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| − | ==Engine diagnosis using a vacuum gauge==
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| − | *[http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm Vacuum gauge chart]
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| − | *[http://www.secondchancegarage.com/public/186.cfm How to Use and Interpret a Vacuum Gauge]
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| − | *[http://www.gregsengine.com/using-a-vacuum-gauge.html Engine Testing with a Vacuum Gauge]
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| − | *[http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.htm Dealing With Engine Vacuum] from TheRangerStation.com
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| − | ==Diagnostic vacuum readings==
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| − | ===Chart===
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| − | [[File:Vacuum Chart Web2.jpg|600px]]
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| − |
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| − | ===Table===
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| − | <table>
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| − | <tr bgcolor="white">
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| − | <td colspan="3"> </td>
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| − | </tr>
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| − | <tr bgcolor="yellow">
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| − | <th width="26%">ENGINE RPM</th>
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| − | <th width="28%">GAUGE READING</th>
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| − | <th width="46%">ENGINE CONDITION</th>
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| − | </tr>
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| − | <tr bgcolor="white">
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| − | <td width="26%">Smooth and steady idle<br> (800 to 1200 RPM)</td>
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| − | <td width="28%">Between 17 to 21 inches</td>
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| − | <td width="46%">Engine is in good condition, but perform next test to be sure.</td>
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| − | </tr><tr bgcolor="lightgrey">
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| − | <td width="26%">Open and close throttle quickly</td>
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| − | <td width="28%">Jumps from 2 to about 25 inches</td>
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| − | <td width="46%">Engine is in good condition.</td>
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| − | </tr><tr bgcolor="white">
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| − | <td width="26%">Smooth and steady idle</td>
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| − | <td width="28%">Steady, but lower than normal reading</td>
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| − | <td width="46%">Worn rings, but perform next test to be sure.</td>
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| − | </tr><tr bgcolor="lightgrey">
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| − | <td width="26%">Open and close throttle quickly</td>
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| − | <td width="28%">Jumps from 0 to 22 inches</td>
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| − | <td width="46%">Confirms worn rings.</td>
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| − | </tr><tr bgcolor="white">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Intermittent dropping back 3 to 5 inches and returns to normal</td>
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| − | <td width="46%">Sticky valves. If injection of penetrating oil into intake manifold temporarily stops pointer from dropping back, it's certain the valves are sticking.</td>
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| − | </tr><tr bgcolor="lightgrey">
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| − | <td width="26%">Steady 3000 RPM</td>
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| − | <td width="28%">Pointer fluctuates rapidly, increasing engine speed causes more pointer swing</td>
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| − | <td width="46%">Weak valve springs.</td>
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| − | </tr><tr bgcolor="white">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Fast fluctuation between 14 to 19 inches</td>
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| − | <td width="46%">Worn intake valve stem guides. Excessive pointer vibration at all speeds indicates a leaky head gasket.</td>
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| − | </tr><tr bgcolor="lightgrey">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Constant drop</td>
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| − | <td width="46%">Burnt valve or insufficient tappet clearance holding valve partly open or a spark plug occasionally misfiring.</td>
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| − | </tr><tr bgcolor="white">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Steady 8 to 14 inches</td>
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| − | <td width="46%">Incorrect valve timing. It must also be remembered that vacuum leaks and/or poor compression can result in a low vacuum reading.</td>
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| − | </tr><tr bgcolor="lightgrey">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Steady 14 to 16 inches</td>
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| − | <td width="46%">Incorrect ignition timing.</td>
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| − | </tr><tr bgcolor="white">
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| − | <td width="26%">Steady idle</td>
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| − | <td width="28%">Drifting from 14 to 16 inches</td>
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| − | <td width="46%">Plug gaps too close or points not adjusted correctly. Damaged plug or
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| − | coil wire</td>
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| − | </table>
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| − | <br><br>
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| − |
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| − | ==Resources==
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| − | '''[[Finding vacuum leaks]]'''
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| − | <br><br>
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| − |
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| − | [[Category:Troubleshooting]]
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| − | [[Category:Engine]]
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| − | [[Category:Good articles]]
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