Morris Minor Owners Club

I recently acquired a cam follower cover with oil trap to fit to my '68 Minor so I can connect a breather from this to the air filter. Whilst removing the attractive yellow paint I noticed that the mesh in the filter can was disintegrating as can be seen in the photo. I'm concerned what bits of this would do to my engine if fitted like this, so I'll be removing it. Question is what best to replace the mesh with, and a warning to others to check this before fitting second hand parts.

Gavin,

The original filter inside the oil trap was steel mesh, and relied on oily fumes to stop it rusting and disintegrating! It looks like yours has done just that and needs to be thoroughly cleared out from the canister. Ideally it should be replaced - a 'Brillo' pad is an excellent replacement.

The oil separator is part of the later 'closed circuit' crankcase ventilation system, and is not connected to the air filter in any way. The crankcase oil fumes must NOT pass through the air filter element, they will just clog it up.

The early crankcase breather design was for air to flow FROM the air filter into the rocker cover, and OUT through the 'draft' tube attached to the front tappet cover. The oil filler cap was 'non-vented'. It relied on forward movement of the car to create the 'draft', and more often on older engines just clogged up the air filter with fumes flowing in the wrong direction.

The 'closed circuit' system takes air IN from the 'vented' oil filler cap, down through the crankcase, though the oil separator and up to the PCV valve fitted to the inlet manifold and finally is ingested by the engine itself. There is no connection to the air filter in any of the 'closed circuit' systems.

When was the change made to the 'closed circuit' system?

The diagram below shows some of the 'closed circuit' details:Are you proposing to fit the complete 'closed circuit' system?

This is a common problem with these type of breathers and which creeps up on you unawares.
You must remove all the remains of the gauze including the clips holding the gauze in place and replace the old gauze with stainless steel pan scourers which are of virtually the same form as originally used i.e. spiral turnings.
If the clips are salvageable reuse to keep the pan scrubs in place.
Below is a photo of the remains of the gauze and clips which I posted some time ago to make people aware of the problem.
Note: A Brillo pad may contain soap/detergent and therefore if it does it should not be used. The soap/detergent can drain back into the engine.
The stainless steel scouring pads do not contain any soap/detergent.

Can you disassemble these without cutting them open? I could not see a way to do this.

The only way to get the gauze out without cutting open the canister is by pressing a rod down through the top hole and hooking out the gauze using the large bottom hole. Not easy but attainable with patience. The same goes for fitting the replacement gauze.
The most important thing is to remove all of the all gauze and thoroughly wash out the canister to get rid of the crud.
If the task is considered too difficult you can always use a rear cam follower chest cover on the block front opening and replace the front timing chain cover with one that has the separator canister attached and which will attain the same result.
http://www.ebay.co.uk/itm/ORIGINAL-MINI ... SwdGFYtv2T

If you do not want to dismantle the front of the engine - you can always fit as I have done a breather canister to the unused fuel pump aperture (if provided) http://www.minispares.com/product/Class ... c/breather clutch housing.aspx|Back to search by the use of an adapter plate.
The breather canister on the fuel pump aperture serves exactly the same purpose as one fitted to the cam follower chest cover and timing chain cover and can be connected to the breather valve on the manifold (if fitted) in the normal way.

Thanks for all the replies. My car is currently fitted with twin SUs which i am replacing with an AUD13 which i am in the process of refurbishing. The car also has servo brakes fitted, and i am modifying a 'thick' carb spacer to provide the vacuum connection for the brake servo. i was considering providing two connections on this modified spacer, the second which i would connect to the cam follower breather, which along with a vented oil filler cap on the rocker cover would provide negative pressure in the crankcase which i understands helps reduce oil leaks from the rear engine seal. Would this be acceptable? Any risk of oil vapour ending up in the servo, i assume not if the gauze filter is doing its job?

To answer Islipminors question, i hadn't considered fitting a PCV valve as i don't have one ( and understand they are hard to come by?), and the manifold i've acquired doesn't have a connection for this. i assumed the above solution would be similar, albeit without the control a PCV would provide.

I followed Phil's excellent advice at the time-just did it slightly differently.
I then fitted a flame trap from a Land Rover.
http://www.ebay.co.uk/itm/LR-DEFENDER-3 ... Sw7GRZDHb6

Regards
Declan

Looking at the canister has anyone ever changed the top to create a screw in lid?

