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techtalk:ref:oil07 [2019/11/14 16:26]
hippysmack [Micron Ratings]
techtalk:ref:oil07 [2020/09/09 02:55] (current)
hippysmack [Anti-Drainback Valve]
Line 153: Line 153:
     * Some filter designs incorporate a combination anti-drain and relief valve with an integrated unit construction.     * Some filter designs incorporate a combination anti-drain and relief valve with an integrated unit construction.
  
-|On some engines the filter is mounted in a position which allows the oil in the filter to drain back to the crankcase when the engine is stopped ((Fram PDF Oil Pressure Warning Light Problems https://​www.fram.com/​support/​tech-documents/​consumer-documents/​))This would be the case for the filter mounting shown in Figure 2 where the filter is horizontal and is above the level of the oil in the crankcase. Since a filter holds up to a quart of oil, it takes about 5 seconds for the pump to fill the filter after the engine has been started ​during ​which time the warning light will remain on. To prevent the engine from operating without oil pressure for this period of time after startup, ​the filters designed for these special mounting positions contain an anti-drain back valve. This valve is usually in the form of a rubber gasket which allows the free flowof ​oil through the filter in the normal direction, but when the engine is shut down it prevents the oil in the filter from draining back to the crankcase. If the warning light remains on for longer periods after the filter ​has been on the car for some time, replacing the filter ​is recommendedUnder some conditions ​the warning light may flicker ​when the engine is running. This usually happens when the car is going around ​corner ​or is on a relatively steep hillIf flickering occurs under these conditionsit is because the oil level is low and the pump strainer is no longer fully submerged ​in the oil. The oil level should be immediately brought up to normalIn summary, the oil pressure warning light provides vital information ​to the driverIf the light remains on or even flickers when the engine is running, it should be shut off immediately ​and the cause investigated.+On some car engines the filter is mounted in a position which allows the oil in the filter to drain back to the crankcase when the engine is stopped((Fram PDF Oil Pressure Warning Light Problems https://​www.fram.com/​support/​tech-documents/​consumer-documents/​)) ​\\  
 +This would be the case where the filter is horizontal and is above the level of the oil in the crankcase. ​\\  
 +Since a filter holds up to a quart of oil, it takes about 5 seconds for the pump to fill the filter after the engine has been started. \\  
 +During ​which time the warning light will remain on. \\  
 + 
 +To prevent the engine from operating without oil pressure for this period of time after startup, ​\\  
 +Some filters ​are designed for these special mounting positions ​to contain an anti-drain back valve. ​\\ 
 +This valve is usually in the form of a rubber gasket which allows the free flow of oil through the filter in the normal direction. \\ 
 +But when the engine is shut downit prevents the oil in the filter from draining back to the crankcase ​(oil pump in the case of Sportsters). \\ 
 + 
 +There is no need to install a filter ​with an anti-drainback valve on a Sportster. \\ 
 +The oil tank sits higher than the oil filter ​housingSo if any oil could drain back, oil can't run uphill by itself. \\ 
 +Sportsters have an inherent problem with oil gravity draining into the engine ​when the engine is shut off and it sits for a while (sit-sumping)\\ 
 +This is due to either ​worn check valve or worn clearances in the oil pump\\ 
 +So, oil in a Sportster will be pushed against ​the filter at all times without a drainback valve in the filter. \\  
 +  
 + 
 +This is from a HD Parts and Accessories Bulletin (PAB-398) dated 11-1-1988. Low restriction ​oil filter (63806-83) has been obsoleted\\ 
 +It was originally offered as a low restriction filter to insure proper return of oil to the oil tank. \\ 
 +This filter did not have a drain-back valve (**which is not required in Harley-Davidson applications**) to reduce restriction\\ 
 +Recently, the drain-back valve was removed from oil filters 63796-77 (chrome) and 63805-80 (black) ​to reduce oil filter restriction\\ 
 +The part numbers were changed to 63796-77A ​and 63805-80A to reflect this change. \\ 
 +Either of these oil filters can be used in place of 63806-83\\
  
 ===== Relief (Bypass) Valve ===== ===== Relief (Bypass) Valve =====