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techtalk:ref:engmech04a [2019/08/05 04:50] hippysmack [Dissecting the Hayden KVP38 Crankcase Breather Valve] |
techtalk:ref:engmech04a [2020/09/24 01:14] hippysmack [Dissecting the Hayden KVP38 Crankcase Breather Valve] |
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**The gear driven breather's last year was 1978. \\ | **The gear driven breather's last year was 1978. \\ | ||
- | They left out the '79 style internal reed valve. \\ | + | They left out the '79 style internal reed valve and the fact that Sportsters lost the timed breather in '77. \\ |
- | They are representing ironhead technology up to 1992. \\ | + | They are representing ironhead technology up to 1992 (not true for Sportsters). \\ |
They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\ | They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\ | ||
Some points of interest:** \\ | Some points of interest:** \\ | ||
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* **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\ | * **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\ | ||
* **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)** | * **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)** | ||
- | * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** | + | * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** \\ This is true. |
- | * **It also says the OEM umbrella is normally closed. But it isn't sealed and we do know they do let air back into the crankcase.** | + | * **It also says the OEM umbrella is normally closed**. \\ But it isn't sealed all the time (transients) and we do know they do let a slight amount of air back into the crankcase. \\ This helps to equalize mean pressure somewhat. |
* **According to the patent information, the drain hole in the breather valve system has a dual purpose.** | * **According to the patent information, the drain hole in the breather valve system has a dual purpose.** | ||
- **It drains oil that gets past the umbrella.** | - **It drains oil that gets past the umbrella.** |