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techtalk:evo:engmech07 [2019/11/14 04:40] hippysmack [Crankcase Ventilation] |
techtalk:evo:engmech07 [2020/08/08 23:21] hippysmack [2004-Present Engine Breathing] |
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| ====== 1991-2003 Engine Breathing ====== | ====== 1991-2003 Engine Breathing ====== | ||
| + | **An important note**: \\ | ||
| + | Factory engine breather valves on all Evo Sportsters are inside the engine. \\ | ||
| + | The lines / hoses that leave the engine and any apparatus to route the air to different places are part of the venting system. \\ | ||
| + | Many aftermarket manufacturers advertise that they are selling "Engine Breathers when they are actually only selling the vent line / tube assemblies. \\ | ||
| + | |||
| * In 1991, along with the 5-speed transmission, the MoCo moved the crankcase breathing from the cam box cover outlet to breather bolts in the heads. \\ Previously, these bolts were just used to mount the carb and air cleaner to the heads. | * In 1991, along with the 5-speed transmission, the MoCo moved the crankcase breathing from the cam box cover outlet to breather bolts in the heads. \\ Previously, these bolts were just used to mount the carb and air cleaner to the heads. | ||
| * The new breather system uses one-way umbrella valves (AKA Foo Foo Valves) in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) | * The new breather system uses one-way umbrella valves (AKA Foo Foo Valves) in the rocker boxes. \\ These exit crankcase vapors through vents in the top of the cylinder head into the carb mouth to be burnt. ((FoxsterUK of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=wet+sumping)) | ||
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| ====== 2004-Present Engine Breathing ====== | ====== 2004-Present Engine Breathing ====== | ||
| + | **An important note**: \\ | ||
| + | Factory engine breather valves on all Evo Sportsters are inside the engine. \\ | ||
| + | The lines / hoses that leave the engine and any apparatus to route the air to different places are part of the venting system. \\ | ||
| + | Many aftermarket manufacturers advertise that they are selling "Engine Breathers when they are actually only selling the vent line / tube assemblies. \\ | ||
| + | |||
| * In 2004 the MoCo made some changes to the umbrella valve configuration. \\ The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen. \\ Each 'breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\ The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape. | * In 2004 the MoCo made some changes to the umbrella valve configuration. \\ The umbrella was retained but now inside a plastic housing with a pre-umbrella oil separating screen. \\ Each 'breather valve' is assembled into a plastic fitting that is sealed over the outlet hole in the lower rocker box to the head breather bolt. \\ The new breather valves were also accompanied with new style hollow air cleaner mounting bolts for the pressure to escape. | ||
| * The new bolts are the same thread size as previous. \\ But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. | * The new bolts are the same thread size as previous. \\ But instead of a simple hex, it also has a shoulder past the hex for an O-ring to be fitted between the hex head and the air cleaner. | ||
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| == 91-03 == | == 91-03 == | ||
| - | 91-03 breather bolts. \\ | + | 91-03 breather bolts. \\ Outside threads are 1/2" x 13 (hole through the middle is 5/6" nominal). \\ |
| {{:techtalk:evo:carb:91-03_breather_bolts_1_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) {{:techtalk:evo:carb:91-03_breather_bolts_2_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) | {{:techtalk:evo:carb:91-03_breather_bolts_1_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) {{:techtalk:evo:carb:91-03_breather_bolts_2_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) | ||
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| They also allow the air to leave the vents at a faster rate. \\ | They also allow the air to leave the vents at a faster rate. \\ | ||
| - | 04+ breather bolts (small hole is nominally 1/16" or 1.5875 mm). ((tomcat of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=19)) ((Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=22)) ((http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) \\ | + | 04+ breather bolts. \\ Outside threads are 1/2" x 13 (2 different sizes thru the middle - nominally 1/16" (1.5875 mm) in the rear and 5/16" in the front). ((tomcat of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=19)) ((Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=22)) ((http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) \\ |
| {{:techtalk:evo:engmech:04_up_breather_bolt_3_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) {{:techtalk:evo:engmech:04_up_breather_bolt_2_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) {{:techtalk:evo:engmech:04_up_breather_bolt_1_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) | {{:techtalk:evo:engmech:04_up_breather_bolt_3_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) {{:techtalk:evo:engmech:04_up_breather_bolt_2_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) {{:techtalk:evo:engmech:04_up_breather_bolt_1_by_folkie.jpg?direct&300|}} ((photo by Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=5756327#post5756327)) | ||
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| {{:techtalk:evo:engmech:stainless-steel-breather-bolts-1_by_folkie.jpg?direct&300|}} {{:techtalk:evo:engmech:stainless-steel-breather-bolts-2_by_folkie.jpg?direct&300|}} | {{:techtalk:evo:engmech:stainless-steel-breather-bolts-1_by_folkie.jpg?direct&300|}} {{:techtalk:evo:engmech:stainless-steel-breather-bolts-2_by_folkie.jpg?direct&300|}} | ||
| + | ====== Symptoms of Breather problems ====== | ||
| + | Read more here on the [[techtalk:ref:engmech04#engine_breathing|Engine Breathing System]] in the REF section of the Sportsterpedia. \\ | ||
| + | The most noticeable signs of breather valve problems are weeping gaskets or oil excessively leaking out the breather or puking oil out of it. \\ | ||
| + | When the umbrella(s) gets hard, it doesn't flex well to allow the engine to breath out on exhale. \\ | ||
| + | Then the trapped in air is compounded on the next stroke. The excess air contributes to more vacuum created and implodes the gaskets. \\ | ||
| + | Or it contributes to too high of oil density and slings excess oil out. \\ | ||
| + | Other factors are involved so results will vary. \\ | ||
| \\ | \\ | ||
