Re: Where to connect the Oil Tank Breather hose on 850 Comma
Mark Cigainero said:
Should I just connect the breather hose to the rubber crosssover line on the intake manifolds in front of the carbs???
I wouldn't do that, as you would be introducing an 'air leak' into the inlets? Air would be sucked in by the engine, resulting in a weak mixture. The original system worked because the oil separator vented into the airbox
as well as being connected to the balance pipe tee, therefore the depression in the separator pipe is equal to the depression in the carb inlets, so air doesn't get sucked into the engine from the separator pipe.
Mark Cigainero said:
Will it harm anything if I just plug it up as it leaves the top of the oil tank??? What is the purpose of this breather hose??? Thanks---Mark C
No, don't plug it up.
1. The crankcase breather pipe is connected to the oil tank normally, so the tank must have an atmospheric vent for the breather to work.
2. The return side of the oil pump has double the delivery rate of the feed side in order to remove any accumulation of oil from the sump and keep the sump clear by being able to empty it faster than the feed side can fill it, this means that the scavenge pump will normally pick up large amounts of air as well as oil, which ends up getting pumped into the oil tank.
That air needs to be allowed to escape from the tank, otherwise the air pressure inside the oil tank could possibly rise to a level that would restrict the return oil flow to the tank or cause pipe joint leaks or even cause the oil pipes to blow off their spigots.
Although in reality I expect a large amount of that air pressure would leak from the filler cap seal?
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Graeme posted ahead of me as I was typing this, as I was also going to suggest you run the vent pipe into a small plastic bottle catch tank to collect any oil mist as I have done on my own Mk3 with custom air filters.
