Hey guys, it's me again. You haven't failed me yet and I got another issue with my toy. So the other day I changed out the trans filter and cleaned out the old fluid (no clue how long it had been in there). Got in it today and put it in drive and....nothing. Have aftermarket lokar cable shifter hooked up and the linkage is fine, transfer case is in the right gear, and everything trans is full of fluid. Any ideas, need to drive!!!
Do you have a DEEP pan?
If so, did you put a spacer between filter and valve body suction line?
If you didn't space the filter DOWN to get into the fluid, you can be sucking air ABOVE the fluid in the pan and still show 'Full' on the dipstick.
DID YOU TRY CRACKING A LINE LOOSE TO SEE IF IT'S PUMPING FLUID OR NOT?
If not, I'm guessing the spacer didn't come with your filter kit, and you didn't move the spacer from old filter to new filter...
Just a guess, but I've seen it plenty of times before!
Customers are always relieved when it's just a filter problem and not a $1,500 Trans rebuild
(Since no respectable shop will offer a 'Repair' instead of rebuild and warranty it with the issues a TH-400 has with some internal parts)
If it is pumping fluid, then you start looking at 'Port Pressures' to see if the fluid is reaching the correct spots with sufficient pressure...
The second thing I see once in a while, but not very often, is a SHALLOW PAN, with a 'Deep' filter kit installed.
The filter is socked against the SHALLOW pan since it's spaced DOWN for a deep pan, and the filter simply can't draw enough fluid being smashed against the pan to get things working.
There is a SECOND possibility that doesn't involve filters,
And that is you have shredded the 'O' ring on the center support. This is bad since you have to take the transmissions out and down to fix this problem,
And you will probably need a new drum and center support to fix the issue.
TH-400 is the all time 800 pound gorilla of auto transmissions, but all that strength comes at the penalty of weight in steel inside the transmission.
There is a center support to help handle that weight, and over time, the bushing in the center support gives up and lets the rotating drums come into contact with the NON-Moving center support.
This shreds 'O' rings and the fluid can't reach the clutch drum pistons anymore.
The drum and center support usually have galling wear meaning they have to be replaced also for the transmission to work again.
Didn't get a chance to drop the pan again today, but it is a shallow pan. I actually don't believe that I replaced the o-ring on the pick up tube or remember if there was one on it. The new filter I used came from O'Reilly. I pulled the old filter off put the pick up tube on the new filter and bolted back up the pan. Should have checked the o-ring on the pick up tube again. How deep is the deep pan anyway. Just to be certain.