the exlent work, the advice, and the great conversations.
 
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Cougar281

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Sep 11, 2006
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With your description, I suspected you had stripped spines. Glad you got it sorted out.

Mike is good people. He's never steered me wrong.
 
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