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Vacuum on an R107 runs locks, climate flaps, transmission modulator behavior, brake booster assist, and other year-dependent consumers. Leaks create limp modes that look like “electrical gremlins.”
Related: climate, transmission.
Symptoms and consumers
Weak locks, wrong vents, harsh/soft shifts, hard brake pedal, odd idle/shutoff behavior depending on year. Map which systems failed — that narrows lines and pods.
Smoke test and diagrams
Smoke or careful listening finds cracked tees and perished hoses. Use year-correct vacuum routing references; the illustration here is conceptual — do not treat it as a photocopy of OEM art.
Common mistakes
Skipping cold and hot tests, trusting verbal history without invoices, replacing parts before measuring, and ignoring rust while chasing mechanical gremlins. Photos from another market or year are not a parts catalog.
When to stop DIY
Stop when you lack the gauge, puller, or safe support the job needs — or when the first repair did not change the symptom. Pay for diagnosis with someone who sees R107s regularly.
Practical takeaway
Replace brittle plastic tees in sets when they crumble in your fingers.
Shop notes and paperwork
Keep invoices, pressure readings, part numbers, and dated photos of the area before and after work. The next owner — or future you — will ask what was actually done. Verbal “we took care of it” evaporates at sale time.
Safety and scope
Use jack stands on solid ground, relieve fuel/coolant pressure before opening systems, and disconnect the battery when the procedure calls for it. If a step needs a specialty tool you do not own, rent it or hire it — improvising with the wrong lever is how fasteners and fingers break.
Verify against the factory manual for your engine and chassis. No invented personal car details here — use your plates, invoices, and measured symptoms.
Shop notes and paperwork
Safety and scope
If this topic intersects fuel, rust, or safety systems, fix the safety and leak paths before cosmetic or convenience items. That order saves money twice.
