ET: Engine (Twin) Fram FV237 Breather

Bill Cannon

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So that means you had fitted it the right way round then Bill.
If that's the case it doesn't really help.
Have you blocked the timed breather off ?
I think you need to or the PCV valve won't operate correctly.
Cheers
Dave
I don't have a timed breather Dave as it's a D series engine.

Bill
 

tom wilson

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The Fram breather valve is a positive crankcase pressure valve i.e. it needs a few lb of crankcase pressure to open, I would suggest it is the pressure in the crankcase pushing out the oil. I suspect you would be better with a zero pressure crankcase valve.
 

Bill Cannon

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The Fram breather valve is a positive crankcase pressure valve i.e. it needs a few lb of crankcase pressure to open, I would suggest it is the pressure in the crankcase pushing out the oil. I suspect you would be better with a zero pressure crankcase valve.
Any recommendations?
Cheers Bill
 

BigEd

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The Fram breather valve is a positive crankcase pressure valve i.e. it needs a few lb of crankcase pressure to open, I would suggest it is the pressure in the crankcase pushing out the oil. I suspect you would be better with a zero pressure crankcase valve.
What is a zero pressure crankcase valve? It is not a term I have come across before. Is it a mechanical timed breather valve as standard on pre-"D" Vincent engines, etc.
 

tom wilson

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Any recommendations?
Cheers Bill
Hi Bill I have found some smaller ones that will fit a 1/4" internal bore pipe (with a diaphragm used on a Audi A4 PCV crankcase vent), that I have fitted to a 'D' breather cap. and a large bore 1/2" ball valve check valve (it rattles a bit if you listen hard) also if you do not mind fitting a Japanese part, the breather from a Yamaha XS 650 this is a reed valve engine breather and works very well if you can find somewhere to hide it out of view. Hope this helps. cheers
 

tom wilson

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What is a zero pressure crankcase valve? It is not a term I have come across before. Is it a mechanical one like the timed breather on the Vincent.
Hi Big Ed the best I could describe is a valve that opens with no or very little pressure, The Yamaha XS 650 read valve fits the bill in my mind, or the small PCV Crankcase Vent fitted to an Audi A4 or Passat as they require very little pressure to open.
 
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