Rocker cover breather

Post by **winger300** » Mon Feb 23, 2004 12:26 am

My current setup consists of a mushroom type air filter housing, and a rocker cover breather pipe connecting to the air filter housing.

When i change my carb and filter for a K&N, what do i do with the rocker cover breather pipe?

This is probably one of many things i've overlooked for my cylinder head change. Any advice on things to watch out for? changing to HS4 carb.

I've succesfully seperated my exhaust manifold from the inlet, to use an alloy inlet.

Thanks

Post by **brixtonmorris** » Mon Feb 23, 2004 10:14 am

some minor rocker boxes dont have breather pipe

Post by **rayofleamington** » Mon Feb 23, 2004 12:38 pm

You can get K&N pancake filters that have a connection for the breather. I've only seen 1 so they're probably difficult to find second hand.

Post by **Peetee** » Mon Feb 23, 2004 12:44 pm

I have seen Mini's with matching K&N breather filters. Try a good Mini spares supplier.

Post by **Cam** » Mon Feb 23, 2004 1:01 pm

I have the same. A K&N breather filter (about £12 from Minispares).

Post by **edd** » Mon Feb 23, 2004 2:00 pm

some minor rocker boxes dont have breather pipe

arn't they the on the later engines with the mushroom shaped breather going into the manifold?

Post by **winger300** » Mon Feb 23, 2004 4:30 pm

Thanks,

i just got a K&N one on ebay for £7.

Post by **brixtonmorris** » Mon Feb 23, 2004 6:15 pm

those rocker boxes are from are from late split screen may be some early 1ooos , but not realy sure.
i have a few around though.

Post by **brixtonmorris** » Mon Feb 23, 2004 6:20 pm

on my own morris i leave the pipe of the air filter, i find it makes the air filter oily.

Post by **rayofleamington** » Mon Feb 23, 2004 6:32 pm

i find it makes the air filter oily.

I thought that meant it's working.

Post by **brixtonmorris** » Mon Feb 23, 2004 6:48 pm

why would one want to add vaporised old rocker box oil to the air filter. some morris when they came to the garage had so much oil on the filters the filters they were saturated

Post by **brixtonmorris** » Mon Feb 23, 2004 6:49 pm

morris designed it so it should be there, but i like my filter clean

Post by **Willie** » Mon Feb 23, 2004 7:00 pm

BRIXTON...it is always worth checking the size of the inlet
hole where the rubber pipe joins the filter. it should be about
1/8". if it is about 3/8" then it is NOT a proper Minor filter and
will suck too much oil into the filter. (I have never discovered
what car this type comes from)

Post by **Gareth** » Mon Feb 23, 2004 7:01 pm

I think it's part of an environmental issue, isn't it? Instead of road-draught breathing, the engine is a closed-breathing circuit, with any air in the rocker area being routed through the air-inlet assembly. On early cars (with the saucepan filter) it went in through the air filter housing, but on later cars it re-entered the engine direct to the inlet, after the filter.

Post by **brixtonmorris** » Mon Feb 23, 2004 7:13 pm

i think youve got it there gareth
i so bad driving around like that

Post by **brixtonmorris** » Mon Feb 23, 2004 7:20 pm

ive noticed that, but never thought about the hole size. you realy know your stuff Wille

theres a lot of the 3/8 hole base around

Post by **rayofleamington** » Mon Feb 23, 2004 7:32 pm

theres a lot of the 3/8 hole base around

I was keeping quiet for the last few months - I once had one with a big hole, and an oily filter. But I never connected the obvious..

I have no idea which car the 'big hole' one came from, as the car originally came with a Marina carb and Manifold. I think the Minor-esque one came in a box of bits.

Post by **Willie** » Mon Feb 23, 2004 7:36 pm

When I discovered the problem I sleeved the oversized filter
inlet down to 1/8" and have had no 'oily filter' problems since.

Post by **Peetee** » Mon Feb 23, 2004 7:41 pm

IIRC you must have a closed circuit system if the car is designed to have one. there is a safety issue concerned with this. It's quite possible for quite high pressures to occur if the system is closed or blocked - especially crankcase breathers. my friend was driving his Escort with a blocked breather when the oil filler cap blew off and hit the bonnet so hard he heard it at 70mph on the motorway!
A healthy engine should not have too much oil vaporisation anyway. Another reason to have a vent is to release the condensation that builds in the engine - especially in cars doing short journeys.

Post by **Gareth** » Mon Feb 23, 2004 7:44 pm

That sounds about right. I've got a book that gives diagrams on all the possibilities (circa 1973 or so) for crankcase breathers, but still don't really understand which arrows are going where...

Morris Minor Owners Club

Rocker cover breather

Rocker cover breather

oil in filter

filter