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techtalk:evo:engmech07 [2020/02/10 17:03]
hippysmack [Sub Documents]
techtalk:evo:engmech07 [2020/09/14 04:24] (current)
hippysmack [2004-Present Engine Breathing]
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 See also in the REF section of the Sportsterpedia:​ \\ See also in the REF section of the Sportsterpedia:​ \\
   * [[techtalk:​ref:​engmech04|Evo Crankcase Pressure]]   * [[techtalk:​ref:​engmech04|Evo Crankcase Pressure]]
-  * [[techtalk:​ref:​engmech05|Breather ​Vent Relocation]]+  * [[techtalk:​ref:​engmech05|Breather ​Venting / Relocation]]
  
 <​blockquote>​Crankcase ventilation works a little differently on these motors than a Chevy. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1468237)) \\ <​blockquote>​Crankcase ventilation works a little differently on these motors than a Chevy. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1468237)) \\
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 ====== Late 1984-1990 Engine Breathing ====== ====== Late 1984-1990 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. \\
 +See the link at the top of the page for aftermarket breather and venting solutions. \\
  
   * 86-90 engines continued the breather baffle tube system from previous year models incorporated into the cam cover in the area behind the 86 style oil filter.   * 86-90 engines continued the breather baffle tube system from previous year models incorporated into the cam cover in the area behind the 86 style oil filter.
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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. \\
 +See the link at the top of the page for aftermarket breather and venting solutions. \\
 +
   * 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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   * The Parts Catalog and FSM are a bit confusing regarding how many umbrellas are used and where. \\ The information is there but it's just not clear. \\ The parts catalog only shows an exploded diagram of one rocker box assembly on the Rocker Arms, Covers and Pushrods page. \\ Yet, the description shows that 2 umbrellas are required. \\ It's the same for all of the parts on that page as well as each newer parts catalog (1 pushrod, tube ,lifter and related parts). \\ This is the norm mostly throughout the subsequent catalogs with multiple (same) parts. \\ It's assumed this was done to save money on printing the catalogs (replicated information deleted). \\ The FSM displays the same exploded diagram as the parts catalog in the front of the Cylinder Head section. \\ It's only at the end of the Installation article does it say to install new gaskets on the middle rocker box (with the breather valve on the intake side). \\ There is no dedicated section on the rocker box or umbrella valves (which seem to be regarded as mere gaskets).   * The Parts Catalog and FSM are a bit confusing regarding how many umbrellas are used and where. \\ The information is there but it's just not clear. \\ The parts catalog only shows an exploded diagram of one rocker box assembly on the Rocker Arms, Covers and Pushrods page. \\ Yet, the description shows that 2 umbrellas are required. \\ It's the same for all of the parts on that page as well as each newer parts catalog (1 pushrod, tube ,lifter and related parts). \\ This is the norm mostly throughout the subsequent catalogs with multiple (same) parts. \\ It's assumed this was done to save money on printing the catalogs (replicated information deleted). \\ The FSM displays the same exploded diagram as the parts catalog in the front of the Cylinder Head section. \\ It's only at the end of the Installation article does it say to install new gaskets on the middle rocker box (with the breather valve on the intake side). \\ There is no dedicated section on the rocker box or umbrella valves (which seem to be regarded as mere gaskets).
- 
  
 **Installation** \\ **Installation** \\
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 |{{:​techtalk:​evo:​oil:​umbrella_valves_by_erik.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_by_phillober.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_locations_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​umbrella_valves_by_erik.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_by_phillober.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​umbrella_valve_locations_by_hippysmack.jpg?​direct&​300|}}|
-|  Umbrella Valve (only 1 installed per rocker box) ((photo by Eric of the XLFORUM ​ http://​xlforum.net/​forums/​showthread.php?​t=382922)) ((photo by Phillober of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=3345764#​post3345764)) ​ ||  Umbrella Valve Installed Locations ((photos ​by Hippysmack)) ​ |+|  Umbrella Valve (only 1 installed per rocker box) ((photo by Eric of the XLFORUM ​ http://​xlforum.net/​forums/​showthread.php?​t=382922)) ((photo by Phillober of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=3345764#​post3345764)) ​ ||  Umbrella Valve Installed Locations ((photo by Hippysmack)) ​ |
  
 |{{:​techtalk:​evo:​oil:​head_breather_holes_1_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_2_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_3_by_hippysmack.jpg?​direct&​300|}}| |{{:​techtalk:​evo:​oil:​head_breather_holes_1_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_2_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​oil:​head_breather_holes_3_by_hippysmack.jpg?​direct&​300|}}|
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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. \\
 +See the link at the top of the page for aftermarket breather and venting solutions. \\
 +
   * 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)) ​