19 replies to this topic

[ltdaigle]

Hello,

 

I have a 1989 Austin Mini Mayfair and it recently started smoking.  It's not a lot but enough to see and worry about.  I located where it is coming from but not sure what it is or why it is smoking.  I know a little about cars and thought it was a charcoal canister with a filter on the end but it connects to the back of the engine and I didn't think that was where they connected to.  Anyway I have some pictures here with the part that is the problem circled.  I was wondering what it is, why is it smoking and is it fixable or just replaceable.  I didn't want to start pulling it off without knowing in case stuff starts flowing out or something.  Thanks for your time with my ignorance.

 

Lance

 

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[KernowCooper]

Its a mod by the previous owner to put a filter onto the Crankcase breather that used to be connected to the intake manifold, if its smoking as you call it more it indicates a bit of engine wear, not generally a good sign, in standard trim the fumes would have been recycled into the inlet manifold, I see yours has a aftermarket airfilter and there is a breather pipe blocked off with a screw on the carb above the fuel pipe inlet that could be used to recycle the fumes, but it could well upset the idle doing it if the fumes are bad

Edited by KernowCooper, 18 November 2015 - 11:34 PM.

[nicklouse]

First things first is it smoking of steaming?

As above if is a filter that has been added to one of the engine breathers, these are originally connected to a port on the carb.

Water vapour is often seen coming out of the breathers and can also manifest itself under the oil cap as a white emulsion.


So smoke or water vapour with a hint of oil?

[sledgehammer]

I would take it off & reconnect it to the carb as it should be

 

if it is breathing heavy from the pipe then it is an indication of a worn engine , but may be just steam / slight blow by

 

these filters seem to be trendy at the moment , but if fitted in that way , it means the gasses from the sump arn't being properly dealt with

 

it can lead to the oil ageing quickly / being contaminated 

 

what is the oil like ?

[spiguy]

not to mention oily vapours building up in the engine bay, and probably finding their way into the cabin, not the best for your health if that does happen.

Edited by spiguy, 19 November 2015 - 12:08 AM.

[Steve220]

If the engine is up to temperature then what you are seeing is most likely to be oil vapour. Before that, it maybe steam, as mentioned above.

 

Personally i'd either plumb it back in or into a catch can.

[Ivor Badger]

Breather not connected to negative pressure inlet manifold = increased crankcase pressure and less fumes removed = increased ring wear = increased fumes in crankcase = more fumes from breather ad infinitum.

[ltdaigle]

Thank you for all the quick responses.  I'm going to try to give an answer to all and ask more.  The smoke is not a lot and it's kind of off white color but it does smell like oil and the little filter on top has some oil in it.  The oil in the engine is good and clean.  How would I go about connecting it back to the manifold?  If I disconnect it from where it is now is there a piece to cover that back up?  Yes it does smell of vapors in the cabin which I thought was an exhaust leak but I fixed that and it's not as bad but still smells.  I would really like to fix it back if possible.  Thanks again for all your help.  Looking forward for more information.

[limby2000]

Change it to non-smoking!

[HUBBA.HUBBA]

I'd say it depends on the spec of you engine. If its a high power motor then id say your bound to get more crank case pressure thus pushing more crap out. But saying that your carb looks like an older type su so you probaby not producing too many bananas

[Keith Staley]

How would I go about connecting it back to the manifold?  If I disconnect it from where it is now is there a piece to cover that back up?  Yes it does smell of vapors in the cabin which I thought was an exhaust leak but I fixed that and it's not as bad but still smells.  I would really like to fix it back if possible.  Thanks again for all your help.  Looking forward for more information.

 

Have a look at the left side of the carb, there looks to be a black pipe that has been blanked off?

 

To restore it back to original, you'd need to remove that pipe and also the chrome filter that you're talking about and connect the two with one of these that loops around the back of the carb. As the others have said, the harmful emissions will then come out of the crankcase and get fed into the carb which then gets burnt by the engine to render them a lot safer.  

 

[ltdaigle]

Thanks Kieth...I'm going to try this out.  Since there is oil build up on the filter and the inside of that piece has a lot of build up, can I and should I replace it or have something in place so oil build up doesn't travel to the carb.  Not sure what piece to look up to replace.  Thought it was a charcoal canister but it doesn't look anything like the ones that I look up.  Thanks again

[ltdaigle]

Thanks again to everybody.  I found all the parts.  Should I replace the tappet cover with breather or can I continue to use the one currently on there?  What is inside and can I clean it or renew it?

[Wim Fournier]

Well, I 'll try and tell the story in other words:

When the inlet gas is burned after the spark has come from the sparkplug, the piston goes down. The piston rings are trying their best to seal the piston against the cilinder wall. But still there is passing a bit of burnt gas between piston and cilinderwall into the crankcase. (Blow by).

So, when the ingenieers had not done anything to that, the pressure in the crankcase would build up. So, they arranged a crankcase ventilation system. Behind the engine -on the tappet case- they made an cannister where the burnt gasses can come out of the crankcase. To avoid that too much oil comes with these gasses, they made a separator.

To get a 'positive crankscase ventilation' they putted a tube on top of the separator and connected this to the foot of the carburettor, so that the light vacuüm -that is ther- should suck the burnt gasses out of the crankcase. With a little depression in the crankcase the oil has more difficulty to get passed the oil seals on the crank, as well.

As said above, people who do not understand this system put an filter on the end of the tube, like they have seen on pictures of racing cars. The filter is ment to withstand dust to get into the drankcase. Point is namely that those race guys use the suction that is in the inlet manifold, that is a lot stronger than at the foot of the carburettor, to ventilate the crankcase.

The 'smoke' that you saw coming out of the filter is partly waterdamp. When you burn fuel, a part of the 'smoke' is water. You have seen that on cold mornings after starting your engine, the exhaust is spelling 'white smoke' (waterdamp). As soon as the exhaust is getting hot, the waterdamp does not condensate immediately, so that the smoke becomes colorless. When this waterdamp from the blow by remains in the crankcase it emulgates with the oil and forms white or black suldge as you can find inside the rockerbox of your car when you only drive short distanties, where by the engine does not come on 'working temperature'.

[Dusky]

As said above, people who do not understand this system put an filter on the end of the tube, like they have seen on pictures of racing cars. The filter is ment to withstand dust to get into the drankcase. Point is namely that those race guys use the suction that is in the inlet manifold, that is a lot stronger than at the foot of the carburettor, to ventilate the crankcase.

Most racers Ive seen use a catch tank.( its even mandatory) Inlet manifold suction tends to suck pure oil into the manifold, a common problem with weber conversions.

I vent my 2 breather via a pipeand filter under the wings, oily fumes should protect against rust :)

Edited by Dusky, 19 November 2015 - 06:29 PM.