Buyer's Guide

The Large Drive Unit uses coolant flowing through the rotor shaft to cool the motor. Over time, the internal seal between the coolant path and the rotor deteriorates, allowing coolant to leak inside the drive unit. This internal leak causes flushing of grease from rotor bearings, corrosion of internal components, shorting of electronics in the inverter, and can ultimately lead to complete motor failure.

• Affects ALL P-series vehicles (P85, P85D, P90D, P100D) and ALL RWD models (2012-2020)
• Only non-performance dual motor (D) variants use a different motor without this issue
• The leak is entirely internal, you will not see external dripping
• The car can leak for months and thousands of miles before any MCU warnings appear
• Warning signs when it gets bad: reduced power, 'powertrain needs service' alerts, unusual noises
• Tesla acknowledged the design flaw and released 'Revision U' replacement motors in late 2023 that delete rotor coolant entirely

There is a DIY method to check whether your LDU has already started leaking. This involves inspecting the rotor speed sensor (encoder sensor) and should be done at least once a year on any LDU-equipped vehicle.

• Locate the rotor speed sensor (encoder sensor) on the drive unit
• Carefully remove the speed sensor from its mounting hole
• Visually inspect the sensor and inside the mounting hole for any signs of moisture, condensation, or blue-colored coolant
• Wipe the sensor with a white paper towel. If the grease shows any blue tint, coolant has leaked past the seal
• If you find blue coolant, a coolant delete should be done as soon as possible to prevent further damage
• If the sensor is dry and clean, the seal is still holding, but a preventive coolant delete is still recommended

A coolant delete permanently blocks coolant from entering the rotor shaft, eliminating the leak risk entirely. This replicates what Tesla themselves did with their 'Revision U' motors. There are two approaches, both are acceptable. Coolant continues to flow to the stator, inverter, and gearbox in either case.

• OPTION A, Delete Cap: A stainless steel or aluminum cap is pressed into the 55mm bore in the coolant manifold where the leaky seal sits, permanently blocking rotor coolant flow. The cap itself is inexpensive (~$40 from suppliers like Tesx.net, AmpRevolt, or Revolt Systems) but the LDU must be removed from the car to install it.
• OPTION B, Replacement Manifold: The entire coolant manifold is replaced with an aftermarket unit (such as from Tesx.net or QC Charge) that has no rotor coolant path. More parts cost but achieves the same result.
• Both options eliminate the risk of coolant entering the rotor
• Coolant continues flowing to the stator, inverter, and gearbox (only rotor coolant is deleted)
• This replicates Tesla's own Revision U fix released in late 2023
• Can be performed by many independent Tesla shops. Two that come highly recommended are Tesx.net in Armstrong, Iowa and Energized EV in Pomona, CA
• Cost: typically $1,200 to $2,500 including parts and labor. The parts are cheap but labor is significant since the LDU must be removed from the vehicle

A weep hole is a small hole drilled into the bottom of the LDU housing. The idea is that if coolant does leak from the seal, it drains out of the motor rather than pooling inside and damaging components. This is a less comprehensive fix than a coolant delete.

• Small hole drilled in the bottom of the LDU housing
• Allows any leaked coolant to drain out rather than accumulate inside the motor
• Does NOT prevent the leak, it just provides drainage
• Less ideal than a coolant delete because the leak still occurs and coolant is still lost over time
• Better than nothing as a stopgap, but coolant delete is the preferred permanent solution

The coolant delete is an internal modification. The delete cap sits inside the coolant manifold bore, so it is not easily visible from a casual external inspection. Here is how to confirm:

• Ask the seller directly if a coolant delete has been performed
• Request documentation or receipts from the shop that did the work
• Check service records for mentions of coolant delete, rotor manifold replacement, delete cap, or Revision U
• If a Tesla replacement motor was installed, check for a '-U' suffix in the drive unit part number, which indicates it is a Revision U motor with no rotor coolant
• Ask in Tesla owner communities. If the car has changed hands, previous owners or the shop may be able to confirm
• If no documentation exists, assume it has NOT been done and budget $1,200 to $2,500 for the work