32 replies to this topic

[Steve-O 2014]

The breather on our mini is currently just going to a small filter, should I remove this and connect it to the carb? Is there any gains to having it go to a filter? 

 

 

[Gremlin]

No real gainsas such, the filter is ok as is plumbing it into the carb, search around on this forum and make up your mind, if you still can't decide I would personally say plumb it into your carb, seals last longer, and your MOT man is happyier, less chance of leaks apearing as well

[Dan]

 Pub points!

 

  Yes it's much better for the engine (and everyone's health, your wallet and your free time) to hook it up to the carb.  You might have to do some retuning.

[Fispop]

It goes into the filter so any particals don't go into the cylinder head (trapped by the filter, if you remove it you take the risk of crank case compression, the idea is that the presure in the engine is sucked out. This is very important on old cars.

To put it into the car it is best to add an additional filter (inline).

Removing it WILL cause oil leaks.

[Minigirl]

Could this cause oil to leak past the clutch oil seal as we are getting that badly. Plus oil leaks from other places 

 

 

 

 

Would timing and fuel need re adjusted ?

[Gremlin]

It goes into the filter so any particals don't go into the cylinder head (trapped by the filter, if you remove it you take the risk of crank case compression

I don't quite get what your saying, can you elaborate?

[zerobelow]

So, my understanding on the topic:

 

It is a breather for gasses in the crank case. There definitely needs to be a vent of some sort. Also, you don't want anything going back into the crank case, so at the minimum, there needs to be a filter. The normal condition is that it plumbs into the carburetor, which will provide a small bit of negative pressure to suck out any gasses from there.

 

The pros for connecting it to the carb: It meets the emissions requirements for most places (here in the states, that's required for any post 1957 car), I've heard it's required for MOT in the UK as well. Also, it's arguably healthier for the engine to have some suction to remove any potentially combustible fumes from the crank case, and it is supposed to help some of the seals.

 

Pros for venting it through a filter: It's possibly simpler, especially if you have a carb that doesn't have a connection for that (ex: a weber 45). Also, some people complain that the oil from the crankcase vent will, over time, leave crud inside the carb, making it need cleaning more often. And, connecting it to the carb may affect engine tuning if it wasn't previously connected.

 

My engine builder here recommends plumbing the vents to a catch can, then venting the catch can to atmosphere, which is effectively similar to venting through a filter. My weber 45 doesn't have a port to accommodate PCV. 

[Fispop]

Could this cause oil to leak past the clutch oil seal as we are getting that badly. Plus oil leaks from other places 
 
 
 
 
Would timing and fuel need re adjusted ?

Pistons traveling ant up to 8,500 revelations per second will create a compression in the gearbox area which is where most of the gaskets and oil seals are including to the clutch. When you get a build up of presure it must escape from somewhere (weakest link).

The idea behind the pipe going from the engine to the carburettor is, as the engine sucks air into the cylinder head and mix's it to the fuel it sucks the air from the engine, so releasing the presure, think of it as a balloon a build up of air wants to escape but where can it go. There is only a smallish pipe for the air to go out of the engine and this is not enough so I also need to be sucked out, the carburettor sucks this air relieving the presure.

If the weakest seel is to the clutch the presure will push the oil there if the weakest seel is to the drive shafts the oil will pe pressurised out there, not a lot of importance is paid to this little pipe but it does a big duty, otherwise why would it be there.

Prior to it going into the carburettor, cars had a pipe leading to the bottom of the car and the presure was sucked from a down draft, this caused oil deposits on the roads and conciquently stopped.

This does not mean that if you have a leak to clutch or drive shafts this could also be to wear and tear but it will not help.

This will not effect the timing but a very slight adjustment to the carburettor, but if the carburettor has never been messed with it will already be adjusted to this. Carburettors also wear, this is one of the joys of Minis, the list goes on and on.

Hope this is of help!

[Fispop]

It goes into the filter so any particals don't go into the cylinder head (trapped by the filter, if you remove it you take the risk of crank case compression, the idea is that the presure in the engine is sucked out. This is very important on old cars.
To put it into the car it is best to add an additional filter (inline).
Removing it WILL cause oil leaks.

You can put the pipe directly to the carburettor if it has an inlet pipe but it is very much advised to put an inline filter to catch any oil or deposits from the engine/gearbox.

[Dan]

If you have a breather canister rather than just a pipe outlet on the engine, just connect it up.

[Captain Mainwaring]

 

Could this cause oil to leak past the clutch oil seal as we are getting that badly. Plus oil leaks from other places 
 
 
 
 
Would timing and fuel need re adjusted ?

Pistons traveling ant up to 8,500 revelations per second will create a compression in the gearbox area which is where most of the gaskets and oil seals are including to the clutch. When you get a build up of presure it must escape from somewhere (weakest link).

The idea behind the pipe going from the engine to the carburettor is, as the engine sucks air into the cylinder head and mix's it to the fuel it sucks the air from the engine, so releasing the presure, think of it as a balloon a build up of air wants to escape but where can it go. There is only a smallish pipe for the air to go out of the engine and this is not enough so I also need to be sucked out, the carburettor sucks this air relieving the presure.

If the weakest seel is to the clutch the presure will push the oil there if the weakest seel is to the drive shafts the oil will pe pressurised out there, not a lot of importance is paid to this little pipe but it does a big duty, otherwise why would it be there.

Prior to it going into the carburettor, cars had a pipe leading to the bottom of the car and the presure was sucked from a down draft, this caused oil deposits on the roads and conciquently stopped.

This does not mean that if you have a leak to clutch or drive shafts this could also be to wear and tear but it will not help.

This will not effect the timing but a very slight adjustment to the carburettor, but if the carburettor has never been messed with it will already be adjusted to this. Carburettors also wear, this is one of the joys of Minis, the list goes on and on.

Hope this is of help!

 

 

 

Think about that again (notwithstanding the typo about speed - I know what you meant)....they will on a triumph twin but not on a mini

Edited by Captain Mainwaring, 29 May 2014 - 12:20 PM.

[Gremlin]

Don't just re think about the speed the pistons don't pump the air in the crank case, sure it moves the air about but doesn't pump it, theres no valves

[Fispop]

A piston is forced down from the igniting of the fuel air mixture, that's where the presure is built up from.

[Gremlin]

But the crank case is only pressurised by blowby, not by the piston moving

[CityEPete]

If its full to the brim from blow by and a piston comes down on a suck stroke it will increase the crankcase pressure, some air will try to go up the cylinders on squeeze and blow but the opposing cylinder to the one sucking is on its bang stroke creating even more pressure from blow by. If my laymans understanding is correct?