If the engine isn't bogging down, I would think maybe a clutch problem.

I don't know anything about a D8H however I wonder if they have a dry clutch or a wet clutch.

If it uses a dry clutch, it is possible it got "wet" so it is slipping. If it is a wet clutch, maybe it isn't a clutch problem. Maybe there is some adjustment to make the clutch clutch tighter.

Anyways, I am not sure it was established whether the engine continues to run at throttle speed when you engage the clutch or if it bogs down and attempts to stall.

It sounds like maybe it maintains throttle speed but the tractor just slows down or stops?

Did you clean the magnetic screen

change all of your filters and cut the old ones to see what is in them,especially the powershift filters. if the transmission pressure is low then the clutch packs won't fully engage and slip. like magnet said"check reverse operation" to see if the symptom is in reverse also. find and clean the transmission screen and magnets. make sure the suction screen is clean.

Reverse is the same as forward. Moves decently in 1st gear but something is slipping once you try 2nd or 3rd. The engine does not bog down at all. I am getting fuel filters today as it doesn't hurt to change them but I don't think it will solve this. I will check the other screens and filters as well. Thanks for some ideas.

sounds to me like the charge pressure on the transmission is low. could be dirty filters low oil or plugged screen and worn charge pump. or the TC as described.

It has to be clutch slipping, right?
Based on everything I've learned, this is the same problem I have with my D7 7m

The series tractor you have has a diesel 3 stage converter followed by a 3 speed powershift transmission. I suggest that you lift the floor plates so that you can watch the driveshaft between the converter and the transmission. If when in gear under full revs the shaft comes to a stop when held with the brakes then that transmission clutch is ok, so systematically go through the gears and forward and reverse to identify if you have slipping transmission clutches or a torque converter problem. This is the most basic test for troubleshooting the issues you are having, will narrow the window of what could be the problem. The transmission only has 5 clutches, 3 speed clutches and forward and reverse clutches.

Wombat

"acejase1234" wrote:

It has to be clutch slipping, right?
Based on everything I've learned, this is the same problem I have with my D7 7m

D8 46 a is a power shift model. You have a hand clutch,or possible a steering clutch problem.

So transmission oil pressure is low based on the guage, it does move around a bit as you shift but the needle stays on the low end, never gets up to normal operating pressure. Oil level is good, I will do filters and screens next I guess.

cut your filters and look for bits of oring or other debris.