- First Name
- Mathieu
- Joined
- Sep 15, 2022
- Threads
- 9
- Messages
- 1,030
- Reaction score
- 2,036
- Location
- Vassar, MI
- Vehicle(s)
- 2022 Maverick XLT FX4, 1992 Corvette 6-speed
- Engine
- 2.0L EcoBoost
- Thread starter
- #1
My truck just rolled 25k miles. Today I changed the transmission fluid (partial change, really), PTU fluid, and RDU fluid. These were quite simple and anyone with some basic hand tools should be able to do them. About the only two things you'd need to pick up at Harbor Freight or some auto parts store are a fluid pump (for the PTU and RDU) and a long neck funnel.
With the transmission fluid, you're essentially draining it, filling it back up, then leveling it off with the leveling plug on the side of the case near the drivers' side CV axle. Draining the fluid is just like draining the engine oil, there's a bolt (14 mm) on the bottom of the transmission that comes out pretty easy. This bolt/plug has a seal built into the flange.
The interesting part is filling the transmission back up. I've read some very helpful threads here (thanks to those who have posted them!) but the one thing I would change is actually removing the entire transmission vent (which is where you're filling from), which means removing the entire airbox. The vent has a rubber neck with a vented cap on top, held on by a spring clamp. Some suggestions were to just pull the cap off and place the funnel into the rubber neck. This method is very restrictive and it would take a long time to get the fluid in. Below is a pic of the restrictor at the bottom of this neck:
While it might seem daunting, removing the entire airbox is the best bet to gain full access to this vent tube and just remove the whole thing (which is actually specified in the Ford service manual). The airbox is only held on by two plastic clips on the air dam where the "ram air" tube starts, the hose clamp holding the intake tube to the box, then three grommets below the box. With the two clips up on the air dam removed and the hose clamp loosened, the entire box just lifts right out (unplug the MAF too). Only takes about a minute altogether. The vent tube and spring clamp was now very easily accessible. You'll need a pair of needle nose pliers to pinch the clamp and remove. The tabs on the clamp were facing the engine block, so upon reinstallation I rotated the whole assembly to face forward for even easier access next time (I'll be doing this every 25k miles).
Transmission took about 5.5 quarts of Mercon ULV. I initially put 4.5 quarts in, warmed up the truck, and gently drove around the block. Upon pulling the leveling plug (10 mm hex/allen) with the truck running (remove the front drivers' wheel) and lowering the jack to what would be normal ride height, it was low/nothing came out. Added a little more than a quart and upon pulling the plug again, fluid was coming out. I let it fall down to a slow stream/trickle then screwed the plug back in. In this process, I'd say a few ounces came out. I've seen some say 4.5 quarts, others take a whole 6 quarts, so I think it's just a case-by-case basis. Overall, pretty easy and with no hiccups should take about 45 minutes to an hour.
EDIT: I'll add for the RDU and PTU fluid changes, I just used the spec Motorcraft fluids. 75W85 Hypoid Gear Oil for the PTU, then 75W Rear Disconnect Drive Oil for the RDU. Both of these were as simple as drain, replace drain plug, then fill until fluid comes out of the fill hole. PTU drain plug was a standard 3/8" ratchet/square drive, PTU fill plug was an 8mm hex/allen and was accessed through the passenger side wheel well with the wheel removed. RDU drain and fill plugs were both standard 3/8" ratchet/square drive.
I did not teflon seal any of the plugs. The RDU plugs actually appeared to have some sort of sealer on the threads from the factory, so I just wiped off the plugs but did not remove the sealer, then snugged them up. None of these plugs require a lot of torque, I just choked up on the ratchet handle and tightened to snug.
RDU took a little less than a quart, I think I had about 4 or 5 fl-oz left in that bottle. The PTU took 0.5 qt.
With the transmission fluid, you're essentially draining it, filling it back up, then leveling it off with the leveling plug on the side of the case near the drivers' side CV axle. Draining the fluid is just like draining the engine oil, there's a bolt (14 mm) on the bottom of the transmission that comes out pretty easy. This bolt/plug has a seal built into the flange.
The interesting part is filling the transmission back up. I've read some very helpful threads here (thanks to those who have posted them!) but the one thing I would change is actually removing the entire transmission vent (which is where you're filling from), which means removing the entire airbox. The vent has a rubber neck with a vented cap on top, held on by a spring clamp. Some suggestions were to just pull the cap off and place the funnel into the rubber neck. This method is very restrictive and it would take a long time to get the fluid in. Below is a pic of the restrictor at the bottom of this neck:
While it might seem daunting, removing the entire airbox is the best bet to gain full access to this vent tube and just remove the whole thing (which is actually specified in the Ford service manual). The airbox is only held on by two plastic clips on the air dam where the "ram air" tube starts, the hose clamp holding the intake tube to the box, then three grommets below the box. With the two clips up on the air dam removed and the hose clamp loosened, the entire box just lifts right out (unplug the MAF too). Only takes about a minute altogether. The vent tube and spring clamp was now very easily accessible. You'll need a pair of needle nose pliers to pinch the clamp and remove. The tabs on the clamp were facing the engine block, so upon reinstallation I rotated the whole assembly to face forward for even easier access next time (I'll be doing this every 25k miles).
Transmission took about 5.5 quarts of Mercon ULV. I initially put 4.5 quarts in, warmed up the truck, and gently drove around the block. Upon pulling the leveling plug (10 mm hex/allen) with the truck running (remove the front drivers' wheel) and lowering the jack to what would be normal ride height, it was low/nothing came out. Added a little more than a quart and upon pulling the plug again, fluid was coming out. I let it fall down to a slow stream/trickle then screwed the plug back in. In this process, I'd say a few ounces came out. I've seen some say 4.5 quarts, others take a whole 6 quarts, so I think it's just a case-by-case basis. Overall, pretty easy and with no hiccups should take about 45 minutes to an hour.
EDIT: I'll add for the RDU and PTU fluid changes, I just used the spec Motorcraft fluids. 75W85 Hypoid Gear Oil for the PTU, then 75W Rear Disconnect Drive Oil for the RDU. Both of these were as simple as drain, replace drain plug, then fill until fluid comes out of the fill hole. PTU drain plug was a standard 3/8" ratchet/square drive, PTU fill plug was an 8mm hex/allen and was accessed through the passenger side wheel well with the wheel removed. RDU drain and fill plugs were both standard 3/8" ratchet/square drive.
I did not teflon seal any of the plugs. The RDU plugs actually appeared to have some sort of sealer on the threads from the factory, so I just wiped off the plugs but did not remove the sealer, then snugged them up. None of these plugs require a lot of torque, I just choked up on the ratchet handle and tightened to snug.
RDU took a little less than a quart, I think I had about 4 or 5 fl-oz left in that bottle. The PTU took 0.5 qt.
Sponsored
Last edited:
