Emulsified Oil

[Simon B]

Not sure how serious this is or exactly what it points (though I do have an idea)

The engine oil in our Yam F100A 4 stroke (carb) has emulsified it's been changed and after a run up shows signs of the same again.

Has anyone else had this problem?

[codprawn]

Deson't sound too clever - obviously water in the oil. On most engines it would indicate head gasket failiure but maybe different on an outboard?

It could be serious condensation problems - maybe caused by the engine running too cold? If you take a sample of the oil and let it sperate out check if the water is salt or fresh - you can either taste it or measure it's boiling point or even evaporate it and see if there are salt crystal left.

[jyasaki]

Milky oil...

Could be water, as Cod says. If it's water, I'd suspect a head gasket.

Could also be fuel getting mixed in. Take a sniff and see if it smells like gas. If it does you've got the condition known familiarly as "making oil". Don't know about the F100, but the F115 is very prone to this (fishermen who troll a lot report this pretty often.) The short version is that unburned fuel gets to the crankcase, condenses, and mixes with the oil. Short term solution is a hotter spark plug and less running at low rpms.

jky

[Simon B]

Cheers JKY,

We're going to run some flushing oil through, it's had one change already, it's happened quite quickly since the last change and during the last trip out it miss fired a number of times but appeared to clear. I put it down to some crappy fuel as it appeared to disappear when we changed tanks. I'll wait a bit before I get morosely depressed. The reports were of strings or spirals of the emulsified stuff forming soon after the new change.

[Sixy_the_red]

Check your plugs too - if the head gasket's gone big style, or the head / block are cracked and cooling water's getting into the barrels the plugs will appear 'jet-washed'.

[Paul F]

Originally Posted by Sixy_the_red

Check your plugs too - if the head gasket's gone big style, or the head / block are cracked and cooling water's getting into the barrels the plugs will appear 'jet-washed'.

Could also be adaptor plate gasket/ water pipe seal at the base of the powerhead.
Paul

[Simon B]

Got a sample of the oil, its a couple of days old now, however, all the "emulsification" has gone its a charcoal grey colour and reeks of fuel. It certainly doesnt look like the emulsified stuff I've taken from gearboxes at work. The chaps who drained it said that the dipstick level was very high.

[Sixy_the_red]

Originally Posted by Simon B

Got a sample of the oil, its a couple of days old now, however, all the "emulsification" has gone its a charcoal grey colour and reeks of fuel. It certainly doesnt look like the emulsified stuff I've taken from gearboxes at work. The chaps who drained it said that the dipstick level was very high.

Sounds like float needles - if they're not seating properly then the fuel pump(?) will simply push fuel past them. The bowls should have overflows but I'd guess if you're leaving the engine tilted then its likely that the fuel will drain into the engine. Fuel shouldn't cause the oil to emulsify though, unless its got dry fuel or preservative in it maybe?

(I once drained 4.5l of 'fluid' out of a 2.5l sump on a bike so you're not alone! )

[jyasaki]

Originally Posted by Sixy_the_red

(I once drained 4.5l of 'fluid' out of a 2.5l sump on a bike so you're not alone! )

Was that the old "Fill it up 'til it overflows out the dipstick tube" trick?

jky

[Sixy_the_red]

Originally Posted by jyasaki

Was that the old "Fill it up 'til it overflows out the dipstick tube" trick?

jky

Naa, more like the 'leave it stood for too long with leaking float needles so it fills the engine up with petrol, sorry gas ' trick!