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Tech Tip Corner
Blowing Bubbles![]()
Here's a quick, easy, and inexpensive way to find an external vacuum leak:
- First, use a mechanic's stethoscope (just the hose, no steel probe) to try to localize the leak with the engine running. Check the carb base, body, hoses, or what have you.
- Turn the engine off, then use a small spray bottle of extra-soapy water to spray the suspected area with a moderate amount of water.
- Next, find a manifold vacuum port (the brake servo booster hose for example) to apply a small amount of shop air. Apply just enough air pressure to get the soap to bubble. We don't want to ruin any check valves or anything.
- Seal the carburetor throat(s), then watch for the bubbles. You'll find the precise location of your leak.
Todd Schmeltz
Integrity Automotive
Oak Harbor, Washington
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