Alfa Pages

[bobbber]

Anyone who has been looking at my posts talking about crankcase ventilation will know I have now closed the breather intake - and put one of those funky third party breathers on the oil segregation cap... like this:



However, I have since learned the crankcase is supposed to operate under a vacuum!!!! So, in a note, don't do what I did!

It's resulted in the oil sump gasket leaking, and also the oil filler cap popping off (it's now lying somewhere along the M5!!!)

Time to put it all back methinks, and think of some other way to sort out my problems!

Bob.
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Fiat Bravo 165 Sport

[Sprintervention]

Hi Bob,

This all seems a bit interesting...

I really can't see any reason why breathing your crankcase to atmosphere should cause any kind of sump leak, I supose that the breather may have caused your oil filler cap to pop off if it posed enough resistance though.

I say this is interesting as I run an 87 Sprint, no injection and a different breather system but the same basic engine, more or less.

It is common to find these breathing to the atmosphere, either by way of a filter as yours or through a catch tank and then filter. As far as I know this has never caused anyone any problems, indeed my own car runs with K&N filters and hence is breathing to atmosphere, and it has caused me no ill.

I supose that the injection system could be upset by a change in MAP caused by the removal of a breather hose from the plenum, but then I don't think that Alfa uses MAP sensors in its injection.

Anyway, hope you get sorted out.

Chris

[Eddie W]

Hi Bob, all crankcases operate under positive pressure unless drysumped(see lubrication post in Racing). The only reason that the c/case is vented to the inlet is emissions. Racing applications would almost universally be vented to atmosphere and frequently require extra venting to prevent gasket leakage. If you have popped a crankcase filter off then you must have had a restriction causing pressure buildup. Try feeding your c/case pressure to a catch tank with a larger filterand remember that filters can easily become clogged and therefor restrict. The wire mesh as used on the S3 motors slows the air down so that the oil in the vapuor can drop out of suspension. This is a good system and can be incorporated before a filter such as you used.
Regards Eddie
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