Breathing
Turbo Mini Forums

The recent spate of oil seal failures has got me thinking about engine breathing.

As I'm sure everyone here knows the standard the Mini relies on the inlet vacuum to suck the gas build up out of the crankcase, and I'm sure we all know that this isn't possible on a turbo due to the lack of a vacuum. Also running forged pistons which have a greater piston bore clearance and forced induction can only aggravate the matter and increase the crank case pressure.

Now it would appear that standard approach of fitting breathers to everything and sticking them in a catch tank isn't enough. Thinking back I remember reading in the yellow book about connecting the breather system up to the exhaust and effectively sucking the gas out of the crank case, for want of a better expression.

Has anyone tried this? as far as I can see it's got to be a good thing? providing that it's down stream of the lamba sensor of course. The only down side I can see is possibly the emissions test during a MoT but I suppose it could always be disconnected for the test.

Unfortunately my Dad has my copy of TBASE at the moment, so I can't do my home work.

I have been thinking about this a bit lately, i'm toying with the idea of adding a vacum pump, perhaps a servo pump from a desel would be enough?

I was thinking about this as well because of the problem with my primary gear oil seal.

You could just use an accumulator. A biggish tank that will hold manifold vacuum, a non-return valve, a couple of connections and a drain.

As long as you are not on WOT for too long, it should help.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

i've had a turbo mini for nearly 15 years and the only breathing/oil seal problem i have had is the primary gear oil seal. i now use the Black seal from the injection minis and had no problems since. even after melting a piston and driving 15 miles the oil seal didnt give up.

could your problem be linked to your piston/bore clearance or type of oil used or the type of oil seal?

i'm not saying your idea isnt a good one but could there not be a simpler solution as not everyone has this problem?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Indeed I was thinking in terms of my daily driver that always seems to seep a little oil just as a helping hand.

also have good experience with the brown oil seal ,it is double lipped and better : oil résistant !! (don't laugh) , no more slip and stress with all that oil on clutch plates

Just fit as many breathers as you can, and it should be fine.

Exhaust based extraction systems dont draw as much as you'd like. And if it didnt draw any vacuum at all, you could end up with no breathers.

There are various vacuum pump arrangements, and they are supposed to be very good. Either engine driven, or electric, but they are quite expensive.

Fitting lots of breathers into a catch can, is about the cheapest, and easiest.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will