Breathing system?

[les]

Yep, it's been posted before but I'm only finding snipits here and there, using the search feature. What is the best breathing system to install on a 1098 engine, with an emphasis on parts required and pipework circuitry from where to where. Basically I want the best system to minimize oil leaks. Any advise please?

[IslipMinor]

Les,

I would suggest using the later 1098 closed circuit system. It uses the oil separator on the front tappet cover and a hose from that to the PCV fitted into the inlet manifold. No rocker cover breather is used and the oil filler cap must be of the 'vented' type.

To work effectively, the breather system has to create a partial vacuum in the crankcase all the time - the earlier systems did do not do this very well, other than when moving at a reasonable speed, when the breather tube hanging down from the tappet cover acted to draw the fumes from the crankcase.

[alexmcguffie]

But where are your oil leaks from...?

[les]

No leaks to be too worried about but thought I'd make sure the breathers were right, as a first step. I get a weep between backplate and sump.
Thanks Phil for your advice, I'm thinking you are referring to the valve fitted to some minis years back, sticks out the top of the manifold and has a rubber diaphragm held in with a plate and clip?

[aupickup]

http://www.ebay.co.uk/itm/Mini-and-othe ... 2337e147a9

[les]

That's the one Dennis!----be a bit quicker next time!!

[alexmcguffie]

I've never seen on fitted to a Minor. Must have been fitted after 1970?

[IslipMinor]

This is the extract from the BMC Morris Minor Service Manual for the 1098 closed circuit breathing system, using the PCV connected to the inlet manifold - don't know what year it was introduced, but my Parts Manual dated 1966 shows it was used on 1098 engines from 10ME/U/H 101 and later. Does anyone know what year that equates to?
[frame][/frame]

[alexmcguffie]

Could it be an export option? My '67 and '69 don't have it. 99% sure it wouldn't have been removed by a previous owner.

[alexmcguffie]

http://www.classiccarsltd.com/modules/a ... .php?id=11

Found one on an American Minor. I suspect that at around that time it would have been fitted to meet emission regulations there.

[IslipMinor]

Neither the Manual nor the Parts List suggest that it is for export only, just that it is listed for all the 10ME and 10MV engines.

What engine numbers do your cars have, and are they the original units? The PCV did get a reputation for failing after a number of years, and although they are available now from places like ESM, were they as available some years ago and a number were replaced?

[les]

Sorry Richard, not Phil ! The valve in question was fitted to a cooper s 1275 I had, dated '64, can't recall if this has that valve, however the car had the engine stolen, I replaced it with a later unit which I remember did have this valve, so I would say it dates from '65- '66 ?

[Declan_Burns]

This is what Wiki has to say about it:
In 1952, Professor A. J. Haagen-Smit, of the California Institute of Technology at Pasadena, postulated that unburned hydrocarbons were a primary constituent of smog, and that gasoline powered automobiles were a major source of those hydrocarbons. After some investigation by the GM Research Laboratory (led by Dr. Lloyd L. Withrow), it was discovered in 1958 that the road draft tube was a major source—about half—of the hydrocarbons coming from the automobile. GM's Cadillac Division, which had built many tanks during WWII, recognized that installation of PCV on vehicles could bring the first major reduction in automotive hydrocarbon emissions. After confirming the PCV valve's effectiveness at hydrocarbon reduction, GM offered the PCV solution to the entire U.S. automobile industry, royalty free, through its trade association, the Automobile Manufacturers Association (AMA).[citation needed] The PCV system thus became the first real vehicle emissions control device.

Positive crankcase ventilation was first installed on a widespread basis by law on all new 1961-model cars first sold in California. The following year, New York required it. By 1964, most new cars sold in the U.S. were so equipped by voluntary industry action so as not to have to make multiple state-specific versions of vehicles. PCV quickly became standard equipment on all vehicles worldwide because of its benefits not only in emissions reduction but also in engine internal cleanliness and oil lifespan.[2][5]

In 1967, several years after its introduction into production, the PCV system became the subject of a U.S. federal grand jury investigation, when it was alleged by some industry critics that the AMA was conspiring to keep several such smog reduction devices on the shelf to delay additional smog control. After eighteen months of investigation by U.S. Attorney Samuel Flatow, the grand jury returned a "no-bill" decision, clearing the AMA, but resulting in a "Consent Decree" that all U.S. automobile companies agreed not to work jointly on smog control activities for a period of ten years.[
Regards
Declan

[les]

Just checked it was introduced on the 998cc mini cooper in June 1964, when it was adopted for a Minor I don't know.

[bmcecosse]

Les - my 1098 (with 940 head) has no oil leaks - and it's not in the 'first flush of youth'. It does consume some oil - but not wildly excessive. I simply have the rocker cover breather connected to the side pipe of the HIF38 carb (but it used to be a HS2 and worked just as well) - and the tappet cover breather pipe is extended down slightly with a rubber tube - so it exits in the slipstream under the car. There are no fumes and no leaks - and no mayo. I reckon that air is drawn up through the tappet breather and through the block, ventilating it and clearing any water on it's way into the carb, mixed with oil fumes and burned in the engine. The open breather means that in extremis - ie when engine working really hard - any excess block pressure can escape there - without causing leaks. It's simple - and it works well for me.

[les]

Thanks Roy, plenty to consider here, My main concern is to avoid oil leakage.

[alexmcguffie]

The downside to having the tappet breather open to atmosphere is that the engine will breathe in through it as well as out. When it does breathe in it will take in dirt in the atmosphere which isn't ideal for the life of any engine. Any breather open to atmosphere should ideally have a filter. I realise they didn't originally!

My '67 has the tappet breather and rocker cover to air filter breather.

My '69 had only timing cover to air filter breather. It now has a breather filter on the timing cover and another on the rocker cover.

Both with known histories from a relatively low mileage.

If you want to avoid oil leaks, check the source of the crank case pressure which will be worn piston rings.