Salad cream!

Hi.

It might be the length of you breather that's the problem. As any moisture vapourfrom the motor travels up the (cooler) breather pipe it condensates out and runs back down the breather tube. A shorter tube to a catch tank might solve this. Try and angle the tube so that any condensate runs out rather than back to the motor.

Regards,

Ian.

The salad cream is a result of water contamination of the oil due to piston ring leakage. Water is a by product of the combustion process. This happens on all engines some worse than others.

On an engine with as good as you can get bores and rings then it should be negligible.

Well i believe thats whats they call it. 1972 750 (combat) runs fine, no smoke and is used on a regular basis for 100mile runs but i still get a creamy white oil discharge from the breather. so much so that i have had to extend the breather up and over to behind the number plate. i keep the oil level on the min on the dip stick and change it often (20/50 classic oil) I dont think its too much to worry about but it sure makes a mess of the block paving. Any advise would be greatly appreciated.

Thanks Mark.

Yes I agree with IAN on this one there not much to worry about. even I get this some times on long runs with my Norton Manxman . the Engine has to breath , so its breathing the heaviest on long runs when the engine is working hard, the warm oil vapor hit cold air and condenses in the breather pipe. just make your self a nice Catch tank. yours Anna J

The water isn't part of the oil, it's water vapour from cylinder leakage, which, as Anna says, condenses in the breather tube and mixes with oil mist to form the salad cream or mayonaisse. Otherwise you'd experience extremely high oil consumption as it evaporated via the breather. It's also not a very good lubricant.

Im with Simon on this. Its blow down past the compression rings- even though the oil rings are stoping oil getting into the combustion space which is why it does not smoke or use oil. My Commando made salad cream until I had it rebored by Hemmings, but now I have to buy it from Tesco, which tastes better than the Norton made stuff

If you have your engine breather routing into the oil tank and then the tank breathing to atmosphere, as your oil tank cools after shutdown, moisture will be drawn into the oil tank as the air above the oil cools and contracts. If you can fit a PVC into the engine breather, close to the engine and allow that to feed a collector tank then you may be able to minimise the mayo. (That catch tank needs to breath as well) The oil tank still needs to breath, ideally into a catch tank close to and below the outlet pipe so any condensation that forms in the pipe does not run back down into the tank.

I have a Yamaha xs650 breather valve close to the back of the timing cover, this feeds into a small plastic drinks container lodged between the engine plates, it has a small drinking spout to breath out of. The oil tank breathes into a HP sauce bottle on the battery tray and collects almost nothing. The original breather feed into the tank is blocked.

Emulsification is the word we should be using. My old Ford Fiesta started emulsifying badly towards the end of its life when it was about knackered. The breather pipes would completely clog up right up to the air cleaner.

I used to have to clean the pipes every week to keep the car running. Some say it's down to short runs but I know it was more to do with wear in the bores and in this case there was plenty.

Previously mark_chapman2 wrote:

Previously mark_chapman2 wrote:

Well i believe thats whats they call it. 1972 750 (combat) runs fine, no smoke and is used on a regular basis for 100mile runs but i still get a creamy white oil discharge from the breather. so much so that i have had to extend the breather up and over to behind the number plate. i keep the oil level on the min on the dip stick and change it often (20/50 classic oil) I dont think its too much to worry about but it sure makes a mess of the block paving. Any advise would be greatly appreciated.

Thanks Mark.

Thanks for the info. i am nowsure that itsdue to combustion passinga piston/pistons although now i know i wont loose any sleep over it as the bike runs fine at present.

Mark.

Could it bemoisture in the air that getssucked into the crankcasethrough the breather when pistons move upwards, then mixing will oil vapour in crankcase, then being expelled when pistons move downwards, then cooling down nearbreather hose end and become an emulsion? Don't know about cumbustion products in this case, Mark says no smoke, so, even more ifcompression is ok, wouldthink rings are ok.

No Bennie, it's piston ring to bore leakage.

wear on the bore start where the top ring stops travelling up the bore an at first the lower oil ring will still work as it is on a good or ta least good enough part of the bore. My own engine breaths but does not leak or burn oil an if it was not for a failed cam it would not be apart waitting a rebore as otherwise ran fine.

It has an XS650 read type valve between the engine an oil tank then the tank breather runs to behind rear number plate an air filter pipe for breather is blocked. But just a little salad cream of the none eating kind can be seen in the pipe from valve to tank but nowhere else.

The only way to stop it is to fix the leaking compression gasses by new rings if you are lucky or a rebore an pistons etc. Even then there may be small amounts in cold weather or after short run but it should not be a constant thing or build up so as to cause a problem a good run should remove it.

