Tesla Model S LDU Coolant Leak: Risks, Affected Models, and Solutions

may 28,2025,By lan

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1. What is Model S LDU Coolant Leak?

   The Large Drive Unit (LDU) in early Tesla Model S and Model X vehicles has a known issue. The problem is internal coolant leakage.

   This happens when the rotor seal fails. Coolant, which contains flammable glycol, can enter the motor.

Key risks include:

- Corrosion of internal parts

- Short circuits in the inverter

- Bearing damage

- Loss of high voltage isolation

- In severe cases, rotor seizure or even battery fire risk

Why is this dangerous?

   Coolant can flush out bearing grease. It can cause rust and copper wire corrosion. If it reaches the inverter, it may cause electrical shorts.

   If coolant leaks into the battery, it can leave flammable residue. This increases the risk of thermal runaway and fire.

   Expert sources and user reports confirm that this is a systemic flaw in the LDU design.

How to check for Drive-Unit coolant leakage on your Tesla Model S ?

2. Which Models and Years Are Affected?

Not all Teslas have this problem. The issue mainly affects:

Model Years Notes
Model S 2012-2020 RWD & Performance (LDU)
Model X 2015-2020 Performance RWD (LDU)
Model S/X 70D, 75D, 85D, 90D, 100D Not affected (Small Drive Unit)

Important details:

- The problem started in 2012 with the first Model S.

- Model X uses the same LDU and is also affected.

- Non-Performance dual motor models ("D" cars with small drive units) are not affected.

- Model 3 uses a different cooling system and is not affected.

Regulatory attention:

- In 2020, the NHTSA began investigating Tesla for possible defects in the cooling system.

- Internal emails show the issue was present from 2012 to 2016.

3. What Are the Solutions for LDU Coolant Leak?

There are several ways to address this issue. Each has pros and cons.

1. Tesla Official Solution: U Version Drive Unit

- In 2023, Tesla released an improved LDU (part number with "-U" suffix).

- This version uses a seal manifold delete. It blocks coolant from entering the rotor.

- Stator, gearbox, and inverter cooling are still active.

- Cost: About $6,000 (new), $5,200 (remanufactured).

2. Third-Party Coolant Delete Kits

- QC Charge offers a kit for $599.

- It blocks only the rotor coolant. Gearbox oil cooling is preserved.

- Made from anodized aluminum for corrosion resistance.

- Low-cost options are available on eBay and other sites.

3. Drilling Weep Holes

- Some owners drill holes at the bottom of the LDU.

This allows leaked coolant to drain out.

- Warning: This method is risky. It can damage electronics if not done carefully.

4. Regular Inspection and Maintenance

- Check the speed sensor regularly.

- If you see blue coolant or rust, take action immediately.

Coolant Delete: The Most Popular and Permanent Solution

   The coolant delete modification has become the most popular and permanent solution among Tesla owners and independent repair shops. 

   This method physically blocks coolant from entering the rotor shaft, completely eliminating the risk of internal leaks.

Key points about the coolant delete

- The modification can be done using a stainless steel or aluminum plug/cap pressed into the coolant manifold, or by installing a third-party manifold.

- Some kits, like those from QC Charge or AmpRevolt, preserve coolant flow to the gearbox and inverter, closely replicating Tesla's official "Revision U" solution.

- DIY kits are available for as low as $40-50, while premium CNC manifolds can cost several hundred dollars.

- The process may require removing the LDU from the car, but some new kits allow for in-situ installation without full disassembly.

- Sealant (such as Permatex 64000) is recommended to ensure a leak-proof fit.

- This solution is suitable for all 2012-2020 Model S/X RWD and Performance models with the LDU.

- Warning: Performing this modification will void any remaining Tesla warranty on the drive unit.

Why is coolant delete so effective?

   It directly addresses the root cause: the flawed rotor seal.

   Once installed, there is no path for coolant to enter the rotor, so the risk of catastrophic failure is eliminated.

   The rest of the cooling system (stator, inverter, gearbox) remains functional.

Key Considerations and Controversies

- Warranty Impact: DIY modifications may void your warranty.

- Cooling Efficiency: Removing rotor cooling can increase bearing temperature. Ceramic bearings can handle higher heat.

- Risk Balance: Most users agree that coolant leaks are more dangerous than rotor overheating.

- All LDU units need a fix to prevent major failures.
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