Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!

1 - 7 of 7 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 · (Edited)
Hi there! I hate asking questions, but I've searched and can't find a definitive answer. Here goes:
I have a 2008 duramax with 90,000 miles. About 3,000 miles ago I did EFi live, transgo jr w/ relearn, both trans filters, alligator cooler lines, dpf/egr delete, and uppipe. I only use my truck for hauling stuff and 4 wheel drive weather. I towed a 10k lb trailer all summer long after doing the mods and the truck worked flawlessly. Then it sat for 6 weeks until the first day of bad weather. It was 20 degrees out and the truck slammed into gear when i put it in drive. While driving it would slam into 2nd, 4th, and 6th upshifting and downshifting. I thought it must just be getting used to the cold weather so I started driving it more to see if it would get better. Well a 1,000 miles later I would say it's worse. Now it sometimes feels like my face is going to hit the steering wheel when it downshifts to 4th (while decelerating). It will also flare shift 2nd and 4th under light acceleration.
Just seems strange that the problems are only on the even gears. It also really slams into gear hard while going to drive or reverse. Fluid level is perfect, not burnt. No codes yet, but I want to get this fixed before it gets to that point. Thank in advance!
 

·
Registered
Joined
·
507 Posts
this may sound dumb, but try putting a bottle of seafoam trans tune in it.Mine would have harsh 3 to 2 down shifts, and within 10min of putting that in my truck it resolved whatever it was. I figured it was more than likely something getting a bit stuck, and this free'd it up. Its cheap, mine as well give it a shot. make sure the trans temp is nice and warm when youd o this, and drive it around right afterwards for a good while.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #4 ·
I definitely plan on dropping the pan this weekend and taking a look at the valve body. Thank you for the seafoam suggestion but for me "miracle fluids" are usually more of a last ditch effort.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
Dropped the pan. Nothing obvious yet but I thought it was strange that the filter was sitting in the pan when I dropped it. Is not like the filter had actually fallen out, i think the seal is just loose. The seal was still in the housing also. I put the filter back up and it wouldn't hardly stay up on its own. It's a Pro-king fk-345. Also my spin on filter is a driveworks. I'm thinking I should get some oem filters and put it back together
 

·
Registered
Joined
·
129 Posts
did you check all the trim valves and make sure they all move freely. the problem is probably a sticky shift valve as mike l stated
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #7 ·
That will be tomorrow's project. A storm blew just as I got the pan down. Should I take this opportunity to switch to synthetic fluid like the actual allison stuff? I've just been running Napa fluid in it.
 
1 - 7 of 7 Posts
Top