From my understanding, the purpose of the oil breather is to vent off residual fuel and oil VAPORS. So, if we’re dealing with VAPORS, what is the purpose of the breather screen and filter? How often should they be changed? Also, if one is removing the front cover and breather housing assembly, will oil spill out, or does one have to drain the oil?
Lastly…I’m having the triple SU conversion done. How much damper oil is put into the reservoir of each carburetor? It sure would be nice if some basic instructions were included whenever any part is ordered!
If you take the breather part off to clean the gauze mesh ( like I did ) , make sure the gaskets ( 2 ) are in good order and re-fitted , and that all the nuts are tightened properly , otherwise , oil will escape and run down onto the crankshaft damper ( don`t ask me how I know ).
Gary , its catching the oil blow by…
The front cover should be removed every so often and clean the screen down. If not and the screen clogs , the engine will build up back pressure and it will push out the exhaust as bellows of smoke in extreme cases.
You didnt state what year but you should have a RETURN pipe back to the air inlet if its a 4.2 to burn the un burnt gases
Good luck
gtjoey1314
As Joey says the breather screen needs to be cleaned every now and then. If it clogs it allows the crankcase pressure to increase and can push oil out past the rear crank seal ultimately causing it to fail.
The item people may be suggesting you remove, the oil breather, is about 5 inches in diameter, held on by 4 nuts. No one is suggesting that you remove the whole front cover of the engine, thus spillage of a substantial quantity of oil is unlikely. However, as for vapor vs liquid oil, right behind the oil breather are camshaft chains. They get lubricated with oil and an engine spinning at several thousand rpms will throw off liquid oil in all directions from those chains, some of it hitting the inside face of the oil breather and its wire gauze filter. The filter is metal wire gauze, cleanable, and is not usually replaced like an engine oil filter would be, although the filter is available if it is damaged or missing.
I have heard that the fine gauze mesh in the breather can clog up but mine was 100 % clean and AFAIK had not been removed for years . Not sure how this could become blocked , and if it did , it`s likely the engine would have big problems elsewhere .
This episode of Wheeler Dealers demonstrates the dirty breather screen and associated blue smoke and removing and cleaning the screen. Seems to have solved the blue smoke problem they had on their MK 2.