This document addresses an intermittent, high-pitched squealing noise emanating from the engine bay of Toyota Prado vehicles, primarily the 2.8L diesel models, although a 3.0L model also reports the same issue. The noise typically occurs at speeds around 80 km/h and at approximately 1500 rpm, both under load and while coasting.
Problem
The primary symptom is a loud, high-pitched squealing noise described as similar to metal-on-metal contact or a high-pitched ringing. The noise is intermittent and difficult to replicate consistently, making diagnosis challenging. The noise may originate from the front of the vehicle and under the glovebox.
Possible Causes and Solutions
- DPF Regeneration: Some suggest the noise may be related to the Diesel Particulate Filter (DPF) regeneration process. Giving the vehicle “some gas” over a few kilometres may resolve this.
- Fan Belt Slippage: Check the fan belt for wear or looseness.
- Brakes: Although initially suspected, a rock or debris caught in the brakes is unlikely to be the cause if the noise persists under various driving conditions.
- Ringing Noise from Beneath Glovebox: Check the ECU. It is unknown if this is related.
SOLUTION: There is no confirmed single solution to the problem. Due to the intermittent nature of the sound, it is difficult to diagnose.
Additional Notes
- The issue has been reported on vehicles both with and without DPFs, suggesting the DPF is not always the cause.
- The noise may be more apparent when the engine is warm, but this is not consistently reported.
- Some owners have experienced the noise disappearing after a period of time (e.g., 1000km) without intervention.
- Record videos of the noise to demonstrate the issue to technicians, even if they cannot replicate it during a test drive.
This technical summary was auto-generated based on recovered archives. Do not rely on its factual accuracy. Refer to the original thread. Source: View Original Conversation
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