16 replies to this topic

[ucchockey]

Should the breather cap on the rocker cover be emitting steam? I've read they should be pulling air into the crankcase not emitting fumes.

[Ellie]

Is the breather blocked? Does it feel a bit spongy? If so, take it off and clean it out. Mine did at high revs, I was watching it on the rolling road.

[69k1100]

Generally speaking breathers vent crank case pressure to the atmosphere. They don't suck air in.

[ucchockey]

Does what feel spongy?
The breathers may be blocked but I can only look into the end of breather on the bell housing. The other one is hidden round the back.
What's the best way of cleaning breather canisters?

[1968andyf]

To clean them you need to remove them and wash out with a parts wash. Do you get a creamy white gunk in the cap or rocker cover it could just be condensation if so give the car a good run to clean it out . The other thing it could be is breathing caused by piston blow by from a worn engine

[Ethel]

The filler cap is vented to allow air in. Ideally the hose connections to the induction system will suck a bit faster and reduce the crank case pressure.

 

This can be a sign of a failed head gasket, but burning petrol also produces water so don't jump to that conclusion.

[ucchockey]

I've got a bit of mayo in the rocker and on the lid yes.
The car doesn't get much use and is mainly short journeys so I think it is condensation.
The other breathers aren't connected to the carb. The oil and water aren't going down so I don't reckon it's the head gasket. The oil is golden colour and the antifreeze is pink so all good there. I'll just do an oil change and keep an eye on it I think.

[Rog46]

The cap should draw air in whilst the engine is running if all the breather pipes to the carb are clear. However once the engine is off its likely that warm oil vapour rising in the engine might escape from the cap.

Is it "steaming" whilst the engine is running or after when you shut it off and it's hot?

[Ethel]

It is worth plumbing up the breathers, that oil change will last longer if the blow-by fumes have been diluted with fresh air. It would also clear most of the condensation.

 

Pink freeze may not be the most Mini friendly, unless it's a late model with a better sealed cooling system.

[Mini Manannán]

It is worth plumbing up the breathers, that oil change will last longer if the blow-by fumes have been diluted with fresh air. It would also clear most of the condensation.

 

Pink freeze may not be the most Mini friendly, unless it's a late model with a better sealed cooling system.

 

Pink freeze? 

[ucchockey]

It steams when it's running.
Some people say the cap is to vent fumes out and others say it's to draw air in. Which is it 😕

Will plumbing in the breathers effect the mixture in the carbs? I'm running twin hs4 carbs so which one do they go to? Or is it one to each carb?

Edited by ucchockey, 20 February 2015 - 07:43 PM.

[Rog46]

If you don't have breather pipes connected to the carb, then it's to relieve pressure as the engine warm's up. Without it relieving the pressure, oil will get blown out past the rear oil seal! So what you are seeing is any water being boiled off especially if it's only used for short runs and condensation can build up.

Connect the breather to the carb. This scavenges these vapours from the engine and keeps the internal pressure down and reduces the risk of oil being blown past the oil seals. The cap will then allow any excess air needed to be drawn in.

So to answer your question both are right! Breathers connected = air in, no breathers connected = fumes out

Edited by Rog46, 21 February 2015 - 11:23 AM.

[Ethel]

That's probably why they were disconnected. Twin carb cars had a restricter valve to connect the breathers to the manifold, or just fed to the air filter housing. They shouldn't make much difference to the engine tune as their flow  is negligible against an open throttle. 

[ucchockey]

The twins were added by me and are certainly not original. I'll connnect the breathers up then. What's the worst that can happen? 😃 Should I do both breathers to one carb with a T connector or one breather to each carb?

[Dan]

Both breathers to both carbs with two Tee pieces (or Y pieces are actually easier), you should get a pair of genuine breather hoses to use as the emissions ports on the carbs are a different size than the breather outlets and the genuine hoses are tapered for this.

If the carbs have emissions ports then a PCV valve is not needed.