Balance shaft is an eccentric weighted shaft that offsets vibrations in engine designs that are not inherently balanced.
Toyota also began to use balance shafts in their 3RZ-FE engines in the mid 90s. Among other engines that use balance shaft are: Toyota 2.4L (2AZ-FE), 2.5L (2AR-FE), 2.7L (1AR-FE)
Balance shaft need to be replaced every (recommended) 100,000 KM or whenever the balance shaft problem symptoms detected. My personal advice, please be extra careful and start to monitor for the symptoms when you have reached 80,000 KM (please consider the car milage from Japan before it get reset in Malaysia)
Some of the symptoms of early deterioration of the part include:
- Rough idling
- Intensified rattling noises with increased acceleration or cold start
- Rough running including engine stalling and engine misfiring
- Illumination of the check engine light.
You may refer the the following video to help you to understand the “rough” noise
The cost to replace balance shaft is around RM850-RM1200 including labour. You might be charge slightly more depending on the type/brand of engine oil to be used.
Toyota part number for ACR50 and ANH20 are: 13601-28021 & 13602-28020 (Also available online sold in Shopee by my trusted seller: HERE)