6F50 Pump

This listing is a new pump drive chain and sprocket set for the Ford 6F50 and 6F55 six-speed transaxle and the GM 6T70 it was designed alongside, referenced by Ford number 7T4Z-7G249-B and GM interchange 24223985. It is the chain plus both sprockets that spin the oil pump, not the pump body itself. Buyers usually need it when an Edge, Flex, Taurus or Explorer suddenly will not move, or when a rebuild comes back together with no line pressure and the chain turns out to be loose or off its gears.

What the drive chain does in a 6F50

In this family the oil pump does not ride on the torque converter hub. Sonnax describes it as an off-axis, chain-driven vane pump: a drive sprocket splined to the converter hub turns a chain, and the chain turns the driven sprocket on the remote-mounted pump. Every bit of line pressure, converter charge and lube depends on that chain. If it stretches, or the sprocket teeth wear, the pump turns unevenly or not at all, and with no pump drive the transmission has no pressure in any range.

Symptoms of a worn pump chain or sprockets

• No movement in Drive or Reverse after the engine starts, with the selector working normally
• Pressure that is low on a gauge in every range
• A no-move right after an overhaul, when the chain was disturbed or the unit was flipped during assembly
• Metal debris in the pan from worn sprocket teeth

How to confirm before you buy

A gauge on the line pressure tap tells the story: near zero pressure with the engine running means the pump is not being driven or is not making oil. ATSG's confirmed fix on a no-move after rebuild found exactly that, traced it to the chain off the pump gears with worn gears, and recommended replacing the pump gears and chain on all high-mileage units. If pressure is present but low, the pump itself may be worn too. For the solenoid and clutch faults that mimic pump problems, read our 6F35 and 6F50 transmission problems guide.

Fitment

The set is listed for Ford 6F50 and 6F55 and GM 6T70 transaxles from the 2007 launch onward, which covers V6 Edge, MKX, Flex, Taurus, Explorer, MKS and MKT on the Ford side. The 6T75 and later revisions can differ in sprocket and chain details, so count the teeth and compare the hub splines on your old parts, or send us your year and VIN to check. Browse the rest of this family on the 6F35/6F50 collection page.

Install notes

• Install the chain and both sprockets as a set; a new chain on worn teeth wears quickly.
• Use the converter hub to help position the drive sprocket during assembly, as ATSG suggests, and do not flip the case repeatedly once the chain is on.
• Inspect the pump vanes and rotor while it is apart; a worn unit can be swapped for our used 6F50 oil pump assembly.
• If the transmission is open for a full overhaul, the 6F50 master rebuild kit covers the seals and frictions.
• Refill with Mercon LV on Ford units and Dexron VI on GM units, then check the level hot.

Is this a complete oil pump?

No. It is the drive chain and both sprockets that turn the oil pump. The pump assembly is a separate part.

Will a worn pump chain cause a no-move?

Yes. If the chain comes off or slips on worn sprockets, the pump stops making pressure and the transmission will not move in any range. ATSG documented this after a rebuild.

Does it fit the GM 6T70?

The listing gives GM interchange 24223985 and fits the 6T70 along with the Ford 6F50 and 6F55. Compare tooth count and splines with your old set to be sure.

Should I replace the chain on a high-mileage rebuild?

ATSG recommends replacing the pump gears and chain on all high-mileage units, since the cost is small compared with pulling the transmission again.

What fluid goes back in?

Mercon LV in the Ford 6F50 and 6F55, Dexron VI in the GM 6T70.

• Ford 6F35 Transmission Problems: Real Causes and the Fixes That Last