Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1979 BMW 633CSi Automatic TransFACTORY OEM SERVICE PROCEDURE
Electromagnetic Switching Valve
NOTE:
633CSi and 733i models are equipped with two or three electromagnetic switching valves. The switching valve for the transmission controlled spark system can be identified by the Black cap.
- With ignition switch in the "ON" position and engine stopped, shift transmission into 4th gear. Disconnect switching valve-to-distributor advance unit vacuum hose.
- Disconnect remaining switch valve vacuum hose at thermo valve (320i) or at throttle housing (633CSi and 733i) and blow air into hose.
- Switching valve is okay if air passes through it with transmission in 4th gear but is blocked when transmission is shifted out of 4th gear. If not, switching valve is defective and should be replaced.
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:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • 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 QuoteNo obligation. See pricing before you book.