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techtalk:ref:oil10b [2020/10/04 18:18]
hippysmack [Oil Tank's Role vs Wetsumping]
techtalk:ref:oil10b [2024/01/19 03:17] (current)
hippysmack
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 ====== REF: Oiling & Lubrication - Sub-10B ====== ====== REF: Oiling & Lubrication - Sub-10B ======
 \\ \\
-====== ​Oil Tank's Role vs Wetsumping ​====== +====== ​Bad Ring Seal vs Wet sumping ​======
-See the full article, [[techtalk:​ref:​oil04#​oil_tank_pressure|Oil Tank Pressure]], in the REF section of the Sportsterpedia. \\+
  
-There should not be any pressure difference in the oil tank than the engine although it does transfer pressure. \\ +===== Bad Ring Seal vs Wet sumping ===== 
-The oil tank vent line to the cam chest allows the pump to send oil and CC pressure to the tank without over pressurizing the inside\\ +Wet sumping and oil spatters from the crankcase are two different things((Jorgen of the XLFORUM https://www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-engine-conversions/​38153-xr750-883-series-race-engine-venting-etc/​page7?t=75740&highlight=reed+valve&​page=7)) \\ 
-It is not there to vent the cam chest, the breathers do that. \\ +Daily driver owners with oily air cleaners can get these two ideas confused. ​\\
-{{:techtalk:​ref:​oil:​oil_pressure_drawing_3_by_hippysmack.jpg?direct&450|}} ((drawing by Hippysmack)) \\+
  
-**During normal operation**; ​\\ +Bad ring seal helps evaquate the sump from oil. \\ 
-With the tank cap / dipstick removedtank pressure is vented to atmosphere from the top of the tank. \\  +But on the other handit increases ​the flow rate through ​the crank vent system to such levels that a lot of oil droplets join in. \\ 
-With the tank cap / dipstick installedtank pressure ​is vented ​to the cam chest. \\+Apart from leaking cylinder base gaskets and push rod tubeslarge blowby and high crank pressure ​also contributes ​to even larger ring leakage. \\ 
 +It's a vicious circle. \\
  
-So if you have pressure ​in your oil tank and the vent to the cam chest is not blocked then the cam chest is also pressurized. \\ +Sometimes owners who struggle with an oily air cleaner problem seem more concerned with wet sumping. \\ 
-If the cam chest is holding pressure, then your breather valve can not be venting properly. \\+When they should concentrate ​in evaluating ​and improving ring seal. \\ 
 +And ideally also route the crankcase breather lines to a catch tank instead of the A/C. \\ 
 +Re-routing ​the vent(s) from the breather to a catchtank has many advantages. \\ 
 +Not least it is a powerful tool to monitor the state of the engine. \\ 
 +There should be more water than oil in the catch tank. \\ 
 +At least if air temp is 20C or below. \\
  
-Bottom line is that if the vent system is working properly, you shouldn'​t have excessive pressure build up in the oil tank. ((Deimus of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=87313)) ​\\+\\
  
-It has been said by many that lowering the oil level in the oil tank will stop oil puking out the breather. \\ +[[:techtalk:​menu|{{:​techtalk:​gototechnicalmenu.jpg|}}]]
-While this may work in application,​ by design, you should not have to lower the oil level. \\ +
-This practice is not just restricted to rubbermounts although due to the CC pressure change in 04, it is a more accepted practice. \\ +
-The tank acts as an oil / air separator like the breather valve but the air only expels the engine from the engine breather vent. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1971026&​page=28)) \\+
  
