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Author: Subject: Xflow breather
Matysiak

posted on 5/1/09 at 08:57 AM Reply With Quote
Xflow breather

I have a freshly rebuilt 1660 x flow that is let it's guts out every time i rev it, either though the dipstick or my breather bottle.

I have a breather catch tank connected to the standard tin box with the PCV valve (Centre removed) feeding it. The other pipe on the breather tank vents to the atmosphere. However, it fills the pint breather tank in a few minutes.

The oil level appears fine, although it is a customer made baffled/winged sump.

Is my set up wrong?

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Mr Whippy

posted on 5/1/09 at 09:14 AM Reply With Quote
I would be tempted to vent the rocker cover instead and block the old vent pipe connection. Does it stop if you remove the oil filler cap? It might be the new sump which could be not draining past the baffle quick enough and over filling (flooding) the back of the sump around the area which the PCV valve vent is located thus the oils being blown out. If so a few holes in the baffle may also cure this as shown in my rubbish picture Rescued attachment badpic.JPG
Rescued attachment badpic.JPG






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r1_pete

posted on 5/1/09 at 09:30 AM Reply With Quote
The pcv valve relies on inlet manifold vacuum to open it at higher revs and vent the crankcase. With your catch tank arrangement there is no vacuum to open the valve, hence the crankcase pressurises.

edit better ignore that you've bypassed the valve...

[Edited on 5/1/09 by r1_pete]






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procomp

posted on 5/1/09 at 09:32 AM Reply With Quote
Hi ^^^ eh block the block breather off and breath through the rocker only are you mad.

The regular way of a breather setup on the cross-flows is to take the breather from the block into the rocker cover and breathe the rocker cover into the catch tank using a 1" dia hose. Although it needs to be done with a bit of baffling so the rockers are not just pumping it out of the breather.
However if you are breathing that much oil out through the breather i would suggest getting a compression test done. I would suspect you are lacking a great deal of compression and blowing it past the rings and pressuring the sump hence the heavy breathing. Or seriously over filled the sump. Dose the sump that has been modded have a larger capacity of oil. Either way make sure you are not over filling on the dipstick. Is it throwing the oil out whilst stationary with revs or only when actualy driving.

Cheers Matt






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Matysiak

posted on 5/1/09 at 09:32 AM Reply With Quote
I removed the centre on the valve, it doesn't restrict anymore.
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Matysiak

posted on 5/1/09 at 09:38 AM Reply With Quote
It throws more oil out while driving, but if you rev while still a little comes out.

The sumps holds a lot more oil, but i an not sure how full it should be. Based on the dipstick i got with the engine (Before i rebuilt it) it looks fine.

I need to check. I am assuming that the oil level must only ever be in the deepest part of the sump, never getting into the shallower section where the rods can whip it up?

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Mr Whippy

posted on 5/1/09 at 09:52 AM Reply With Quote
quote:
Originally posted by Matysiak

I need to check. I am assuming that the oil level must only ever be in the deepest part of the sump, never getting into the shallower section where the rods can whip it up?


well that's what I was saying, if the baffle doesn't let the shallow section drain then it will be thrown all over the place by the crank. The oil pours out between the main bearings and will quickly fill a sump, even the back of it





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Matysiak

posted on 5/1/09 at 10:38 AM Reply With Quote
Now i understand. My sump doesn't have any baffling preventing it from flowing back into the deeper part. It just has a plate voevering the deeper part with several holes in it.
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rusty nuts

posted on 5/1/09 at 06:13 PM Reply With Quote
Lower the oil level to just above the minimum mark. My old engine used to leave a smoke screen behind if I booted it with the oil at max.
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