If you could routinely remove and inspect you could ensure it was always functioning correctly. This could be done if the top section could be made to have a connection with a screw thread

Looking at the canister has anyone ever changed the top to create a screw in lid?

If you could routinely remove and inspect you could ensure it was always functioning correctly. This could be done if the top section could be made to have a connection with a screw thread

A very good idea.
The modified canister I would suggest should be based be a new one as not only the gauze disintegrates but the body of the canister rusts through from the inside. I have several that when cleaned up were found to have pin holes in them.
I have a new canister/separator with which I will investigate the possibilities.

I also found a rusty mess inside the breather so i cleaned it out and left it to soak in a citric acid powder mix for a few days then i dipped it in zinc primer and when it dried i pushed stainless steel wire wool in which was a scotch brite 3M pad, seems to be holding up ok.

albeit without the control a PCV would provide

The PCV valve is essential. Without it, a straight connection to the inlet manifold, or a sandwich plate, will create MUCH too much vacuum!

An AUD13 is a standard 1.25" SU I think? Why are you replacing twin SU's with a small single one?

The alternative to a PCV is it use an SU carburettor with the crankcase vent port on it, then the tube from the oil separator does connect directly to it, with no need for a PCV.

IslipMinor wrote:

albeit without the control a PCV would provide

The PCV valve is essential. Without it, a straight connection to the inlet manifold, or a sandwich plate, will create MUCH too much vacuum!

Exactly. I have temporarily installed an original Smiths PCV valve on my MG TD and I have two 1.5mm restrictors in each line to both sides of the inlet manifold (Silicon & PVC tubes). The vacuum measured at the inlet manifold at idle was 0.9bar which is much too high. I tried various restrictors but 1.5 gives the best idle.
It practically eliminates the oil leak from the non existent rear scroll. I have measured a crankcase pressure of -120mm water gauge.
I can now plumb it in permanently.
Regards
Declan

The AUD SU carb is indeed a 1 1/4" SU carb.

http://sucarb.co.uk/carbspec/carburetto ... s/id/1907/

I have to agree that used pcv valve are not readily available but they do come up for sale on 'e' bay on a regular basis.
http://www.ebay.co.uk/itm/Mini-Mk1-PCV- ... Sw40pZdNq4

They are available new from MOSS
http://www.moss-europe.co.uk/valve-asse ... soc=515715

The last one I bought was for my Landrover it was new and cost just over £70.
Spares are available for the valve on 'e' bay if you have the valve body.
http://www.ebay.co.uk/itm/Mini-Cooper-S ... SwwE5WWJXO

http://www.ebay.co.uk/itm/Mini-Cooper-S ... SwnipWWJUt

http://www.ebay.co.uk/itm/Mini-Cooper-S ... xypNtSilqN

http://www.ebay.co.uk/itm/Mini-Cooper-S ... SwAKxWWJbJ

Phil,
Here's a source for the PCV valve at a good price. Leacy Classics are really good and their postal charges are humane-free delivery to EU above £60 which is very attractive.
http://www.leacyclassics.com/13h5191.html

Regards
Declan

Declan
That is a good price.
Phil

I struck lucky at the national, bought an exhaust/ inlet manifold for a fiver, solely for the attached PCV valve.

For the price of a PCV, you could look at getting a complete SU HIF38 and manifold, which comes as standard with the tapping for the servo connection and the crankcase breather ventilation port on the HIF38, so no need for the PCV, all for a similar cost?

This one sold on eBay recently for £60:
http://www.ebay.co.uk/itm/classic-mini- ... Sw42JZAjpq

You would need an air filter, but then sell the twin SU's and make a profit!

Ok, so connecting the breather between the carb and manifold is not the same as connecting it into the connection on a carburettor, where the connection is up stream of the butterfly valve, so the depression is less than at the manifold I assume. All food for thought.

Islipminor, to answer your question, the car came with a cherry bomb exhaust and twin SUs fitted to a standard 1098 engine. The car is to be my wife's daily drive, and she didn't like the noise, so I've fitted a standard exhaust, and so there is no real point having twin SUs. Also we'd like to get the engine back to something like original, and the SUs will probably end up on my 1275 Midget which currently has a HIF44.