This site uses analytics cookiesWith your consent we use Google Analytics to understand traffic and improve the site. Declining does not affect any feature.Privacy Policy

HomeProductsFilter AccessoriesFJ-CAP03-CK
EC781 Oil Filter Cap Ford 6.0L 6.4L Powerstroke F-250 to F-550
FJ-CAP03-CK

EC781 Oil Filter Cap Ford 6.0L 6.4L Powerstroke F-250 to F-550

Filter AccessoriesCE / ISO 9001

Replacement oil filter cap for the Ford 6.0L and 6.4L Powerstroke, moulded in the same plastic as the factory part and supplied with a new O-ring. It threads onto the housing on top of the engine and comes off with a 1-3/8 in (35 mm) socket, so the cartridge underneath can be changed without disturbing anything else.

$15.99/ unit · referenceMOQ：1 units
Qty
min 1 units

📋 Key Specs

SKUFJ-CAP03-CK
Part numbersEC781, 1840754C91, 3C3Z-6766-CA
Also replaces1837497C1, RK31821, 904-204
TypeOil filter cap for the cartridge housing on top of the engine
MaterialPlastic, same grade as the factory cap
ColourBlack
Socket size1-3/8 in (35 mm)
ThreadB100 x P3
Dimensions3.98 x 3.98 x 2.8 in (101 x 101 x 71 mm)
Fitment2003-2007 Ford 6.0L Powerstroke F-250 to F-550 Super Duty; 2008-2010 6.4L F-250 to F-550 Super Duty; Excursion 6.0L 2003-2005
Torque25 Nm (18 lb-ft)
SealOne O-ring supplied with the cap
Pack contents1 x oil filter cap, 1 x O-ring
Warranty90 days against manufacturing defects

❓ FAQ

Three signs. A hairline crack at the hex or along a thread flank, which shows as a dark oil line on the housing. An O-ring groove that keeps weeping after a filter change even with a new ring. And damaged threads, usually from a previous service where the cap was cross-threaded or over-tightened. The plastic also goes brittle with age, so a cap that has been on the engine for eight to ten years is worth replacing before it cracks.

Yes. The same EC781 closes the filter housing on the 6.0L from 2003 to 2007 and on the 6.4L from 2008 to 2010, in the F-250 to F-550 Super Duty, plus the Excursion 6.0L from 2003 to 2005. It is not the cap used on the E-Series vans, the F-650 / F-750 or the LCF 4.5L; those take a separately listed cap, so check the number on your original cap before ordering.

1-3/8 in, which is 35 mm. Some workshop guides quote 36 mm for the same cap, so offer the 1-3/8 in socket first and only go up a size if it rocks or slips on the hex. Do not use an adjustable wrench; the plastic hex rounds off and then the cap has to be cut out.

The housing was machined for a plastic cap. Plastic does not conduct heat into the oil the way metal does, it does not corrode against the aluminium housing, and it gives the correct torque-to-seal behaviour at 25 Nm. Billet aluminium caps exist for modified trucks and for owners who have already cracked several plastic caps. On a stock engine the plastic cap is the part the housing was designed around, and over-tightening either type cracks the housing lip, not the cap.

One oil filter cap and one O-ring. The cap is covered for 90 days against manufacturing defects, which covers cracked mouldings, damaged threads and an O-ring groove cut out of position. Every batch is checked for thread form, hex fit and groove depth before it is packed.

MOQ varies by product: 5–100 units for standard parts (see product page). Tier pricing decreases with volume. Custom parts usually ≥ 50 units, evaluated by process.

Stock/short-run: 7–15 days; bulk orders 20–35 days; custom 30–45 days incl. sampling. Note your deadline in the inquiry — sales will confirm capacity.

Add products to the inquiry list and submit with contact info. Sales contact you within 24h and issue a formal quotation (tier pricing + proforma invoice) within 48h. The AI assistant can pre-fill inquiries in chat.

Yes. We develop from drawings/samples and support private labeling. Process: evaluation → sampling (15–25 days) → approval → mass production.

Payment: T/T 30% deposit + 70% before shipment / L/C / Trade Assurance. Shipping: FOB Ningbo/Shanghai, CIF or DDP; EU & NA warehouses; sea/air/express.

