R154 Transmission Fluid Fill - Correct Fill Hole Location and Procedure

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Problem

Owner could not fill R154 transmission with fluid after draining. Attempted to pour fluid through the top shifter hole but fluid would not drain down after ~70% of one quart. Was also unsure which plug was the actual fill hole, as someone had replaced the original 24mm hex plug with a torx/star-shaped plug.

Transmission fluid would not drain down when poured through the top shifter holeFluid pooled and sat at the top of the shifter openingConfusion over fill hole location due to non-standard replacement plugTorx/star plug in fill hole did not fit standard 8mm or 10mm torx sizes

Root Cause

The owner was trying to fill through the shifter hole from the top, which does not allow adequate airflow for the fluid to drain down. The correct fill hole is the side plug on the transmission case (adjacent to the slave cylinder), but a previous owner had replaced the factory 24mm hex bolt with a non-standard torx/star plug, causing confusion about which hole to use and difficulty removing it.

Confidence

Moderate confidence — Multiple community members agreed on this solution

View Original Thread →Posted May 2020 on SupraForums.com