| Author | Message | ||
     Chris Miller Experienced User Username: cjm51213 Post Number: 16 Registered: 5-2013 |
Hi Folks, I found the breather and I now know the procedure to clean the screen. I've heard that a clogged screen will cause greater then normal oil leakage at the engine crankshaft. I'm confused. Positive crankcase pressure will increase oil leakage at the crankshaft and this breather is supposed to provide an outlet for crankcase pressure which would be disabled by a clogged screen, but this thing looks to me like it creates positive crankcase pressure! How is this supposed to work? Thanks for the help, Chris. | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 108 Registered: 10-2008 |
Chris, check the condition of the cork seal on the oil filler cap also. If this is worn then the crankcase breather will not work , Replacing this on my Spirit has dramaticaly reduced the oil leakage when running. Mark | ||
| David Lacey Experienced User Username: dlacey Post Number: 14 Registered: 11-2010 |
Chris, Positive Crankcase Ventilation is normally a way to reduce the pressure in the crankcase below atmosphere. http://en.wikipedia.org/wiki/Crankcase_ventilation_system My experience is mostly with Jag V12s where a blocked PCV will cause a massive rear main leak as the oil is blown past the 'seal'/scroll/thrower. In the RR case, without knowing the details, i expect the breather should create a pressure slightly lower than atmosphere...clogged screens & collapsed hoses will limit this vacuum and the crankcase pressure will rise. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2885 Registered: 4-2003 |
The system is positive crankcase ventilation. The other option would have been to have a breather pipe, ie no positive ventilation. On the SY cars the ventilation relies on the air resistance of the trunking and air filter to provide a depression in the crankcase. So, those clever chaps who put in low-resistance air filters not only mess up the carburettor jetting requirements, but also introduce engine leaks. Later Crewe cars (SZ) have a combination of induction manifold venting and the primary air resistance to produce a greater depression at low engine loads. Turbos require a few one-way valves to keep it all working when the inlet manifold is under boost. The primary venting works best when most needed - on load, whereas the induction manifold does the reverse. Turbo cars have their depression regulated to not more than 20cm H2O by a diaphragm and spring in their flame trap modules. The naturally-aspirated SY and SZ cars have no regulator and have about 7cm H2O depression. RT. 2 | ||
| richard george yeaman Prolific User Username: richyrich Post Number: 108 Registered: 4-2012 |
Richard. I replaced the wire mesh air filters on my Shadow 1 to a one piece Cylindrical paper one, Which type in your opinion would be the correct one to use to give the best results. Richard. |
