Morris Minor Owners Club

When I went to look at the '67 Minor I just bought the PCV valve was bleeding so much air into the manifold that the car would barely run. To do a test drive we blocked the fitting on the intake and rerouted the crankcase hose to the air cleaner. This got things mobile enough to make sure there were not too many other nasty surprises waiting for me.

I need a quick course on exactly how this valve is made, how it works and where I can get a replacement or suitable parts for it. I'd rather have it working to maintain a slight low pressure in the engine and avoid oil leaks through main seals.

Let's hear from the experts on this panel, I've been reviewing responses on all sorts of subjects and I'm sure this is the right place to ask the question.

BTW, if it makes any difference the car was built for the North American market so it may be different from UK specs.

Looking forward to lots of answers,

Darrell McDonald

I believe it can indeed be overhauled - and you are right to try to do so. I don't know how - but I'm sure it's not that difficult! You may need to make a new diaphragm for it. Take it to bits and let's see the inside of it!

hear is a link for you

http://en.wikipedia.org/wiki/PCV_valve

the PCV valve is not in use in the UK on minors
but i see no reason why you could not take it out
of the system and do it the normal English way
unless you have very tight testing of old cars

Henry

Hi Henry,
The English way is normal ??? Sorry, I couldn't resist that.

As the Wiki article explains a PCV actually reduces oil leaking from the engine which in all my former British cars has been "normal". I'd like this one not to embarrass me when I park it in a friend's drive.

Darrell

PCV valves were indeed fitted to Minors in 'England' and several other UK countries. The idea is excellent - suction on the crankcase is essential to prevent oil leaks. However - it can be done without the PCV valve if needs be.

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The breather control valve fitted to my Traveller as the carbs have no breather pipes. Normally fitted on American spec MG Midgets according to Haynes Manual. It comes apart by removing the spring clip, taking care not to lose the inside spring.
The only maintenance is to inspect the rubber diaphram and clean the emulsion which accumulates on short runs

Thank you for the pictures Mike, that is the very valve I'm talking about. I sure hope there is still a spring in it. I did find a supplier with a replacement diaphragm that I have ordered. If the spring is missing I will have to buy a whole valve. I see a few of them on eBay but they are $40+.

Hmmm, I wonder if I can get one of those to work on my old MM?????

Darrell

I'm sure if the spring is missing - you can easily enough adapt something to fit!

Hmmm, I wonder if I can get one of those to work on my old MM?????

Darrell[/quote]
I would not bother. You should just have a pipe from the tappet chest, attached to an engine/gearbox bolt and ending alongside the gearbox. Items 57 - 64 on engine diagram in workshop manual

East Sussex Minors sell the valve for £24, part number FUL 144, or so they tell me. Also the diaphragm is available (not sure where I saw it though; it's one of the interweb sellers)

I just did the connection without the expensive valve - 1/8" dia hole into the inlet manifold. Yes - it upsets the idle slightly - but with a full race cam - the idle wasn't great anyway! It certainly eliminated leaks and fumes very nicely.

The other aspect which may need attention is in the control of air into the engine. I couldn't get tickover below 1200rpm when I first had the car (I was told this was due to the mildly hot road cam fitted). After much work looking for an air leak into the manifol, including a fitting of the Fish carb and replacing the manifold, I discovered that some bright spark had butchered the air bleed hole in the oil filler cap. They had used a screwdriver and there was a ragged aperture equivalent to about 1/4" diameter. I fixed this and reduced the hole to .7mm. The tickover settled immediately, also the response from low revs by the SU carb. In addition the fuel consumption improved.
I am so enthused that I shall now try re-fitting the Fish, which gave a real performance boost at higher revs. The problems with the first trial resulted from the engine breather, from the chain case, was going into the manifold downstream of the carb, as compared to the SU in which it connects into the carb around the venturi. If I refit the Fish I shall also install a suction control valve as it restricts the suck at higher manifold suction, during tickover, and during initial acceleration.

The outcome is that I did find a replacement diaphragm, not even expensive, and now that I finally have the car home it took about 20 minutes to fit the part and reroute the hoses. That included removing the valve to clean it up. It looks to me like the same valve is used on many different cars but the diaphragm and the basic part are the same. Changing the strength of the spring and the size of the orifice would be the only requirements for other cars.

Short story: it runs a treat now, tick-over settled right down and removing the oil filler cap will almost stall the engine.

Darrell McDonald

Great success!