Symptoms
Late or harsh shifts, a flashing overdrive light, or dark, burnt-smelling fluid.
The fix, step by step
- Drop the pan, change the filter, clean the pan and magnet, and refill with Mercon V, which the factory manual quoted on Bronco Zone specifies for the E4OD.
- A pan drop only replaces about 8.5 of the roughly 16 quarts, so repeat the job, or add a drain plug or a deeper pan, to replace more of the old fluid.
- If you find particles or white (water-contaminated) fluid, get it diagnosed before you refill it.
- Read any stored codes if the O/D light flashes.
Tools & part numbers
- Drain pan
- sockets
- gasket scraper
- funnel
- torque wrench.
Where to buy the parts
Motorcraft E4OD transmission filterBronco Graveyard ↗Amazon ↗
B&M Hi-Tek deep aluminum pan, E4OD/4R100Bronco Graveyard ↗Amazon ↗
Motorcraft Mercon V automatic transmission fluidBronco Graveyard ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Ford Full-size Bronco parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.