Guide hub
Common problems
The practical way to troubleshoot R107 electrical problems: where to find wiring diagrams, how to read them, ground points, fuses, tools and the most common failures.
Common problems
How to find the cause of an R107 shimmy or vibration by speed band: wheels and tires, brakes, driveline or engine mounts.
Common problems
Why an R107 brake pedal sinks to the floor, how to tell a master cylinder fault from a leak or air, and how to fix it.
Common problems
How to test an R107 brake booster and its check valve, how vacuum leaks affect braking, and when to replace the booster or master cylinder.
Common problems
How the R107's heater valve works, why it fails, how to tell if it is stuck open or closed, and whether to rebuild or replace it.
Common problems
How to tell whether a high or low temperature gauge reading on an R107 is real, how to test the sender, and what normal looks like.
Common problems
When the R107's auxiliary electric fan should run, how its temperature switch, relay and fuse work, and how to test it.
Common problems
What the fan clutch does on an R107, the symptoms of a failing clutch, and simple cold and hot tests to check it.
Common problems
Normal charging voltage on an R107, how to test the alternator and regulator, and when to repair or replace it.
Common problems
Where the R107 starter is, how to diagnose click and no-click problems, heat soak, and whether to rebuild or replace it.
A little transparency
Guides are general owner notes from Arthur's R107 experience, not a substitute for a qualified mechanic or a pre-purchase inspection on your car. Always confirm part numbers and fitment for your chassis before you buy.
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