Thread: ZF4HP24 Sluggish/Slippy Drive in Forward Gears

Does it come good after a short while? If so, it maybe fluid leaking back from the torque converter.

Originally Posted by V8Ian

Does it come good after a short while? If so, it maybe fluid leaking back from the torque converter.

Ok, so I only drove around the corner and didn't notice it getting much better, I shall try a longer drive and report back. It was almost not moving initially.
Thanks for input, would that mean a seal has failed somewhere?

try this,

let the engine idle for about 15-20 seconds (fills the TC) then manually select first gear. get the vehicle moving to about 10kph select drive and ease up off the throttle to force a change up and then gently accellerate again.

if that works your sprag clutch is on the way out.

If that doesnt work your first gear clutch pack is likely on the way out or the line pressures are low.

try the same thing with the transmission in sports mode.

Originally Posted by Blknight.aus

try this,

let the engine idle for about 15-20 seconds (fills the TC) then manually select first gear. get the vehicle moving to about 10kph select drive and ease up off the throttle to force a change up and then gently accellerate again.

if that works your sprag clutch is on the way out.

If that doesnt work your first gear clutch pack is likely on the way out or the line pressures are low.

try the same thing with the transmission in sports mode.

That makes it sound like either way I'm buggered! I'll give that a shot, thanks.
I may be stuck taking off in first at the worst case or sounds like a new box.

Thanks for the help Gents.

Seems it may just have been low pressure on initial startup. It was idling at around 600-700rpm cold.
I went and raised the idle settings to ~1000 cold, and as soon as it was in D it picked up drive.

I checked the TCU and it was showing gear 1 from dead stop.

you might have a failed strainer O ring or pump seal thats letting the pump suck a little air on start up.

it might be worth checking the fluid condition and level after a cold start, if it comes out frothy the pumps pulling air from somewhere.

IVe had a couple of cases where it was the precursor to the complete failure of the outer pump seal, a couple of weeks after the intial symptoms of sluggish move offs when cold the auto started leaking out the bell housing.

Good luck.

Isn't the line pressure for these ZF's controlled by something to do with the throttle linkage on the EFI?

DL