5L40E Overhaul Kit 2000

If your BMW 3 Series, X5 or Cadillac CTS automatic is leaking at the pump or tail seal, slips once it gets hot, or takes a long pause before Drive engages on a cold morning, the hard parts may be fine and the rubber is what has given up. This 5L40E overhaul kit is the gasket and seal set for 2000-and-later GM 4L40E, 5L40E and 5L50E units, the job you do when the case is coming apart for a reseal or a rebuild. It is built without pistons, so you reuse your original clutch pistons and fit new lip seals to them.

What the overhaul kit does in a 5L40E

The 5L40E builds all five forward ratios from a single Ravigneaux gearset. Each clutch pack is applied by fluid pressure pushing on a piston, and that pressure has to travel from the pump, through the case and the rotating shafts, into the drums without escaping. Sealing rings on the shafts and support hold the feed circuits, lip seals on the pistons hold the apply chambers, and gaskets and O-rings close off the case, pump, valve body and extension housing. When those parts harden or wear after many heat cycles, pressure leaks off under load and the clutches slip even though the friction material may still be serviceable.

This kit renews that sealing side of the unit. It is a seal and gasket kit, not a friction kit: frictions, steels, bushings and a filter are not part of it. The older description on this listing said frictions and steels were included, and that was wrong. If your teardown shows burnt or glazed plates, budget for clutch packs as well, or step up to a kit that includes them, such as the 5L40E master rebuild kit.

Symptoms that point to tired seals

• Fluid on the front of the case or at the rear extension housing
• Slipping or a flare between gears that gets worse as the fluid warms up
• A long delay into Drive or Reverse after the car has sat overnight
• Low line pressure readings with a pump that measures within spec
• Reverse, direct or coast clutch damage on teardown; worn pump sealing rings are a documented cause in this family

How to confirm before buying

Check the fluid level and condition first, because a low or burnt fill makes every symptom above look the same. Our transmission slipping diagnosis guide walks through reading pressure and slip behavior before you pull the unit. If the shift problems are electrical or happen only on certain shifts with clean fluid, the valve body may be the real fault rather than the seals. Once the unit is apart, look at the sealing rings and piston lips: flattened, grooved or hard seals plus clutches that still measure within limits is exactly where this kit fits.

Fitment

The kit cross-reference covers the 4L40E, the 5L40E (RPO MX5 and M82) and the 5L50E (RPO MV3 and M22) from 2000 on. Applications on that list include BMW 3 Series, 5 Series, X3, X5 and Z3, the Cadillac CTS, STS, SRX and XLR, Pontiac Solstice and G8, Saturn Sky, and Holden and Opel models. The listing title says 2000 because that is where this design starts; it is not a single-year part. GM and BMW both changed details over the run, so read the ID tag on the left rear of the case, compare the gaskets and seals to your old parts, or send us your year and VIN before you order. Later units are also covered by the separate 2002-and-up 5L40E overhaul kit, and the full range is on our 5L40E and 5L50E collection page.

Install notes

• Soak paper gaskets and lip seals in clean ATF before assembly, and lube the sealing rings with assembly gel so they stay centered in their grooves
• Inspect each piston bore for scoring; a new seal will not save a damaged bore
• Air check every clutch apply circuit before the valve body goes on
• Inspect the direct/reverse housing for cracks while it is out
• Replace the filter and pan gasket with the 5L40E/5L50E filter and pan gasket kit
• Flush the cooler, fill with the fluid specified for your vehicle, and reset adaptive values as covered in our adaptive relearn guide

Does this 5L40E overhaul kit include frictions and steels?

No. It is a gasket and seal kit built without pistons. Frictions, steels, bushings and the filter are separate. If your clutches are worn, add clutch packs or choose a master rebuild kit.

Will it fit my 2004 BMW or Cadillac even though the title says 2000?

The kit is listed for 4L40E, 5L40E and 5L50E units from 2000 on, so a 2004 unit is inside that range. Because details changed over production, compare the gaskets to your old parts or send us your year and VIN to confirm.

What does without pistons mean?

You keep the original clutch pistons and install the new lip seals on them. Inspect each piston for cracks or a damaged sealing surface before reuse.

Does it fit the 5L50E all-wheel-drive version?

Yes, the cross-reference includes the 5L50E (RPO MV3 and M22) along with the 5L40E and 4L40E. Confirm the case and transfer case details on your unit before assembly.

What else should I replace during the reseal?

Replace the filter and pan gasket, inspect bushings and the direct/reverse housing, and replace any clutch packs that measure out of spec. Flush the cooler before the first fill.

Do I need a relearn after installing it?

Yes. Clear the old adaptive values with a scan tool and let the control module relearn shift pressures through a series of normal drive cycles.

• Transmission Slipping Diagnosis Guide
• Adaptive Relearn After a Valve Body or Rebuild
• ATF Color and Smell Diagnosis Chart
• How to Flush a Transmission Cooler After a Failure