Threads into the 5R55W/5R55S fill plug on Ford Explorer, Ranger, Mountaineer and Explorer Sport Trac so you can pump ATF up into the pan from below without a dealer fill tube.
If you have the pan down on a 2002-or-later Ford Explorer, Explorer Sport Trac, Mercury Mountaineer or Lincoln Aviator and just realized there is nowhere to pour the new fluid, this is the part you are looking for. The 5R55W and 5R55S five-speed automatics behind those trucks were built without a dipstick or a fill tube. Fluid goes in from underneath, through a small check plug in the bottom of the pan, and Ford's answer to that was special tool 307-437. This brass adapter does the same job as 307-437 and the OTC 6604, and it costs a fraction of what a shop charges just to top the fluid off.
On these transmissions the drain plug in the pan has a smaller fluid level check plug threaded into its center. Ford's service procedure for the 2002 Explorer and Mountaineer calls for removing that inner plug with the engine running, then threading in a fluid fill tool and pushing ATF up into the pan with an oil suction gun or pump. The adapter is that fill tool. One end threads into the check plug port, the other end is a barbed nipple that takes an ordinary fluid pump hose. The barb on this version is shaped to grip the hose so it does not pop off when you lean on the pump handle. Without it you are stuck trying to hold a bare hose against an upside-down hole while fluid runs down your arm.
Getting the level exactly right is not optional on a 5R55. Low fluid starves the pump, and the 5R55 family already has a known weak spot: the overdrive and intermediate servo pin bores wear, bleed off apply pressure and produce slipping and gear ratio codes such as P0735. Running it a quart low makes those symptoms show up sooner. Overfilling is just as bad. Installation guidance for these units states that overfilling is the number one reason these transmissions appear to leak from the converter housing, because the extra fluid is pushed out of the vent. Owners often chase a front seal that was never bad.
Check the level before you buy anything else. The Ford procedure has you watch transmission fluid temperature on a scan tool, idle the engine, cycle the shifter through each range and return to Park with the truck as level as you can get it. Remove the check plug with the engine running. A thin stream or a drip means the level is correct. If nothing comes out, pump fluid in through this adapter until it does. If you still have shift complaints with the level verified, work through our 5R55 harsh or delayed shift diagnostic walkthrough before replacing hard parts, since solenoid body faults and servo bore wear share many of the same symptoms.
This adapter is listed to fit the Ford 5R55W and 5R55S in 2002-up Ford Explorer, Explorer Sport Trac, Ranger, Mercury Mountaineer and Lincoln Aviator applications, and it replaces Ford 307-437, OTC 6604 and IOE2037. The check plug design is the deciding factor, not the badge on the tailgate, so look under your truck: if the drain plug in the transmission pan has a smaller plug in its center, this is the tool for it. The 2002 Ford procedure removes that plug with a 3/16-inch hex key, and some remanufactured units use a T30 Torx plug in the same spot. If you are unsure which transmission you have, send us the year and VIN before ordering. You can browse everything else we carry for this family on the 5R55 parts page.
Keep the adapter with your shop tools. You will need it again every time the fluid is serviced or a leak needs a top-up, and it fits any 5R55W or 5R55S in the family.
| Fits | Ford 5R55W, 5R55S (Explorer, Ranger, Sport Trac, Mountaineer, Aviator) |
| Replaces | Ford 307-437, OTC 6604, IOE2037 |
| Material | Brass fitting |
| Connection | Threads into fill plug port, barbed hose end |
| Ships | From the USA |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. Neither transmission has a dipstick or a fill tube. The level is set and fluid is added through a small check plug in the center of the pan drain plug, which is where this adapter threads in.
It is a replacement for Ford special tool 307-437 and OTC 6604. It performs the same job: it threads into the check plug port and lets you pump fluid into the pan through a hose.
Use Mercon V ATF. Ford lists about 12.6 quarts total capacity for the 5R55W/S, but a pan-and-filter service takes much less. Set the final level by the check plug procedure with the engine idling and the fluid warm, not by the quart count.
Any hand fluid pump or suction gun with a hose that fits the barbed end works. Bottle-top hand pumps and lever-style fluid pumps are both common choices.
It is listed for the Ranger along with the Explorer, Sport Trac, Mountaineer and Aviator. Check under the truck first: if the transmission pan drain plug has a smaller check plug in its center, the adapter fits. If your pan has no such plug, send us the year and VIN and we will confirm.
Check the level first. Overfilling a 5R55W or 5R55S pushes fluid out of the vent and makes it look like a converter housing leak. Drain to the correct level at the check plug before replacing any seals.
