Seal and Gasket Diagnostics – Lexus RX (2017)

A Lexus RX 2017 arrived at our service due to an oil leak in the area between the engine and transmission. With this type of issue, the correct approach is not to replace the first suspicious part immediately. The source of the leak must first be identified precisely, along with the extent of the problem and which seal or gasket actually needs replacement.

On this vehicle, the leak appeared in the area where the engine meets the transmission. The customer had noticed oily marks under the car and wanted to know whether it was a minor leak or a repair that should not be postponed. That is why we started with disassembly and detailed diagnostics.

Disassembly and First Inspection

The first step was to remove the necessary components to access the area where the oil leak could be coming from. Without disassembly, it would not be possible to determine precisely whether the issue was on the engine side, the transmission side, or in the related seals.

For the Lexus RX 2017, we carried out:

• disassembly of the required parts to access the leak area
• first visual inspection of the engine and transmission
• inspection of oily marks around the engine-transmission joint
• checking individual seals and gaskets
• assessment of the leak extent
• preparation of the recommended repair plan

The goal was to identify the exact source of the leak and avoid replacing parts without a clear reason.

Inspection of Seals and Related Gaskets

The diagnostics showed that the issue was related to the rear crankshaft seal and the connected seal toward the transmission. We also checked the torque converter seal, because when oil leaks in this area, it is important to inspect all nearby components.

The inspection included:

• checking the rear crankshaft seal
• inspecting the related seal toward the transmission
• checking the torque converter seal
• inspection of surrounding sealing surfaces
• topping up operating fluids where required
• checking the oil level before the next engine start

Before starting the engine again, the oil level had to be checked first, fluids topped up if needed, and only then could the vehicle be started. With an oil leak, this step is essential, as starting the engine with insufficient oil can cause further damage.

Diagnostic Result

The result of the diagnostics was a clear identification of the issue. The rear crankshaft seal needed to be prepared for replacement, and we also recommended replacing the related seal toward the transmission. After completing the work, the process also included topping up fluids and performing wheel alignment.

This type of service is not just about finding an oily spot. The key is to understand where the oil is actually leaking from, what must be replaced now, and what makes sense to do at the same time so the same area does not need to be disassembled again.

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Frequently Asked Questions

1. How can you recognize an oil leak from a seal?

Common signs include oily marks under the car, oil smell, dirty engine or transmission components, and a gradual drop in oil level. The exact source must be confirmed by diagnostics.

2. Why is the torque converter seal also checked?

Because it is located in the same general area between the engine and transmission. If oil is leaking there, several related seals should be inspected at once.

3. Why must the oil level be checked before starting the engine?

If the car has been losing oil, the level may be low. Starting the engine without enough oil can cause serious damage to the engine or related components.

Conclusion

The Lexus RX 2017 underwent seal and gasket diagnostics due to an oil leak in the engine and transmission area. After disassembly, we identified the main source of the issue, checked the rear crankshaft seal, related transmission-side seal, and torque converter seal, and prepared the vehicle for the correct repair. The result is a clear repair plan without unnecessary blind replacement.