6T40 Pump

This is a remanufactured Gen 3 oil pump for the later GM 6T40 family, tagged 6T40, 6T41 and 6T46. If your 2015-or-newer Cruze, Malibu, Equinox or similar GM front-driver runs hot, will not lock the converter, engages slowly, or shows low line pressure, the Gen 3 pump is a known wear point. It is not interchangeable with the earlier converter-driven pumps.

What the pump does in a Gen 3 6T40

For the 2015 model year GM redesigned the 6T40 pump to save fuel. The older Gen 1 and Gen 2 pumps were driven off the torque converter. Gen 3 moved the pump off the converter centerline and drives it by chain, and it uses a variable vane design that cuts its flow, and the power it takes from the engine, when demand is low. Transmission Digest and Sonnax both point to one new feature as the trouble spot, the lube-on-demand valve. Below about 87 psi it stays closed and lube feeds through one orifice. Above 87 psi it opens a second orifice and doubles cooler and lube flow while the converter clutch is applied. The valve is always moving, and the pump bore it rides in wears from side loading.

Symptoms of a worn Gen 3 6T40 pump

• Converter clutch that will not apply, or applies and slips
• Low cooler flow, overheated fluid and an overheated converter
• Reduced line pressure, felt as slow engagement or soft shifts across the range
• A whine that follows engine speed
• Repeat overheating or converter trouble after other repairs

How to confirm before you buy

When a Gen 3 unit has converter apply trouble, low line pressure or a lube and cooler flow complaint, Transmission Digest recommends vacuum testing the lube-on-demand valve bore. Worn castings have been found that pulled 0 in-Hg. That bore leak sends converter feed straight to exhaust, and the result looks like a failing converter, a bad TCC solenoid or a weak pump. Check the fluid hot at the level set plug before anything else, then compare commanded and actual pressure. Our 6T40 valve body symptoms guide helps separate pump problems from control problems, and 6T40 common problems and fixes covers the rest of the family's failures.

Fitment

This pump is listed for the Gen 3 6T40, 6T41 and 6T46. TransGo lists the 6T31 and 6T51 as Gen 3 designations as well, but this listing does not name them, so send us your VIN before ordering for one of those. Gen 3 started with the 2015 model year, and it carries on in late models such as the 2025-2026 Trax and Envista (RPO MNH/MNK). If your unit is an earlier Gen 1 or Gen 2 6T40 or 6T45 with the converter-driven pump, this is the wrong part. Use the converter-driven 6T45/6T40 pump instead. Match the casting on your old pump, or send year and VIN and we will confirm. If the converter-area seals are being replaced at the same time, the 6T40 pump seal installer set seats them square.

Install notes

• Install the drive chain and sprockets in good condition, and check the sprocket bearing surfaces for wear before reassembly.
• If the old pump overheated the unit or shed debris, flush or replace the 6T40 transmission cooler. A restricted cooler brings back the same overheating.
• Fill with DEXRON VI. GM lists a 4.0-6.0 L fluid change capacity for the 6T40. Set the final level hot, at 85-95 C, at the level set plug.
• For a full overhaul with the pump out, the 6T40E/6T45E master rebuild kit covers frictions and seals. Confirm it lists Gen 3 coverage for your unit.
• Clear adaptives and complete the adaptive learn afterward.

How do I know if my 6T40 needs the Gen 3 pump?

Gen 3 started with the 2015 model year. These units carry tags such as 6T41 and 6T46 and use a chain-driven pump that sits off the converter centerline. Earlier converter-driven units need the Gen 1/Gen 2 pump. Send us your VIN if unsure.

What is the lube-on-demand valve?

A valve in the Gen 3 pump that doubles cooler and lube flow above about 87 psi when the converter clutch is applied. Its bore wears, which can leak converter feed to exhaust and cause overheating and converter apply problems.

My converter clutch will not apply. Is it the pump?

It can be. A worn lube-on-demand bore in the Gen 3 pump bleeds off converter feed. Vacuum testing that bore is the recommended check before replacing a converter or TCC solenoid.

What fluid does the 6T40 use?

DEXRON VI. GM lists a fluid change capacity of 4.0-6.0 L. After a repair, set the level hot at the level set plug instead of filling by volume.

Does it fit a 6T31 or 6T51?

This listing names the 6T40, 6T41 and 6T46. For a 6T31 or 6T51, send us your VIN and we will confirm before it ships.

• 6T40 Valve Body Symptoms: What Wears, What It Does to the Drive, and How to Test It
• 6T40 Common Problems and Fixes
• 6T40 Delayed Engagement: Causes and Fix
• 6T40 Fluid Change Cost