Duramax Diesels Forum Truck of the Week
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Old 02-12-2018, 08:24 PM
Cloudy Cloudy is offline
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Default Serious shift delays, need help, locals guys have no idea

Okay, some of you might remember my thread about my injection pump blowing up. Well, I'm back with another bizarre issue. I'm certain this POS is cursed, but I can't get it to stay running long enough to sell the thing.

I have a 2006 LBZ. Bone stock. Well maintained (allegedly).

Couple weeks back, truck out of nowhere started shifting at a serious delay, as in it would shift at 2100-2300 RPM. It would also downshift really late, and sort of "jab" into gear on downshift. I pulled over, checked the fluid. Bit on the low side but plenty of fluid. It wasn't new but it was still quite red and did not smell burnt. The trans temp was fine, no overheating. No check engine light came on.

On that same day that started happening, I drove home and noticed a puddle of ATF on the ground where my truck had been sitting, and had idled at for a good 10~ minutes.

I didn't have time to fiddle with the truck, so I let it sit for about three weeks. In that time, no more fluid leaked out of the tranny.

I then put about maybe 1/3 of a gallon of ATF in and got it to a reasonable level, and drove the truck to a local well respected transmission shop. They don't specialize in Allisons by any stretch but do deal with them somewhat regularly.

They hook up their pro scantool, absolutely no codes thrown. They find the leak to be a seal on the top bellhousing bolts (or something of that matter), so the trans gets dropped and those get replaced. They then reset the TCM (I believe), and the transmission goes back to shifting fine at the factory default setting. As well, they do a trans service (drain/fill new fluid, new external filter).

I pick up the truck, pay a hefty bill relative to work performed (something I have become all too acquainted with lately). Truck did shift fine. I drive maybe 80 miles (possibly not even), and the truck suddenly goes back to the exact same late shifting problem. No leaks this time. No codes thrown. I call the trans shop back, they say they have no idea what the issue might be, as it sounds like after being reset to default settings, that the trans is somehow learning this shifting, and are dumbfounded that there are no codes thrown.

Someone on the FB group suggested that if my fuel filter is old/clogged, that can cause the problem. As mentioned in my previous thread, my fuel filter was replaced upon replacement of my CP3 (less than probably 600 miles ago). I do have another new fuel filter I could replace it with but not sure if it'd be worth bothering with if my current filter is that new.

Only other thing I can think of is that I might have one injector that could potentially stand to be replaced, but I'm confused how a crappy injector could cause shifting issues. I did some online searching but haven't read about anyone having a similar problem.

So if anyone can chime in, please do so I can try and point a repair shop in the right direction before anyone decides to just throw parts at it.

Cheers.
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Old 02-13-2018, 07:11 AM
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Chevy1925 Chevy1925 is offline
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what fuel filter did you replace it with? is it plastic?

did the trans shop find anything in the trans pan or did they not even change the internal filter?
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Old 02-13-2018, 08:09 AM
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Try a new fuel filter first. A 600 mile filter could easily be clogged.


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Best 1/8th, 7.29, 98.6MPH (Street tires, fuel only, single Journal bearing GT42 charger) (2010)

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Old 02-13-2018, 08:19 AM
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Can't you bypass the filter for testing?
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Old 02-13-2018, 08:24 AM
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Default Serious shift delays, need help, locals guys have no idea

You can either replace the fuel filter and see if that helps or find someway to monitor sensors on the truck. That way you can see if itís the fuel or some other issue.


I sure wouldnít bypass the fuel filter this point in time. If it is indeed plugged up with only 600 miles on it youíre going to trash the fuel system.

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  #6  
Old 02-13-2018, 08:26 AM
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Quote:
Originally Posted by Mike L. View Post
Can't you bypass the filter for testing?
a length of 1/2" hose could be used to loop around and bypass it for sure
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02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 02-13-2018, 08:30 AM
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Quote:
Originally Posted by Dozerboy View Post
You can either replace the fuel filter and see if that helps or find someway to monitor sensors on the truck. That way you can see if itís the fuel or some other issue.


I sure wouldnít bypass the fuel filter this point in time. If it is indeed plugged up with only 600 miles on it youíre going to trash the fuel system.

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I've done it many times to diagnose a problem. Short drive around the block won't trash anything.
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Old 02-13-2018, 09:41 AM
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The current fuel filter is an oem AC Delco filter. I'll try and get the filter changed. I've been wondering if I should drop my fuel tank and maybe even try and get it cleaned out. After injector and injection pump problems and if it's dirtying a fuel filter within 600 miles something is clearly wrong. I fill up at a local Shell primarily that goes through a lot of diesel so I wouldn't say quality of fuel is necessarily my issue.

