What Causes Foam in Transmission Fluid?

[VanAlejandro]

Transmission fluid foaming is caused by either excessively high or low fluid levels. Below is a detailed explanation of the causes: Foaming due to high fluid level: When the fluid level is too high, planetary gears and other rotating components become partially submerged in the transmission fluid, causing agitation that leads to bubble formation. Foaming due to low fluid level: If the fluid level is too low, the oil pump may draw in air, mixing it with the fluid and creating bubbles. Hazards of bubbles in transmission fluid: When bubbles enter the hydraulic control system, they reduce hydraulic pressure, affecting normal transmission operation and potentially causing slippage. Additionally, bubbles can cause fluid expansion, leading to overflow through transmission vents and filler openings, which may result in incorrect diagnostics.