Editing Vacuum gauge engine diagnosis
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==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"> </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]]''' <br><br> [[Category:Troubleshooting]] [[Category:Engine]] [[Category:Good articles]]
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