4r100 in 1999 f350 PSD lazy on the shifts

[99 f350 PSD]

when pulling cattle trailer or with no load the trans does not want to shift like it should seems lazy. i hear what sounds like a hydrolic whine until it gets to overdrive.the trans seems to shift better if your foot is on the floor. just changed trany fluid and filter and that did not help used mercon V.

[RadarRider]

Originally Posted by 99 f350 PSD

when pulling cattle trailer or with no load the trans does not want to shift like it should seems lazy. i hear what sounds like a hydrolic whine until it gets to overdrive.the trans seems to shift better if your foot is on the floor. just changed trany fluid and filter and that did not help used mercon V.

Check your dipstick's yellow pull ring. It'll say either use MERCON or use MERCON V. The reason I ask is because if the stick says to use MERCON, you can't use MERCON V. The reason being is, a good percentage of the 4R100s from e'99 to 2001 were built with a lighter-duty coaster drum version that are found in all E4ODs. Even though it's safe to use MERCON V in most of Ford's transmissions, it doesn't work as well with E4ODs or 4R100s with these outdated coaster drums.

Check your dipstick & let us know what it says. If it DOES say to use MERCON V, we'll move on to the next possibility.

[99 f350 PSD]

it does say to use mercon so i will put mercon in this weekend and see if it helps. thanks for the help

[99 f350 PSD]

will i need to flush the mercon V out some how?

[RadarRider]

Originally Posted by 99 f350 PSD

will i need to flush the mercon V out some how?

You can drain it right from the pan. You'll also need to drain the TC as well, but it's easy. All you have to do is remove the (x4) 10mm bolts that hold the inspection plate at the bottom of the bellhousing. Remove the inspection plate & you'll see your TC. Get a long-handle ratchet or breaker bar with a 24mm socket. Turn the engine CW by the front damper until you can see your drain plug for the TC is pointing straight down. Let it drain until the ATF is a single drip. Replace the plug & the inspec plate & you're all set.

[99 f350 PSD]

thanks i will drain the mecon V and then fill with mercon this weekend and let you know if it helps

[RadarRider]

Originally Posted by 99 f350 PSD

thanks i will drain the mecon V and then fill with mercon this weekend and let you know if it helps

Ok, bro. Good luck!