Crankcase Breathing
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Re: Crankcase Breathing
I sent a message to the guy on here who was doing a tappet chest breather/chimney can modification but I've not heard back from him yet. If he doesn't do it any longer then I have been thinking about having a go at it, unless some other company has picked up the baton with it? Anyone know?
It's seems like a real weak point and the photos of the inside of some old cruddy canisters he posted support that.
Look at this one. There is a chimney on the timing cover and the tappet chest and a PCV valve.

It's seems like a real weak point and the photos of the inside of some old cruddy canisters he posted support that.
Look at this one. There is a chimney on the timing cover and the tappet chest and a PCV valve.


1961 Morris Minor 948
1970 Morris Minor 1098
1970 Morris Minor 1098
Re: Crankcase Breathing
That seems like a real belt and braces job!
I would have thought that if your separator is mounted on a tappet chest cover it would be an easy matter to remove it and flush it out every so often. It is for that reason I am getting rid of my Midget timing chain cover mounted one and attaching one to the (redundant) mechanical fuel pump flange, as did Philthehill on one of his engines.
I have an old PCV in my parts box, by the way. Is it worth repairing and reusing it?
I would have thought that if your separator is mounted on a tappet chest cover it would be an easy matter to remove it and flush it out every so often. It is for that reason I am getting rid of my Midget timing chain cover mounted one and attaching one to the (redundant) mechanical fuel pump flange, as did Philthehill on one of his engines.
I have an old PCV in my parts box, by the way. Is it worth repairing and reusing it?
Re: Crankcase Breathing
Roughly how much is a 2nd hand complete manifold (with a vacuum flange on the inlet) worth?
Yes, everything is worth what someone is willing to pay for it but I've seen one for sale and although I don't need it, I might like to fit a PCV valve in the future if it will prevent oil leaking.
Yes, everything is worth what someone is willing to pay for it but I've seen one for sale and although I don't need it, I might like to fit a PCV valve in the future if it will prevent oil leaking.
Last edited by rocco on Thu Sep 26, 2024 8:31 am, edited 1 time in total.
1961 Morris Minor 948
1970 Morris Minor 1098
1970 Morris Minor 1098
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- Minor Maniac
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Re: Crankcase Breathing
The canister and its internal gauze was never meant to last as long as some have done.
Re: Crankcase Breathing
Rocco, I too have a similar manifold for a PCV valve, thinking if I fitted it, it would help solve the slight oil leak I’m experiencing, however reading various posts, I’m now not so sure that outcome would be achieved ?
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Re: Crankcase Breathing
Les
As I have pointed out before the PCV valve was a legislative requirement (especially for the American market) not a mechanical requirement. The 'A' Series in good condition does not need the PCV valve.
Phil
As I have pointed out before the PCV valve was a legislative requirement (especially for the American market) not a mechanical requirement. The 'A' Series in good condition does not need the PCV valve.
Phil
- svenedin
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Re: Crankcase Breathing
Gentlemen,
IF you want to install a PCV valve you need the correct manifold. This needs to have the threaded inlet for the PCV valve spigot AND a smaller threaded hole for the stud or machine screw to attach the PCV valve steady bracket.
I am only interested in PCV valves because my car had one as original from the factory which is a rarity in Morris Minors. In theory it is a superior breathing system to earlier systems.
Any breathing system, no matter how good will be overwhelmed by excessive blow-by in an engine with worn bores and/or worn piston rings. So a PCV valve is by no means a silver bullet. For want of a more elegant way of putting it, the PCV has a significant advantage in that it is designed to maintain a steady small vacuum regardless of what the engine is doing. None of the other systems can do this.
If you already have all of the parts then it is just a matter of an hour's work and some new gaskets to fit a PCV valve. In such circumstances it is worth a punt I would suggest.
Here is a top photo of the correct manifold 12A1097 and a diagram showing the various parts (diagram is from a Mini but is the same as the Minor set up). Sorry my bare feet show in the photo!!
https://www.somerfordmini.co.uk/catalog ... 774_100817 (see the drawing marked Manual Gearbox)
IF you want to install a PCV valve you need the correct manifold. This needs to have the threaded inlet for the PCV valve spigot AND a smaller threaded hole for the stud or machine screw to attach the PCV valve steady bracket.
I am only interested in PCV valves because my car had one as original from the factory which is a rarity in Morris Minors. In theory it is a superior breathing system to earlier systems.
Any breathing system, no matter how good will be overwhelmed by excessive blow-by in an engine with worn bores and/or worn piston rings. So a PCV valve is by no means a silver bullet. For want of a more elegant way of putting it, the PCV has a significant advantage in that it is designed to maintain a steady small vacuum regardless of what the engine is doing. None of the other systems can do this.
If you already have all of the parts then it is just a matter of an hour's work and some new gaskets to fit a PCV valve. In such circumstances it is worth a punt I would suggest.
Here is a top photo of the correct manifold 12A1097 and a diagram showing the various parts (diagram is from a Mini but is the same as the Minor set up). Sorry my bare feet show in the photo!!
https://www.somerfordmini.co.uk/catalog ... 774_100817 (see the drawing marked Manual Gearbox)
Last edited by svenedin on Thu Sep 26, 2024 7:35 pm, edited 1 time in total.
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Stephen
Stephen
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Re: Crankcase Breathing
I can see you like to live dangerously, Stephen - imagine if you had dropped it on your toes! 

Re: Crankcase Breathing
Phil, I always read your posts with interest and accept the function of the PCV valve as you’ve pointed out. The engine that came with my van was a recently bought gold seal, so after the restoration I naively fitted it, accepting it to be good. However it has always had this annoying leak, not bad but annoying, and initially thought, amongst this valves main function, it might have some influence on this leak, pulling a better vacuum. One could be excused for thinking this a short cut to rebuilding the engine ———and one would probably be right !! ———-but for the time being, I’ve had enough for a while !
- Bill_qaz
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Re: Crankcase Breathing
Les what level do you run the oil at?
When I first got mine I kept it topped up near max as it came with leaks. After sorting the rocker gasket it was predominantly from bell housing, rear scroll but I read a tip on keeping level lower between min and max and since doing so the drips have noticeably diminished and top up is required less frequent. My 1098 is just the wind pipe breather and pipe from rocker cover to air filter no cannister or pcv.
Worth a try
When I first got mine I kept it topped up near max as it came with leaks. After sorting the rocker gasket it was predominantly from bell housing, rear scroll but I read a tip on keeping level lower between min and max and since doing so the drips have noticeably diminished and top up is required less frequent. My 1098 is just the wind pipe breather and pipe from rocker cover to air filter no cannister or pcv.
Worth a try
Regards Bill
Re: Crankcase Breathing
Thanks for that Bill, that’s well worth trying, I top up to max but yes anything between the high and low mark is apparently designated acceptable.
Re: Crankcase Breathing
Baritone UKe
Which vacuum pump did you use please.
Regards Win
Which vacuum pump did you use please.
Regards Win

South Yorkshire
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Re: Crankcase Breathing
Thanks for the suggestion, I tried that first. Not received any reply.
Regards Win
Regards Win

South Yorkshire