Breather question.

[67-2door]

My old 1968 minor had a breather pipe from the rocker cover to the air filter. The 1966 saloon I have now doesn't have a pipe from the rocker cover, just a bean tin shaped object on the side of the engine with a pipe coming off it to the air filter.
Should it have a breather from the rocker cover too? Do I need to do anything with the bean tin shaped object that breathes to the air filter (take it off & clean it out or anything?)
It does leak a little oil from the hole in the bell housing so I was wondering if inadequate breathing was to blame and if I should try to improve it?
Thanks.

[bmcecosse]

I prefer to have the rocker breather too - certainly doesn't do any harm. The later carb with a breather connection on the side does a better job of sucking away the fumes - without plastering the air filter with oil. Best of all is the later system that uses a flap valve on the inlet manifold to suck away the fumes....... this one - don't expect the price to stay low... http://www.ebay.co.uk/itm/Classic-Twin- ... 4ae833241b

[Declan_Burns]

You can use this one and it only cost £2.20.
http://www.ebay.co.uk/itm/370618181945? ... EBIDX%3AIT
I have it on the MG.
Regards
Declan[frame][/frame]

[67-2door]

As I don't have the right bits for a pcv type would it be an advantage to make sure my bean tin and hose are clear and also fit a rocker cover with a breather connected to the bean tin hose with a t-piece so that both the bean tin and rocker cover vent back into the air intake?
Thanks.

[bmcecosse]

Yes it would - but that £2 PCV (well done Declan - I had forgotten about that one you found in the past) is well worth buying - and then make an opening in to the inlet manifold - or even in the phenolic spacer between carb and manifold - and connect it there.

[67-2door]

The idea of drilling and tapping the inlet manifold is a little scary.
How does the pcv work? Would there be any advantage to fitting one inline between the bean tin/rocker cover and carb/air filter?
Thanks.
Neil.

[bmcecosse]

No - it gets the much better vacuum from the inlet manifold, but shuts when idling to preserve a nice smooth idle.

[67-2door]

I see, thanks.

[Declan_Burns]

Sorry, mistake on my behalf. The photo shows the flame trap for £2.20. The PCV valve (Ford pinto) is above it and was about £5.
Regards
Declan[frame][/frame]

[bmcecosse]

£5 ... gasp Do you have a link to it Declan ?

[Declan_Burns]

No Roy, it was quite a while back. Here's one for £4.50.
http://www.ebay.co.uk/itm/Jeep-CJ5-7-8- ... 35cd6c3fa9
Regards
Declan

[Theo_NL]

In my car the breather of the rocker cover is connected to the air filter, while the other breather is connected to the carb. Would it be wise to connect both to the carb?

[frame][/frame]

[bmcecosse]

I would just leave as is - unless it's plastering the paper filter with oil.....

[GBond]

In my car the breather of the rocker cover is connected to the air filter, while the other breather is connected to the carb. Would it be wise to connect both to the carb?

[frame][/frame]

My car came (from the factory, I believe) like yours but without the rocker cover breather, so the air filter connector is unused and there's just the side breather going to the carb.

This setup, at least in my car, needs some sort of restrictor or otherwise oil can get to the vaccuum chamber in the carb and cause the piston to stick, resulting in an awful running engine. I ended up making a restrictor with a 1/8" hole that goes inside the rubber tube and so far this has worked great; no fouling of the vaccuum chamber and far less oil usage than having just the side breather to the air filter. It's also easier this way to point the filter inlet upwards to try to get cooler air into the engine!

[bmcecosse]

Hmmm - I would worry about pressure pushing oil out the rear bearing onto the clutch!

[GBond]

Haven't had to even top off the oil in about 1800 km since connecting it with the restrictor to the breather on the carb. When connected to the oil filter I'd need to add oil about every 400 km so there's less oil coming out from the rear scroll.

The problem without the restrictor was that the carb breather has about a 1/4" inside diameter so it would actually have too much suction and the carb piston would get oil in it which would make it stick in place.

The car came from the factory with only one breather and so far it has been working great so for the moment the plan is to leave it as it is. I also don't use the car as much as many here do, if I did I'd probably also go for the PCV setup for the best possible reliability.

[IslipMinor]

The later 'closed circuit' crankcase system is designed to create a partial vacuum in the crankcase to reduce the risk of oil passing through the rear scroll and potentially on to the clutch.

The system uses a PCV valve screwed into the inlet manifold and a hose connected from the PCV valve to the front tappet cover. The oil filler cap must be the 'vented' type, as this allows a controlled amount of air to be drawn into the rocker cover/crankcase and any oil fumes drawn through to into the inlet manifold and burnt as part of the combustion process. The whole system will only work if it is complete.

Adding an extra hose from the rocker cover to the open air cleaner destroys any chance of creating a partial vacuum and so will not work as required. Even worse is that if the PCV valve, or side carburettor port is working, it will allow unfiltered air to be drawn from the air filer case into the engine via rocker cover. Even worse than that would be to fit a 'non-vented' oil filler cap to stop any fumes escaping from the rocker cover, because there is no crankcase vacuum!

It may not be the greatest of crankcase ventilation systems, but the best chance for success is to retain the standard design.

[bmcecosse]

I totally disagree with the leaky cap - NO modern engine has such a device, but they ALL have PCV valves. The leaky cap may work well enough on a pristine engine, but any wear soon results in an oily mess on the rocker cover - and oily/carcinogenic fumes in the cabin!

[IslipMinor]

Roy, Please explain how any sort of fumes and/or oil can come from the vented cap when the air flow is ONE WAY through the cap into the engine? If there is no vacuum being created, either because the PCV valve is not working or because the circuit is open to atmosphere is some way, the solution is to correct the problem of no vacuum, not stick an incorrect non-vented cap on.

The original closed circuit design works well, and does not require the engine to be in pristine condition; the whole point of the design to extract fumes from within the engine and prevent them from escaping into the engine compartment and/or the car itself. Why would you want to prevent the system from working correctly?

[bmcecosse]

Simply because the fumes generated overcome the 'vacuum' through the PCV valve.......which is only sucking through one pipe - the front cam follower chest pipe... I do think the PCV is the best system - but solid cap, and an additional breather from the rocker box. I repeat - NO modern has a leaky oil cap, but they do all have a PCV system. I'm guessing there is good reason.....