Crankcase breather pipe

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Mitchelljburgess1
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Crankcase breather pipe

Post by Mitchelljburgess1 »

Hi guys,
First post here and very excited to get some help with this head scratcher of an issue!
So I have a 57 model Morris Minor 1000
And I'm trying to get it running better, before I tune the timing and all I first need to find the problem with a hose coming from the carby not connected to anything. I have looked at a few diagrams and have found it most likely to be the crankcase breather pipe, I also feel suction from the tube and if I block it the engine slowly dies and stalls.
There are no ports for the hose to go on the rocker cover or block that I can find.
There is one hose from the rocker cover going to the intake at the filter on top of the carby and another hose running to the vacuum hydraulic brakes.
I'm in Australia if that helps model differences

In this photo you'll see the opening.[frame]Image[/frame]

It's a brass coloured outlet
Hose is not attached
Vernon
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Re: Crankcase breather pipe

Post by Vernon »

I think you are right, the port on the carb is for the later crankcase breather with a mesh filled canister attached to the front tappet chest cover. You might have the earlier open crankcase breather pointing down the side of the engine to air.
Mitchelljburgess1
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Re: Crankcase breather pipe

Post by Mitchelljburgess1 »

So do you suggest the reason the engine is running rough is not caused by this?
A random vacuum seems a little strange is all
Vernon
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Re: Crankcase breather pipe

Post by Vernon »

If you have the open to air crankcase breather you don't need the vacuum port on the carb so you could block it off and see if that improves the running.
bmcecosse
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Re: Crankcase breather pipe

Post by bmcecosse »

Put the tube from the breather on the port on the carb - not to the filter. And get rid of that fuel filter......
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IslipMinor
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Re: Crankcase breather pipe

Post by IslipMinor »

Mitchell,

Judging from previous posts on this topic, it has every chance of opening a real can of worms! You will get very bored trawling back through the archives.

From what you describe, you have the original 1957 crankcase ventilation system of an open 'draw' tube running down from the front tappet cover and a hose running from the rocker cover to the air cleaner?

The design is that when the car is moving forwards, air passes across the end of the 'draw' tube and sucks the fumes out of the crankcase, into the atmosphere/all over the underside of the car, with fresh air coming from the air filter into the rocker cover to provide a 'through' ventilation. It should have a 'non-vented' oil filler cap in the rocker cover, as the source of fresh air is from the air cleaner. It was not a great system, as the theory that air flowed FROM the air cleaner TO the rocker cover was often reversed in practice, and the air filter element got plastered in oil fumes! Not a problem for the UK spec oil bath air cleaners of that era, but for dry paper, an early death.

The carburettor in the picture is a later design and is designed to connect to a mesh filled canister on the front tappet cover, instead of the open draw tube, no vent tube in the rocker cover AND a 'vented' oil filler cap, which is now the source of fresh air INTO the crankcase. It works well and is a 'closed' system, as the fumes are sucked through the rocker cover, crankcase and the tappet cover canister filter/oil separator, then directly into the engine via the carburettor port and ingested as part of the combustion process in exactly the same way as modern cars.

As a first step, assuming that the original system is in place, and the hose from the air filter to the rocker cover is good, then block off the crankcase ventilation port on the carburettor and adjust the mixture to compensate for the changed air flow. It should run properly at this point - if not, then there is something else amiss.

Since you have an appropriate carburettor, it would be worth getting the later tappet cover & canister and vented filler cap to convert the crankcase breathing system into one that works - if you do, you will need to block off the rocker cover and air cleaner vents.
Richard


dudload
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Re: Crankcase breather pipe

Post by dudload »

Reviving this old thread. I noticed there was play in the throttle pin in the carb recently and fortunately came across a reconditioned carb with no play at an autojumble.

The problem is is that it has the later style breather, but I have the old style ventilation with tappet pipe and rocker cover to air filter. What's the best way to blank this off given it has a decent amount of suction?
philthehill
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Re: Crankcase breather pipe

Post by philthehill »

Put a suitable piece of rubber pipe over the brass stub and insert a suitable bolt into the open end of the rubber pipe.
You may have to change the needle in the carb to get the engine running correctly.
The correct needle for a 948cc engine is BX1 and for a 1098cc engine is AN.
Check the existing needle and change as necessary.

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