I don't believe they changed the internal trans filter. From what I've always read, don't need to unless overhauling the trans. Truck has 170k~ miles on it, and the trans shop guy said transmission seemed to be in perfectly fine condition.
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Old 02-13-2018, 09:49 AM
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Quote:
Originally Posted by Mike L. View Post
I've done it many times to diagnose a problem. Short drive around the block won't trash anything.




Maybe fuel is cleaner in California. But Iíve seen enough nasty stuff come out of the fuel systems on these trucks there is no way I would do it.

Ive seen algae, rust from water contamination, sand, etc. Way to risky to do this in my opinion.


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2003 GMC CCSB LLY
Built by me, tuned by me.

2009 ECI Diesel Truck Points Champion
2010 ECI Diesel Truck Points Champion
2011 ECI Diesel Truck Points Champion
2012 ECI Diesel Truck Points Champion

Big thanks to everyone who helps me.

Best 1/8th, 7.29, 98.6MPH (Street tires, fuel only, single Journal bearing GT42 charger) (2010)

Best 1/8th, 6.93, 104.24MPH (Street tires, fuel only, single HX60 turbo) (2016)

Best 1/8th, 6.60, 106.6MPH (Street tires, fuel only, single HX60 turbo) (2017)
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Old 02-13-2018, 10:11 AM
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Quote:
Originally Posted by Cloudy View Post
The current fuel filter is an oem AC Delco filter. I'll try and get the filter changed. I've been wondering if I should drop my fuel tank and maybe even try and get it cleaned out. After injector and injection pump problems and if it's dirtying a fuel filter within 600 miles something is clearly wrong. I fill up at a local Shell primarily that goes through a lot of diesel so I wouldn't say quality of fuel is necessarily my issue.

I don't believe they changed the internal trans filter. From what I've always read, don't need to unless overhauling the trans. Truck has 170k~ miles on it, and the trans shop guy said transmission seemed to be in perfectly fine condition.
well unfortunately, that is incorrect. If you ask Mike, the service interval was designed around the 01 allison which had a metal screen as the internal filter and did not filter near as well as the paper media all 02-up allisons got. that filter should be changed every 30-50k depending on abuse. it will pack up over time and starve the pump of oil.
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James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 02-13-2018, 10:40 AM
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If the sump filter never needs changing; why didn't they use a straight pipe instead of a filter?
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Old 02-13-2018, 03:10 PM
Cloudy Cloudy is offline
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Is this a serious issue if it is not changed? According to the service records and corresponding receipts I received, it has been serviced regularly with fluid and external filters. Doesn't appear the internal was ever changed but if the general consensus among non-trans experts is don't bother with the internal filter, I would think this issue would be much more prevalent. I bet a lot of guys with 200-300k on their trucks don't even know there is an inner filter and never have issues with it.

I don't mean to put words in anyone's mouth, but from my understanding of talking to the local transmission guy, he seemed to think that the Allison's are sensitive enough that if it started having shifting issues because of an inner transmission issues or low fluid or whatever, it should have thrown a bunch of codes. That is what has him perplexed, and believes it to be something other than the transmission cause it to want to learn shifts to be so late. He also seemed to think the fluid leak was just coincidence.

If you guys fully believe that an inner filter change has a fair chance at solving this problem, I'll give it a shot. Otherwise, I'm not going to bother doing something like a inner filter change that, while probably smart for long term ownership, is a waste of money because I don't want to own this truck a second longer than once it is running properly. This is bar-none the worst vehicle I have ever owned and most days I wake up hoping someone steals the damn thing and trashes it.

At least I finally know what it's like to own a 6.0L Ford. Lol.
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Old 02-13-2018, 03:24 PM
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IOWA LLY IOWA LLY is offline
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A waste of money to change a filter. Get outta here dipshit.


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__________________
2003 GMC CCSB LLY
Built by me, tuned by me.

2009 ECI Diesel Truck Points Champion
2010 ECI Diesel Truck Points Champion
2011 ECI Diesel Truck Points Champion
2012 ECI Diesel Truck Points Champion

Big thanks to everyone who helps me.

Best 1/8th, 7.29, 98.6MPH (Street tires, fuel only, single Journal bearing GT42 charger) (2010)

Best 1/8th, 6.93, 104.24MPH (Street tires, fuel only, single HX60 turbo) (2016)

Best 1/8th, 6.60, 106.6MPH (Street tires, fuel only, single HX60 turbo) (2017)
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Old 02-13-2018, 03:38 PM
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Quote:
Originally Posted by Chevy1925 View Post
well unfortunately, that is incorrect. If you ask Mike, the service interval was designed around the 01 allison which had a metal screen as the internal filter and did not filter near as well as the paper media all 02-up allisons got. that filter should be changed every 30-50k depending on abuse. it will pack up over time and starve the pump of oil.
Cloudy , you might have missed this , 30000 to 50000 k !!!
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Old 02-13-2018, 03:43 PM
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Never hurts to change the sump filter, but it will not cause late shifting. It can cause slipping. Engine problems will cause late shifting.
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