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techtalk:ref:oil07 [2020/03/29 23:06] hippysmack [Anti-Drainback Valve] |
techtalk:ref:oil07 [2022/08/21 18:35] (current) hippysmack [Anti-Drainback Valve] |
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| But when the engine is shut down, it prevents the oil in the filter from draining back to the crankcase (oil pump in the case of Sportsters). \\ | But when the engine is shut down, it 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 housing. So 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 a 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. \\ | ||
| + | Oil will also be pushed against the filter at all times with a drainback valve in the filter. \\ | ||
| + | The only thing a drainback filter will do is add restriction / raise pressure on the hose feeding the oil filter. \\ | ||
| + | An anti-drainback valve will not stop or even slow "sit-sumping" as we know it with the engine shut down. \\ | ||
| + | When the ADV rubber flap closes in the filter, it just keeps oil that is in the non filtered side from coming back down the inlet hose to the filter. \\ | ||
| + | It does not stop oil from seeping or otherwise entering the inlet side of the filter (just from leaving /reversing out the inlet hose). \\ | ||
| + | Any oil that has made it thru the filter media is not affected by the rubber flap (not stopped from flowing or seeping out). \\ | ||
| + | With the filter on the feed side (86-up), gravity will push oil down the feed hose from tank, past the oil pump, past the ADV flap and into the filter. \\ | ||
| + | With filter on return side (85-down), the only oil that can get back to motor from filter is what is present between filter inlet (before ADV) and motor. \\ | ||
| + | The oil check ball / valve is suppose to stop any oil from leaving the filtered side from getting into the motor. \\ | ||
| + | The ADV has no relation to wetsumping on a Sportster. Oil drainback from the return side through the pump should be minimal at best. \\ | ||
| + | * On 1979-1985 Sportsters, the only thing an ADV will prevent is oil coming back down the return line from the tank to filter (only what's in that portion of hose on shutdown). \\ So what oil may be stored on shutdown between the filter and the tank isblocked from re-entering the motor back through the pump. \\ (whether a short section of hose or hosing and oil cooler content if applicable) \\ | ||
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| This is from a HD Parts and Accessories Bulletin (PAB-398) dated 11-1-1988. Low restriction oil filter (63806-83) has been obsoleted. \\ | 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. \\ | It was originally offered as a low restriction filter to insure proper return of oil to the oil tank. \\ | ||
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| The part numbers were changed to 63796-77A and 63805-80A to reflect this change. \\ | 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. \\ | Either of these oil filters can be used in place of 63806-83. \\ | ||
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| + | {{:techtalk:ref:oil:1979-1985_sportster_with_anti-drainback_valve_in_filter_by_hippysmack.png?direct&400|}} ((drawing by Hippysmack)) \\ | ||
| ===== Relief (Bypass) Valve ===== | ===== Relief (Bypass) Valve ===== | ||
