Editing Vacuum gauge engine diagnosis

==Engine diagnosis using a vacuum gauge==
*[http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm Vacuum gauge chart]
*[http://www.secondchancegarage.com/public/186.cfm How to Use and Interpret a Vacuum Gauge]
*[http://www.gregsengine.com/using-a-vacuum-gauge.html Engine Testing with a Vacuum Gauge]
*[http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.htm Dealing With Engine Vacuum] from TheRangerStation.com 

==Diagnostic vacuum readings==
===Chart===
[[File:Vacuum Chart Web2.jpg|600px]]

===Table===
<table>
    <tr bgcolor="white"> 
      <td colspan="3">&nbsp;</td>
    </tr>
    <tr bgcolor="yellow"> 
      <th width="26%">ENGINE RPM</th>
      <th width="28%">GAUGE READING</th>
      <th width="46%">ENGINE CONDITION</th>
    </tr>
    <tr bgcolor="white"> 
      <td width="26%">Smooth and steady idle<br> (800 to 1200 RPM)</td>
      <td width="28%">Between 17 to 21 inches</td>
      <td width="46%">Engine is in good condition, but perform next test to be sure.</td>
    </tr><tr bgcolor="lightgrey"> 
      <td width="26%">Open and close throttle quickly</td>
      <td width="28%">Jumps from 2 to about 25 inches</td>
      <td width="46%">Engine is in good condition.</td>
    </tr><tr bgcolor="white"> 
      <td width="26%">Smooth and steady idle</td>
      <td width="28%">Steady, but lower than normal reading</td>
      <td width="46%">Worn rings, but perform next test to be sure.</td>
    </tr><tr bgcolor="lightgrey"> 
      <td width="26%">Open and close throttle quickly</td>
      <td width="28%">Jumps from 0 to 22 inches</td>
      <td width="46%">Confirms worn rings.</td>
    </tr><tr bgcolor="white"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Intermittent dropping back 3 to 5 inches and returns to normal</td>
      <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>
    </tr><tr bgcolor="lightgrey"> 
      <td width="26%">Steady 3000 RPM</td>
      <td width="28%">Pointer fluctuates rapidly, increasing engine speed causes more pointer swing</td>
      <td width="46%">Weak valve springs.</td>
    </tr><tr bgcolor="white"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Fast fluctuation between 14 to 19 inches</td>
      <td width="46%">Worn intake valve stem guides. Excessive pointer vibration at all speeds indicates a leaky head gasket.</td>
    </tr><tr bgcolor="lightgrey"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Constant drop</td>
      <td width="46%">Burnt valve or insufficient tappet clearance holding valve partly open or a spark plug occasionally misfiring.</td>
    </tr><tr bgcolor="white"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Steady 8 to 14 inches</td>
      <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>
    </tr><tr bgcolor="lightgrey"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Steady 14 to 16 inches</td>
      <td width="46%">Incorrect ignition timing.</td>
    </tr><tr bgcolor="white"> 
      <td width="26%">Steady idle</td>
      <td width="28%">Drifting from 14 to 16 inches</td>
      <td width="46%">Plug gaps too close or points not adjusted correctly. Damaged plug or 
       coil wire</td>
</table>
<br><br>

==Resources==
'''[[Finding vacuum leaks]]'''

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[[Category:Troubleshooting]]
[[Category:Carburetors]]
[[Category:Engine]]
[[Category:Good articles]]