A TH350 transmission, with a stock pan, typically takes 4 quarts of transmission fluid.
The Turbo-Hydramatic 350 (TH350) is a robust and widely used three-speed automatic transmission by General Motors, commonly found in a variety of cars and trucks from the late 1960s through the early 1980s. Understanding its fluid capacity is crucial for proper maintenance and ensuring its longevity.
TH350 Fluid Capacity Overview
The fluid capacity specifies the amount of transmission fluid required to fill the system when performing a fluid change, typically involving draining the pan and replacing the filter.
Transmission Fluid Capacities (with Stock Pan)
To provide a clear understanding, here's a quick reference for common GM automatic transmissions with their stock pan capacities:
| Transmission (with Stock Pan) | Number of Quarts |
|---|---|
| GM TH350 | 4 |
| GM TH400 | 6 |
| GM Powerglide | 4 |
Please note: These capacities refer to the fluid held within the transmission pan and valve body, which is what typically drains during a standard fluid and filter change.
Factors Influencing Total Fluid Capacity
While the stock pan capacity is 4 quarts for a TH350, the total amount of fluid needed for a complete fill (e.g., after a rebuild or when replacing the torque converter and external cooler lines) will be significantly higher.
Several factors can influence the overall fluid volume a TH350 system requires:
- Torque Converter: The torque converter, a vital component that transfers power from the engine to the transmission, holds a substantial amount of fluid. A dry torque converter can add several quarts to the total capacity.
- Aftermarket Transmission Pans: Many enthusiasts and builders opt for aftermarket transmission pans that are deeper than stock. These larger pans increase fluid capacity, which can help with cooling and extend fluid life, but also mean you'll need more fluid for a fill.
- External Coolers and Lines: If your vehicle utilizes an auxiliary transmission cooler or long cooler lines, these components will also hold fluid, adding to the total system capacity.
When performing a complete fluid replacement, such as during a transmission rebuild or installation of a new unit, it's not uncommon for a TH350 system to require 8 to 10 quarts or more of fluid to fill the transmission, converter, and cooler lines.
Recommended Fluid Type
For TH350 transmissions, DEXRON III/MERCON equivalent fluids are typically recommended. Newer specifications like DEXRON VI are often backward compatible and can provide enhanced performance and longevity. Always check your vehicle's specific recommendations or consult with a transmission specialist if unsure.
Checking and Maintaining Fluid Levels
Accurately checking and maintaining your TH350's fluid level is paramount for its proper operation and longevity.
Here are some practical insights:
- Warm Engine: Always check the transmission fluid level with the engine warm and running, ideally after driving for a few minutes to circulate the fluid.
- Level Surface: Ensure the vehicle is parked on a flat, level surface to get an accurate reading.
- Gear Selector Position: With the engine running and warm, cycle the gear selector through all positions (P, R, N, D, 2, 1) before returning it to Park (P) or Neutral (N) as specified by your vehicle's manual.
- Dipstick Reading: Withdraw the dipstick, wipe it clean, reinsert it fully, and then pull it out again to check the level. The fluid should be between the "full" marks.
- Gradual Addition: Add fluid in small increments (e.g., half a quart at a time), rechecking the level each time, to avoid overfilling. Overfilling can cause foaming and damage.
Regularly inspecting your transmission fluid for proper level and condition (color, smell) can help detect potential issues early and prevent costly repairs. For more technical information on transmission fluid capacities, you can refer to resources like ATI Performance.
