4R100 Transmission Cooler, new and ready to install. Fits the 4R100. Ships fast from the USA.
A 4R100 behind a 7.3L Power Stroke, a 6.8L V10 or a 5.4L in a Super Duty, Excursion or E-Series van lives a hard life when it tows. If you are seeing the transmission temperature climb on long grades, getting an overtemp code, or feeling the converter clutch slip and flare once the truck is heat-soaked, more cooling capacity is the cheapest insurance you can buy for that unit. This kit, as pictured, is a remote-mount plate-and-fin cooler supplied with braided hose, hose ends and adapter fittings, so it can be plumbed in alongside the cooler that is built into the radiator.
Fluid leaves the converter circuit hot, runs out of the case to the cooler, and returns to lubricate the geartrain. On the 4R100 that circuit matters more than it did on the older E4OD. Sonnax's technical bulletin on 4R100 flow issues explains that the 4R100 uses modulated converter clutch control, which prioritizes pressure to the converter clutch apply over flow to the cooler, so cooler flow is higher before lockup and drops while the clutch is applied. Ford added an external cooler bypass to the 4R100, a ball, seat and spring that opens around 60 psi of cooler head pressure, because a restricted cooler on this unit hurts converter clutch performance. A cooler that flows freely and sheds more heat keeps the fluid in the range where the converter clutch and the overdrive and coast clutches hold properly.
Start with fluid level and condition, then look at the cooler circuit as a whole. A kinked, crushed or weeping line, a radiator cooler packed with debris, or a stuck bypass valve will all cause the same heat complaint, and an add-on cooler will not fix a line that is restricted. Our E4OD cooler line replacement guide walks through checking flow and head pressure and explains why the 4R100 behaves differently from the E4OD on a flow test. If the truck also shifts badly when cold, read EPC solenoid symptoms first, since low line pressure produces slip that heat only makes worse.
This kit is listed for the 4R100, the updated E4OD that Ford used from 1998 in F-250 and F-350 Super Duty pickups, F-450 and F-550 chassis cabs, the Excursion and E-Series vans. A remote cooler is not a casting-specific part, but the connection is: line ends changed over the production run, so check whether your truck has threaded fittings or quick-connect ends at the radiator and case, and match the adapter fittings in this kit before you cut or disconnect anything. Also check where you plan to mount the core, because space ahead of the radiator differs between the diesel, the V10 and the vans. Send us your year and VIN if you want help, or browse the E4OD and 4R100 parts page for everything else we stock for this unit.
The usual layout puts the remote cooler in series after the radiator cooler, on the return line to the transmission, so the fluid gets a second pass of cooling before it goes back to the case. Mount the core in clean airflow, keep the braided hose away from exhaust and sharp edges, and secure it so it cannot chafe. Blow out the existing lines and radiator cooler with compressed air before hookup if the old fluid was dark or there was any clutch debris. Leave the factory bypass in place. Top up with Mercon V, then check the level hot and re-check every fitting for seepage after the first drive. If the fluid already shows slipping damage, a cooler alone will not bring the clutches back; a 4R100 banner rebuild kit or a fresh 4R100 solenoid kit may be the real repair, with the cooler protecting the work afterward.
| Fits | 4R100 |
| Part type | Transmission Cooler |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is a remote cooler meant to be added to the circuit, normally in series after the radiator cooler on the return line, so the fluid is cooled twice before it returns to the transmission.
The kit includes braided hose, hose ends and adapter fittings as pictured. Line ends on the 4R100 changed over the years, so confirm your fitting style at the radiator and case before installing, or send us your year and VIN.
No. The 4R100 bypass is there because this unit's converter clutch control is sensitive to cooler restriction. Leave it in place and make sure it is not stuck.
Use Mercon V. After installing the cooler, fill and check the level hot, because the new core and hoses hold extra fluid.
If the slip only shows up hot, more cooling can help. If the clutch slips cold or the fluid is already burnt, diagnose the converter clutch, EPC and line pressure circuits first.