Funnily enough back in the days when Commandos were new (and dragons roamed the earth) there was a reasonably well known problem of a build up of emulsion in the oil tank using Duckham's Q multigrade, even in summer with reasonable length runs. A rather better off friend who had a new 750 Commando was plagued by this and a change to Castrol seemed to fix it. Using Q in my even then elderly Dominator I never had the same problem. It tended to froth, but that's a different problem.No, I can't explain it.

Before my commando had its rebore 20,000 miles ago I had lots of elmusification around the oil tank cap, and the oil was streaky with it..

i had the rebore done because it was burning oil like a 2 stroke as well. Since then no emulsification, and the oil looks good. My breathing system is completely standard.

The amount of moisture/water in air is absolutely tiny-nowhere near enoug to condense in an engine breathing system. Not even a sparrows piss amout.

Whereas a gallon of petrol will produce about a gallon water because the oxygen in air combines with the hydrogen in petrol to form water (H2O) in your exhaust gas along with carbon monoxide, carbon dioxide, various nitrojen oxides, and unburnt hydro carbons (CO, CO2, NOX, unburnt petrol.

So if your exhaust gases are blowing past your compression rings that is how water gets combined with your oil to produce emulsification. If the blowdown is say .5% of the cylinder volume each power stroke, over say 20 gllons of petrol that will be a fair amount of water

And because your oil is contaminated with water, petrol and soot its lubrication properties will be poor causing accelerated wear around the rest of the engine, and probably corrosion on any ferrous metals inside the engine due that water combines with other compounds to form acids

So the sooner it has new rings if your lucky, or a rebore, the better for the rest of the engine..

Previously peter_stowe wrote:

Before my commando had its rebore 20,000 miles ago I had lots of elmusification around the oil tank cap, and the oil was streaky with it..

i had the rebore done because it was burning oil like a 2 stroke as well. Since then no emulsification, and the oil looks good. My breathing system is completely standard.

The amount of moisture/water in air is absolutely tiny-nowhere near enoug to condense in an engine breathing system. Not even a sparrows piss amout.

Whereas a gallon of petrol will produce about a gallon water because the oxygen in air combines with the hydrogen in petrol to form water (H2O) in your exhaust gas along with carbon monoxide, carbon dioxide, various nitrojen oxides, and unburnt hydro carbons (CO, CO2, NOX, unburnt petrol.

So if your exhaust gases are blowing past your compression rings that is how water gets combined with your oil to produce emulsification. If the blowdown is say .5% of the cylinder volume each power stroke, over say 20 gllons of petrol that will be a fair amount of water

And because your oil is contaminated with water, petrol and soot its lubrication properties will be poor causing accelerated wear around the rest of the engine, and probably corrosion on any ferrous metals inside the engine due that water combines with other compounds to form acids

So the sooner it has new rings if your lucky, or a rebore, the better for the rest of the engine..

Hi Pete,

Did some rough calcs, please check them, I lost some sleep lately...

Suppose an 850 Commando travels at 110 km/h, at about 4000 rpm, and needs 1 liter of petrol for every 20 kilometers, so about every 11 minutes.So yes, every 11 minutes about a liter of water is produced.Assume a blow-by rate of 1% (rule of thumb for new-build: 0.6%), then 1 liter enters the crankcase every 1100 minutes (18 hours).

Now assume the ambient air was 20 degrC, relative humidity at 60%, this air then contains 10,4 grams of moisture (water) per m3.At 4000 rpm, in the crankcase 828 x 4000 = 3.312.000 cc = 3,3 m3 of air is being displaced every minute.This is moving in and out the crankcase.This equates to 3,3 x 10,4 = 34 grams of water per minute, so about 1 liter roughly every 29 minutes.

So moisture entering the crankcase through venting is almost 40 times the amount caused by blow-by.Mind you, all theory of course, not taking in account losses and efficiencies, quality breathers, etc.Still, I would think (inefficiÃ?nt) crankcase venting would be the biggest contributor to moisture in the crankcase.

Pete, are you sure you 're not using your old bottles-of-whine-winning M20 as a reference here...?Seeya, Bennie

Bennie

It is 01,00 in the morning here now, and I have just got in from the pub where my throat blew down nearly a gallon of Old Hooky at celler temperature. So I am in no state to put together a reasoned response to your last post. I will probably need a day. Or maybe two.

On my Norton Model19, I am currently experimenting with leaning the mixture off to such an extent that at next years Begonia it will tick over for an hour with the fuel taps closed. I will of course share the wine with you.

Best wishes, Pete

And if your breather set-up is acting as a reflux condenser.......................

And if your breather set-up is acting as a reflux condenser.......................