14 replies to this topic

[Clip]

I have a 1100S motor (now1310), so it has the flywheel side breather assembly, but it also has a rocker cover breather. These are both connected together and then a single line to HIF44 carby. No PCV valve. Do I need both? Should I run a PCV valve, or should I just vent to atmosphere via those little air filter things?

[Steam]

The way your breathers are connected is one way of doing it, there are others.
Most A series engines tend to create some blowby and crank rotational pressure and some will blow the dipstick out as well as oil.
I have always found the best way for me is to connect the rocker cover inlet to the air filter to allow air in and connect the breather cannister to the carb to draw air through the emgine. No PCV needed. There should be some form of filter media in the cannister already to stop the worst of the oil / vapour from getting into the carb.
If you just put filters on the breathers it will probably blow oil out.

[Ethel]

The factory system creates a little bit of a depression that helps to in keeping the oil from escaping past the oil seals. The restrictive size of the breather hole in the oil filler cap does it.

 

More than one oil separator  means there's an alternative path for the suction if one gets overloaded so much it struggles to drain back.

[Lplus]

I have a 1100S motor (now1310), so it has the flywheel side breather assembly, but it also has a rocker cover breather. These are both connected together and then a single line to HIF44 carby. No PCV valve. Do I need both? Should I run a PCV valve, or should I just vent to atmosphere via those little air filter things?

Leave them as they are.  The oil filler cap should be a breather type.  The pcv valve is for use when the breathers are connected direct to the inlet manifold.  My 1100 estate has one breather from the tappet cover to the breather inlet on the carb and a breather type oil cap.  Works fine.

[timmy850]

I’ve tried a few different breather setups
Open breathers are easy but a bit smelly and rely on the blowby to just waft out
The connection to the carb port is really good as it sucks the blowby out of the engine, but a catch can might help in keeping the oil out on the intake.
PCV system is the most complex and can have issues if you have more than one source of intake air. As it goes to the manifold, any leaks will cause a high idle.

Having the rocker cover and clutch housing breathers means you’ve got one on the top and bottom of the pistons, so it should equalise the pressure.

[Clip]

Thanks folks, much appreciate your comments. I think I’ll leave it as is then. The filler cap is a breather type too. I like the idea of catch-can Tim as I always fit them to any diesel cars that I own. I just don’t really have anywhere to put one on the mini after I fit the brake booster, washer bottle and coolant overflow bottle!

[Spider]

A little late to the party but to add another voice and view here.

The crankcase outlet on the Flywheel housing is the one to use. If you feel you want a second one, fit one to the timing chain cover.

The one on the rocker cover,,,, it's the wrong rocker cover you have. Plug that one up and fit a vented cap.

Whether you plumb it up as a PCV or a CCV system depends on your choice of Carb, personally, I have found the CCV to be a very good set up.

With any crankcase breather system, you need to draw fresh filtered air in to one part of the crankcase, through as much of the crankcase as you realistically can (and well above the natural oil level) in order to not just draw off blow by but also remove water vapor that forms as part of blow by. The water vapor combines with the oil to form that 'mayo' you find under the rocker cover and it also forms acids in the oil, both of which are quite undesirable.

With the factor oil separators, this is one thing the factory got very right, especially when plumbed as a CCV System.

[Clip]

Thanks Spider, that’s interesting. I thought it was a bit of a mishmash having the rocker cover and crankcase breather, and also having the vented oil filler cap.

 

Current setup:

[Lplus]

Thanks Spider, that’s interesting. I thought it was a bit of a mishmash having the rocker cover and crankcase breather, and also having the vented oil filler cap.

 

Current setup:

It does look like that rocker cover was specifically made for that setup, having an oil trap set into it.  Still not sure I would mess with it, though I can see spider's point about drawing air through as much of the engine as possible. 

[timmy850]

Yes that’s an Aussie made rocker cover with a baffled breather

They made a couple of different types, some had the breather on the other side

[Spider]

Thanks Spider, that’s interesting. I thought it was a bit of a mishmash having the rocker cover and crankcase breather, and also having the vented oil filler cap.

 

Current setup:

 

Yeah, that's not really going to work too well !

Fresh air in via the filler cap and then routed off via the rocker cover.

The Rocker Cover is off a Mini K.

[Clip]

So in the aim of looking clean and neat, I’m thinking I should change out the rocker cover for one that takes the vented cap, but no breather?

[Spider]

So in the aim of looking clean and neat, I’m thinking I should change out the rocker cover for one that takes the vented cap, but no breather?

 

All stock Rocker Covers will take the Vented or Sealed Caps.

 

For a neat install, yes, I'd suggest a 'blank' rocker cover, which was in fact what these engines had from the factory.

[Clip]

Thanks again Spider. One last question, do the new alloy covers from mini spares etc. use a vented cap? Their descriptions don’t mention it.

[Spider]

Thanks again Spider. One last question, do the new alloy covers from mini spares etc. use a vented cap? Their descriptions don’t mention it.

 

The MG Metro type cover is the only one I have seen in recent times that I would recommend, the replicas also seem OK. These do have a vented (and filtered) cap with them. There's another type, that seems common, cheap and popular that I find is little more than junk. The caps are a poor fit and while vented are definitely not filtered.