1972 Mazda R100 Automatic TransFACTORY OEM SERVICE PROCEDURE

Coasting Valve

With vacuum gauge attached in tube from air control valve to coasting valve, start engine and check that vacuum is more than 15.7 in. (400 mm) Hg. when engine speed is 800 RPM. Raise speed to about 2500 RPM and close throttle suddenly. Vacuum reading at this time should be 0-1.18 in. (0-30 mm) Hg. When engine speed decreases to 1100-1300 RPM, the reading should rise to more than 15.7 in. (400 mm) Hg.

Fig 1: Testing Coasting Valve
G09355121Courtesy of MAZDA MOTORS CORP.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.