ISO 9001 & IATF 16949; CE/UL/ATEX on key products. Every batch ships with inspection reports; third-party inspection (SGS/BV) supported.

Description

Product Overview

The EC781 is the cap that closes the oil filter housing on top of the Ford 6.0L and 6.4L Powerstroke V8. Both engines run a cartridge element rather than a spin-on can, so the cap is not a lid on a throwaway part. It is the pressure boundary that holds the element against its seat and keeps oil inside the housing while the engine runs. This one is moulded in the same plastic as the factory cap, ships with a new O-ring, and comes off with a 1-3/8 in (35 mm) socket.

It fits the F-250 to F-550 Super Duty from 2003 to 2007 with the 6.0L, the same trucks from 2008 to 2010 with the 6.4L, and the Excursion 6.0L from 2003 to 2005. The cap carried over unchanged between the two engines, which is why one part number covers both sides of the 2008 changeover.

Key Features

Same plastic as the factory cap — Moulded in the plastic grade the original cap uses, with the same wall thickness, so it seats and torques the way the housing was designed for. No thread mismatch, no spacer, no interference with the element.
New O-ring in the box — The seal is the part that actually fails first. A fresh ring is supplied so the cap goes back on with a known-good seal rather than a stretched one pulled off the old cap.
1-3/8 in (35 mm) socket — The hex is moulded into the cap, so a standard socket removes it. Nothing has to be unbolted to reach the filter, and no strap wrench is needed on a plastic body.
B100 x P3 thread — Cut to the factory thread form, so it starts by hand and runs down without cross-threading, which is what strips the housing on an aftermarket cap.
One cap for 6.0L and 6.4L — The same EC781 serves both engines, removing the wrong-part risk on trucks that sit either side of the 2008 model change.
A cracked cap weeping oil — The factory cap is plastic and lives in heat and oil vapour for a decade. When it cracks at the hex or along a thread flank, oil weeps onto the housing and down the bellhousing. A sound cap is what stops the leak at its source.
A stretched O-ring after a service — Reusing the old ring is the usual reason a diesel smells of oil a week after a filter change. The ring hardens and takes a set, then seeps. This cap ships with a new one.
Over-torquing the housing — The cap is plastic and the housing is thin. Driving it past spec cracks the housing lip, and then no cap seals. The correct figure is 25 Nm (18 lb-ft), reached by hand first and then with a torque wrench.
Buying an aluminium cap for a stock engine — Billet caps exist for modified trucks. On a stock engine the plastic cap is what the housing was machined for, and it does not transfer heat into the oil the way a metal cap does.

Cross-Reference

Replaces — EC781, 1840754C91, 3C3Z-6766-CA
Ford OEM — 1837497C1
Other interchange — RK31821, 904-204

Specifications

Material — Plastic, same grade as the factory cap
Colour — Black
Socket size — 1-3/8 in (35 mm)
Thread — B100 x P3
Dimensions — 3.98 x 3.98 x 2.8 in (101 x 101 x 71 mm)
Torque — 25 Nm (18 lb-ft)
Pack contents — 1 x oil filter cap, 1 x O-ring

Application

Engine — Ford 6.0L and 6.4L Powerstroke V8 turbo diesel
F-250 to F-550 Super Duty — 2003-2007 (6.0L), 2008-2010 (6.4L)
Excursion — 2003-2005 (6.0L)
Coverage note — The E-Series vans, the F-650 / F-750 and the LCF 4.5L take a cap listed separately; confirm the number moulded on your original cap before ordering
Service note — Offer the 1-3/8 in socket first; some workshop guides quote 36 mm for the same cap, so go up a size only if the smaller one will not seat
Installation — Wipe the housing lip clean, lubricate the new O-ring with fresh engine oil, seat it in the groove without twisting, then hand-tighten and torque to 25 Nm
Warranty — 90 days against manufacturing defects
Batch inspection — Every batch is checked for thread form, hex fit and O-ring groove depth before packing
Quality system — Manufactured under ISO 9001 and IATF 16949 quality management

📄 Downloads

🔗 Related Products