-====== Lowering the oil level in the tank ====== 
  
-** *When you lower the oil level in the tank, you are just masking the real problem* ** . \\ 
-Below are some arguments for lowering the oil level with responses below them. \\ 
-Basically myths and truths. \\ 
- 
-  - **The oil vent line in the oil tank is too close in height to the full mark.** 
-    * The vent line is actually higher than the full mark. 
-    * If the engine breathers are working properly, the oil level in the tank should never get high enough to enter the vent line. 
-    * If there is an engine breathing problem, \\ The tank vent will not flow separated air back into the cam chest fast enough to keep up with the incoming flow of oil in the tank. 
-    * The oil / air backs up in the tank, but pressure is steadily coming up the scavenge line from the pump. 
-    * Aerated oil will take up more space volume than non-aerated oil. 
-    * Then the result could be oil (backed up) running back down this vent line into the cam chest during operation (acceleration and braking). 
-    * Below pic below is of an 04-09 oil tank with the top and bottom separated. 
-      * You can see how high the oil has to rise to get into the vent tube. It basically has to fill up the tank first. ((photos by cootertwo of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​threadid=148936)) \\ {{:​techtalk:​ref:​engmech:​oil_tank_3_by_cootertwo.jpg?​direct&​300|}} \\ \\ {{:​techtalk:​ref:​engmech:​oil_tank_1_by_cootertwo.jpg?​direct&​300|}} {{:​techtalk:​ref:​engmech:​oil_tank_2_by_cootertwo.jpg?​direct&​300|}} {{:​techtalk:​ref:​engmech:​oil_tank_4_by_cootertwo.jpg?​direct&​300|}} 
-  - **The extra oil in the bottom end is thrown around more inside the engine and finds it's way up into the heads during the breathing operation. \\ This excess oil is then purged out the head breathers.** \\ 
-    * Any oil that leaves the vent in the oil tank flows back into the cam chest then gets scavenged via the cam chest port in the pump. 
-    * All oil in the cam chest can be subject to being picked up into suspension no matter of it's origin. 
-  - **Having too much oil in the tank will cause more blowby**. \\ 
-    * Too much oil in the tank does not cause more blowby. ((bustert of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657)) 
-    * Oil in the engine must: 
-      * 1. Lube 
-      * 2. Clean 
-      * 3. Cool 
-    * If you take away what the factory says to run then you take away from one or all of those 3 properties. 
-    * Blowby is a condition when air pressure blows by the rings or valves. 
-    * Blowby has some to do with oil puking out the breathers, but it doesn'​t cause it by itself. 
-    * Oil puking out the breathers is an imbalance in the breathing system which may or may not have to do with the rings or valves. 
-    * The oil level only matters if the tank has been overfilled past the top mark on the dipstick. ((Toejam503 of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5750657&​highlight=lower+oil+level#​post5750657)) 
-    * This is easy to do if you check the oil level and fill the tank BEFORE heating up the engine to operating temperature. \\ See more about [[techtalk:​ref:​oil01#​overfilling_the_oil_tank|Over filling the oil tank]] in the REF section of the Sportsterpedia. 
-    * Overfilling the oil tank can bring the level up over the vent to the crankcase. \\ This would stop up the vent to the cam chest, over-pressurize the tank and hinder scavenging from the sump. \\ Increased sump oil (not able to be scavenged fast enough) aides in oil suspension or air /oil density increasing crankcase pressure. \\ Increased crankcase pressure aides in oil puking out the vents. 
-  - **Running the oil level on the bottom dipstick line helps curb blowby. \\ Running the oil level at the middle to high side of the dipstick causes more blowby.** \\ 
-    * Running the oil level on the low mark of the stick effectually lowers the amount of oil that would collect in the sump. 
-    * It also lowers the amount of oil circulating which could raise oil temps and starve mechanical parts of oil. \\ (I.E. lifters, rockers, bearings etc.) 
-    * Lowering the amount of oil in the sump also leaves less oil there to get pulled up into suspension which thins out air / oil mist. 
-    * It's the more dense air / oil mist that is the problem, not the oil level in the tank. \\ 
-    * Many people say that it is important to leave plenty of empty space in your oil tank. ((Deimus of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=72099&​highlight=wet+sumping&​page=21)) \\ 
-      * If you don't have excess crankcase pressure, you don't have to do that. You can fill the oil tank to the full mark on the dipstick without any issue. 
-      * The oil tank is a sealed space with a seal / O-ring on the dipstick. \\ The oil tank space is connected to the crankcase space via the vent hose that runs from the oil tank to the cam cover. \\ By filling the oil tank only half full, you create a larger air volume in the crankcase space itself. \\ This increased air volume can help buffer the pressure in an engine with only a slight problem with blow-by gasses combined with the restricted head vents. 
-      * However, if you either; 
-        * Restore your engine to like new low levels of blow-by. 
-        * Or if you improve the engine'​s ability to vent the pressure. \\ Then you don't need the extra buffer space provided by half filling your oil tank. \\ You can go ahead and fill your tank with the proper amount of oil. \\ Which means you have more oil to circulate through the engine which is a good thing. 
- 
-**So the answer is to address the air/oil density, not the oil level.** 
- 
-====== Removing the oil cap - engine running ====== 
- 
-With the oil cap off the tank on a hot idling engine (so far rigid S models only), the engine speed can drop app. 1,000 RPM at 1050 idle. ((Hippysmack of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5763694#​post5763694)) \\ 
- 
-Another example with oil temp 210, raised idle to 1200 and lost 700 RPM. \\ 
-So the exact power loss is variable but true. \\ 
-Barely opening the cap or fully removing it had no affect on RPM. \\ 
- 
-This is the same as having a bad breather valve opening but not closing. \\ 
-Oil doesn'​t puke out the tank since higher density suspension oil comes up the return line from the sump. \\ 
-The suspension fluid and return oil together in the line helps to separate the oil back out of suspension by the time it reaches the tank. \\ 
-The bulk of air / oil mist is generated in the crankcase, not the cam chest where the vent line to the tank is. \\ 
-(leaving most of what comes out the top of the oil tank to be air). \\ 
-The higher air/oil density drags the flywheels and more oil is picked up in suspension with the engine breathing both in and out. \\ 
-The engine responds at idle from the higher load on the wheels. \\ 
-Read more on [[techtalk:​ref:​engmech04#​fluid_drag|Fluid Drag]] above. \\ 
- 
-====== Venting the oil tank ====== 
-Neither the oil cap nor the oil tank should be vented without a one way check valve / pcv. \\ 
-The tank is vented to the cam chest on purpose to remove condensate (that gets pumped in) from the oil tank. \\ 
-Venting the oil tank \ cap also will negatively influence crankcase venting by letting in extra air. \\ 
-1/2 of the return flow is air because the return pump is twice as big as the feed pump. ((ryder rick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1904589&​page=4)) \\ 
-That air is full of condensate. \\ 
-A slightly negative (to atmospheric) pressure in the tank facilitates vaporization of the condensate. \\ 
- 
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-\\ 
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-[[:​techtalk:​menu|{{:​techtalk:​gototechnicalmenu.jpg|}}]]