Crankcase ventilation, without the hassle?

[bmcecosse]

It may bleed off pressure - along with nasty carcinogenic fumes.......far better to suck the fumes away and burn them. I do wonder if you are getting enough suction there Fin - usually the connection would be to the manifold. But if it's working...leave well alone !

[katy]

Make sure you plug every source of infiltration air

Did you do that? Including the breather on the side cover?

[Fingolfin]

I believe the remaining oil loss (which was surprisingly substantial on my recent 130-mile drive) is due to leakage from bad gasketing/sealing, and not due to the PCV system. It seems to have reduced the leaks some. I did not in fact close off the tappet chest breather, which I may yet do (how?), but there seem to be no other apertures, except possibly the oil filler cap.

However, I am aware I did not succeed with the new sump cork seals, and I must do this again soon; more importantly, I was fool enough to not notice that the oil pump has no gasket when I had the engine backplate off last Christmas, and having removed the oil pump for inspection, I broke the "age seal." Leaks have been pretty bad from the backplate since, even through the new backplate gasket. As this requires engine removal to remedy, it hasn't been fixed yet.

I shall continue experimentation. Remember, folks, for all my years of experience at Minoring, I am yet an amateur.

[Declan_Burns]

Fin,
Try fitting the U-tube as I have shown-it's simple but works perfectly for set-up . You should be able to see the results immediately as you start blocking off any leaky sources e.g. try plugging the oil filler cap and the tappet chest vent.
Regards
Declan

[bmcecosse]

I prefer to leave the cam follower chest breather OPEN - but extended slightly (rubber tube) down into the airstream under the car. Thus in extreme use if there is excessive fume (and little suction when the engine is working full throttle) the fumes can escape without pushing out past seals/gaskets etc. My engine is far from 'new' - but is oil tight. And there is some evidence of oil streaking on the underside of the car - I like to think of it as rust prevention.... And it doesn't drip on the drive - Mrs bmc would soon spot that...... In normal use I suppose air is drawn up through the open tube, thus venting the crankcase and causing moisture to be drawn through and burned. Certainly no 'mayo' in the rocker cover.
I don't get your 'no oil pump gasket' Fin - do you really mean there is no gasket between the oil pump and the block face where it bolts up??? If so - rectify that asap....
Oil dribbling down the sump side of the backplate is leaking sump gaskets - oil dribbling from the jiggle pin in the base of the bellhousing is escaping past the labyrinth 'seal' in the rear of the crankshaft - caused by excessive crankcase pressure and/or excessive oil leaking out of a worn rear main bearing.......

[Fingolfin]

Yes, that is indeed what I mean, Roy -- somehow there was no gasket present under the oil pump and I was fool enough (or, shall we say, too pressed for time) to notice it. It's already on the list, but it's got to wait for an extended break from school -- Christmas probably. Haven't had any "mayo."

Oil is clearly coming down the backplate side (front face) mostly, which is the oil pump, but there is a far lesser amount down both front and rear faces of the sump, which is the cork seals. There is virtually none from the jiggle pin, and none from the timing chain cover (since I replaced it with the later rubber-seal version).

Declan, I will get a T-piece and see if the local auto parts shop will lend me a vacuum gauge. And I'll see about a closed oil filler cap, and try extending the tappet chest breather downward.

[MarkyB]

Smoking at start up is generally worn valve guides, no need for an engine rebuild.

[Fingolfin]

That's a fair point. I suspect the engine as a whole needs a rebuild, but I could do the head separately.

[Declan_Burns]

Fin,
You just need some clear plastic tube from the DIY and a few drops of water-no fancy gauges. Standard dial gauges will not work at such low pressures. We are trying to measure millimetres of water. A 10mm difference in water level in the U-tube=1mbar. For the test just tape over the vent on the oil filler cap and plug the pipe on the tappet chest with a bung. You need to block off all Infiltration air sources. It has to be a closed system to work. You will see if it is working instantly as the water level changes quickly.
I would also advise you to replace the cork sump seals with the rubber ones from the 1275 engine which need to be trimmed to fit-although some of the modern cork seals are now impregnated with silicone. I gave up on the old cork seals years ago.
The rubber seal works a treat. I have no oil leaks.
Regards
Declan

[Fingolfin]

Ah, well that sounds much easier. Thanks for that, Declan! Looks like I have a trip to the hardware store in my future (which is always one of my favorite things to do)!

I shall investigate the 1275 sump seals. I think the cork seals failed because I soaked them overnight in oil first, and this caused them to swell such that I had to cut them down too much to make them fit. I think unsoaked cork would work better, but like I say, the rubber ones are worth looking into.

[bmcecosse]

Nothing wrong with cork seals - I don't have any leaks........

[Matt]

what about your car BMC???

[bmcecosse]

Hehehehehe - no it's leak tight too.....

[alexmcguffie]

Just seen this post.

Using a servo vacuum take off for a crank breather is wrong. You would effectively have a hole open to atmosphere on the wrong side of the butterfly valve. The engine would run far too weak and eventually burn a valve out.

If you think about it, the vacuum port on a servo is a dead end so has no effect on the carburation.

If you want to recirculate the breater then you should use the inlet side of the carb, otherwise use a catch tank.

[bmcecosse]

The servo port method is well proven to work like a dream - the hole is reduced to 1/8" diameter and the mixture set accordingly. It is exactly how the 'closed circuit' system works -with the addition of a little flap valve of course.

[Fingolfin]

It's precisely the same thing as having a carb inlet -- just at a different place in the bore! And the vent I devised is hardly open to the atmosphere, since it's "after" the butterfly valve (that is, it's between the carburetor and the manifold). The vacuum produced by the engine will naturally cause any fumes to be drawn inward. And the engine most certainly has not been running weak; I've done fifteen hundred miles since fitting this system and have had no apparent problems.