I drove my "new" 98 Disco about 30 miles today to see if the transmission did slip when warm as the seller to Bro-in-law had said, and after 10 miles or so at 55 it felt like it was "hunting" going in and out of overdrive. Our 1999 Dodge Grand Caravan did that and I fixed it with a replacement used solenoid (did all of them while I was in there) so I am thinking the Disco may have the same problem of a dodgy solenoid.

On the way home I drove in 3rd for awhile and it seemed to shift normally, and then I shifted back to Drive about 10 miles from home I didn't feel any hunting after that. This is all on two lane roads at 45 to 55.

I am considering trying a filter and fluid change with Lucas Transmission Fix added in the refill before I do any mechanical trans work. Has anyone else had the OD solenoid kicking in and out situation, or any idea if Lucas Trans fix would even effect OD solenoid function?

 

The ZF 4HP22 contains zero solenoids, hydraulic pressure, valves, governor do the shifting. The valves do stick and valve seals can be replaced. When it was hunting you should've been @ 50-52mph when you noticed 4th. It won't shift into 4th until you hit the 50mph mark so it'll stay in 3rd until then. 4th gear is the "F" clutch. Post up what you find when you drain the pan. I wouldn't replace the filter right away, just the fluid. See if there's any sparkles....

Generally you can snag these auto's for $250 or less.

 

I was probably driving right around 50 to 55; would it "hunt" if you were driving steadily close to the kick in point?

Do you mean drain it through the drain plug or pull the pan? (most of my other vehicles don't even have a drain plug on the tranny so the disco makes it easier).

 

Yes it would. You know now that you mention it I do stay either just under or over the shift point when I drive because it's second nature, a learned habit.

Yep, through the drain plug. If you have a fair amount of sparkles it's better to just leave the filter in place. The clutch discs won't fail as quickly, leave them something to grip with. The drain plug is magnetized so you'll know how bad the clutches are.

 

OK, thanks. I assumed it is best to have the transnission warm when you drain it? Or does it matter?

 

Doesn't matter, either way you get most in the pan.