Differences

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--- techtalk:ih:oil03c [2018/12/12 02:51]
hippysmack [77-85 Oil Pump Damage Pics]
+++ techtalk:ih:oil03c [2018/12/19 16:57]
hippysmack
@@ Line 2: / Line 2: @@
 ====== IH: Oiling & Lubrication - Sub-03A ======
 ====== 77-85 Oil Pump Damage Pics ======
-|{{:techtalk:ih:oil:83_oil_pump_by_sc72.jpg?direct&300|}}|{{:techtalk:ih:oil:77_oil_pump_gearshaft_pin_broke_by_77_iron.jpg?direct&500|}}|
+====== Cracks in Housing or Cover ======
-|  Oil pump from an 83 model ((photo by sc72 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717592&page=15))  |  Gearshaft pin broke off into this 77 model ((photo by 77 iron of the XLFORUM http://xlforum.net/forums/showthread.php?t=1831941&page=2))  |
+====== Scratches on Gerotors or Mating Surfaces ======
   * Many used oil pumps have scratches on both the gerotors and pump surfaces that the gerotors ride on.
@@ Line 17: / Line 18: @@
 |{{:techtalk:ih:oil:77-85_oil_pump_cover_7_by_hippysmack.jpg?direct&500|}}|{{:techtalk:ih:oil:77-85_oil_pump_cover_8_by_hippysmack.jpg?direct&500|}}|
-  * The inner gerotor spins in this same position as it is mounted to the gearshaft.
+  * In theory, no particles of any size should be able to spin around to the small pad due to the pressure generated by the spring washer and the gerotor spacing there.
-  * The outer gerotor spins by way of the gears inside the cover but also in the same position to the inner gear as below in operation.
+  * Also, any debris picked up from the source side cavity should drop down into the feed side cavity and out of the pump.
-  * The gearshaft is off center to the outside gerotors on both feed and return.
+  * The side toward the motor is where oil is transferred to and from the pump.
-  * There are 8 teeth on the inner and 9 on the outer gerotor in each set.
+  * The inner and outer gears come together on the other side (right side).
-  * This allows for the cavity between the inner and outer gears for oil transfer.
+  * This spacing relationship doesn't change between the motor side or the outside of the pump due to the offset gearshaft.
+  * But in reality, debris gets caught in or between the gears and gets dragged over the aluminum flats.
+    * Some then find their way under the gerotors while the spring washer flexes from the stress.
+    * The debris spins around under the gerotors and wears scratches in the flats (pads) or worse.
+|{{:techtalk:ih:oil:77-85_oil_pump_cover_9a_by_hippysmack.jpg?direct&500|}}|{{:techtalk:ih:oil:77-85_oil_pump_cover_10a_by_hippysmack.jpg?direct&500|}}|
+|  Gerotor rotation ((photos by Hippysmack http://xlforum.net/forums/showthread.php?t=2071153&page=6))  ||
+|{{:techtalk:ih:oil:83_oil_pump_by_sc72.jpg?direct&300|}}|{{:techtalk:ih:oil:77_oil_pump_gearshaft_pin_broke_by_77_iron.jpg?direct&500|}}|
+|  Oil pump from an 83 model ((photo by sc72 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717592&page=15))  |  Gearshaft pin broke off into this 77 model ((photo by 77 iron of the XLFORUM http://xlforum.net/forums/showthread.php?t=1831941&page=2))  |
- In theory, no particles of any size should be able to spin around to the small pad due to the pressure generated by the spring washer and the gerotor spacing there.
+  * There should be some reduced pressure because of the scratches.
- The side toward the motor is where oil is transferred to and from the pump.
+  * Pressure generated to the output cavity can squirt back to the input side through these scratches.
- The inner and outer gears come together on the other side (right side).
+  * How much pressure loss would depend on the width, depth, length of the scratches and oil viscosity.
- This spacing relationship doesn't change between the motor side or the outside of the pump due to the offset gearshaft.
+  * To make the pump inoperative or not make pressure (from the scratches alone);
- Left side of 1st pic below goes toward the motor.
+    * The scratches would have to be proportional to the relative volume of all four gerotor reservoirs combined.
-|{{:techtalk:ih:oil:77-85_oil_pump_cover_9_by_hippysmack.jpg?direct&500|}}|{{:techtalk:ih:oil:77-85_oil_pump_cover_10_by_hippysmack.jpg?direct&500|}}|
+    * Then, the check valve would have to accept less pressure flow than the backpressure from the pump.
+  * The gerotor surface in the cover would have to be eat up pretty bad to make the pump completely ineffective.
+  * The pump would have less pressure loss with multi-weight or straight weight oil when cold than hot.
+  * They'll both flow faster when hot.

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