If I remove the interior of the vacuum switch on the crankcase breather what differance will it make?
You will start over revving just like it does when the PCV valve is malfunctioning.
So that’s why it shuts at tick over. So even with a oil separator it will need to be there?
I guess by PCV switch you mean the PCV valve…
It’s basically a vacuum regulator, limits the vacuum so 1. idle doesn’t rise and 2. engine doesn’t start sucking up oil.
A oil separator is a good thing but will address only #2, you will still need a PCV valve to regulate vacuum.
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my pcv valve had packed up and i had been toying with the idea of an oil catch tank, so i set about buying a kit of parts to fit one, i cut the end of the pcv and removed the innards and refitted it to the air filter, i sealed the hole in the air filter that would normally let any oil in, i mounted a small glass oil catch tank to the wing brace bar, fitted a 19mm-10mm reducer to the air filter attachment and the crankcase rubber elbow and connected hoses to and from the catch tank, end result absolutely no change to engine running, and with 200 miles + and significant signs of oil in the catcher whole kit of parts under ÂŁ100.00
Nice set-up, but I don’t see the reason behind the negation of the PCV valve.
Your engine now sees full vacuum all the time, good for sucking fumes but also much more oil…
I wonder how long it would take for the separator bowl will to fill up, and what happens then?
What would be really cool is if there was a way to redirect the collected oil directly back to the sump, best of both worlds.
It also might cause the oil pump to cavitate.
full vac on that long small bore pipe is not high
hasnt sucked any oil out and at the milage i do it really doesnt matter if it does, just touch the button on the bottom and it would drop out (if it ever gets anything in there which i doubt) and others who have done the same have only got dirty condensation in there.
I believe that since the vacuum (decreased pressure compared with the atmosphere) is applied to both the oil pump intake and to its output (the entire circuit being within the crankcase), the pump itself does not see any change in its “head.” Similarly, I remember a lister some time ago suggesting that the pressure build up in the cooling system enhances the pressure (and thus flow) oft the water pump. Again, the uniform pressure change with respect to the atmospheric inside the cooling system doesn’t affect the pump’s pressure differential.
Neither the oil pump nor the water pump are “aware” of what their local equivalent of atmospheric pressure is. Conversely, a common problem on XJs is for the fuel tank pollution control to clog up, allowing the tank to go into vacuum as fuel is removed. That DOES affect the fuel pump, whose output IS referenced to the atmosphere. The result is that the pump in effect cavitates–it can’t generate the added pressure necessary to overcome the vacuum. Annoying–car dies in traffic.
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I installed a catch can on my other car, and it unfortunately did a great job sucking out water condensation. I had to empty it out weekly. Looked like chocolate water.
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