Milky White floating in engine bilge?

[LeeV]

I’ve only had outboards on our trimarans so diesels are a whole new adventure for me - esp since I’m not exactly a gear head!

Yesterday we looked at a boat with twin 4JH4AE engines. On one side there was a fair amount of white stuff floating in the bilge. Can someone tell me what that might be? I tried searching but didn’t find anything specific to that; is this something to be concerned about?

Thanks so much,

[weavis]

Could be water in the bilges with diesel or oil dropped in it..

Check the oil in the engine is just oil and not the same as bilges..

[LeeV]

Originally Posted by weavis

Could be water in the bilges with diesel or oil dropped in it..

Check the oil in the engine is just oil and not the same as bilges..

I meant the the engine compartment bilge, not the boat bilges.
Sorry!

[weavis]

Again. Check engine oil.

[GordMay]

As weavis implies, "milky white" liquid could be a mixture of oil (fuel or lube) and water.

[Bill O]

Was the "white stuff floating" solid or liquid?

As mentioned an oil emulsion could look milky, but not usually found in the engine bilge. Usually this type of emulsion is found in engine oil after running that as a oil:water, while oil typically just floats in the bilge.
If it looks solid then its probably some fouled bilge water that's been sitting in there for a awhile. Did it have an off smell also?
If this is a boat you are looking at to purchase, try to get sample out and look at it in a clear jar. If it more than residual oil (it is an engine bilge so expect a little oil) you should be able to tell. If it is a lot of oil, the engine should have a noticeable leak.
If it just scum, then it needs to be cleaned out otherwise it will really stink when the temps get warmer. Also look to see how water was able to get there to sit in the first place. Check the stuffing box (if direct drive), deck. etc. for leaks. Any noticeable difference (besides water) between the "dry" engine and the engine bilge of concern?

Also typically you would not have a float switch in an engine bilge area as that would be environmentally bad by discharging residue into the outside water. Is this bilge also a shower or sink drain accumulation area (instead of direct over)? If so, it could be scum growth from food products, hair products (conditioner), etc. If this is the case, expect to clean this bilge often to remove food sources for bacteria/scum to grow which eventually leads to bilge stink.


Bill O.

[roverhi]

Appears to be a powder like residue possibly from grinding fiberglass. Definitely not oil as that would just be a slick on top of the bilge water. Oil in the bilge doesn't get milky unless strongly agitated like in the crankcase of an engine. Even then it will precipitate out of the water and return to an mostly oil state floating on top of the water given a little time.

[TrentePieds]

BillO has laid it out clearly. Just for the sake of greater certainty: We differentiate between "the bilge" and the "engine bilge" because they serve two different functions. I like referring to the "engine bilge" as the "drip pan". I my boat the drip pan is separated from the bilge proper by a "containment dam".

It is not possible, in my boat, to change oil without a very small quantity of oil escaping from the old oil filter into the drip pan. Similarly a small quantity of coolant may escape from the header tank due to expansion of the fluid as the engine warms up or during a violent roll. This resultant grunge is prevented from entering the bilge proper (and making a mess) by means of the containment dam. However, it's a bit of a primitive arrangement and I'm careful about always wiping the drip pan clean. A visual inspection of the engine compartment's sundry fittings is part of the start-up and shut-down routine. Any scuzz found is analyzed and removed during these inspections.

So what you see may be normal for the boat you are looking at and just require "normal" boat-keeping. As BillO sez: A drip pan or "engine bilge" should NOT be fitted with an automatic pump! "Stuff" accumulating there should be examined carefully as a diagnostic for your engine's health, and should then be disposed of in an environmentally acceptable manner.

For the sake of convenience, and sometimes as a result of retrofitting, grey water (which generates white scum) from a shower is sometimes taken from the "shower sump" (what amounts to a drip pan for the shower) into the bilge proper whence it's pumped overboard. Silly arrangement IMO. Since it's gonna go overboard anyway, why contaminate your bilge with scum? Pump the stuff directly overboard via a separate pump while the shower is being used.

TrentePieds

[jmschmidt]

Check what the others have said but also could spilled coolant, which is usually green or yellows but who knows. Smelling or even tasting it also may reveal something. Even if it tastes good don't drink it.

[TrentePieds]

PARTICULARLY if it tastes good, don't drink it! That way lies kidney failure.

TP

[jmschmidt]

I've tasted bilge water dozens of times, mainly to see if its fresh or salt. Like a wine or coffee taster, I spit it out between tasting sessions and rinse with fresh water, other wise the high notes and after-taste will linger and spoil the next tasting.

[Mike Banks]

Others may give you a better answer, but I suspect this is synthetic oil which has either leaked from a gearbox or engine or been spilled by someone when topping up.

It needs to be removed by skimming and sponges, and taken for analysis. If it really stinks, it could be bacterial or fungal, but if no organinc smell then almost certainly an oil lubricant.

[skipper53]

If dish detergent disolves it, it may be oil.

[GordMay]

Originally Posted by skipper53

If dish detergent disolves it, it may be oil.

The application of a detergent (or any surfactant or emulsifier) to an oil slick disperses the oil (transfers the floating oil into the water column as small droplets), but it does not remove (or dissolve) the oil from the water.

A solution is a mixture of one substance DISSOLVED in another substance. It has a solute and a solvent.
Sugar in water would be an example of a solution.
A dispersion is a mixture of one substance PHASE SEPARATED from another substance. They phase separate because they DO NOT dissolve with each other.
For example if you take oil and water, and shake it really hard, you would have a dispersion of oil in water.

[a64pilot]

Originally Posted by GordMay

The application of a detergent (or any surfactant or emulsifier) to an oil slick disperses the oil (transfers the floating oil into the water column as small droplets), but it does not remove (or dissolve) the oil from the water.

No, but the emulsified oil is very often white, if you go to a machine shop and watch them machine steel, they will often use a white coolant, which I believe is just water with emulsified oil.
If they have ever gotten oil into that pan which is likely, and used detergent to clean it, then it’s likely they have emulsified the oil.

Making the oil mix with water is why using Dawn dishwashing liquid to “disperse” a fuel spill at the fuel dock is a big no-no now, where it used to be the norm.