grey milky oil during oil change....

[al0311]

recently acquired a 1990 galaxy walk around boat with 4.3 v6 merch.
first issue I had was a fuel starvation problem which fixed once a I rebuilt the carb. now boat starts idles and runs fine. YEAHH.
go to look at the fuel pressure and thought it was kinda low at around 30 at idle with a mechanical gauge plunged in. so I figured maybe the oil filter was dirty or maybe the oil was just dirty since the boat has been sitting for a year.
go the change the oil and it ends up being this grey milky color.
so what am i looking at that would cause the oil to turn this color?
most posts point to water mixing with the oil? how does this happen?
some posts saying a blown head gasket or cracked block??? god i hope its not that.

What I was going to do was change the oil and filter and see if that makes a difference first? then do a compression test?
which leads me to my next question about compression testing. I've never done one before so I really don't know where to start.
Correct me if im wrong but do you ground the ignition coil on the distributor first and then disconnect the fuel lines? how do you ground the ignition coil?
then go ahead and un-plug all the spark plugs and start testing? i consider my self a pretty visual learning type person so if you got some pics that would help.
thank you guys so much.

 

[tpenfield]

I think you mean 'oil pressure' not 'fuel pressure'

30 psi at idle is not terrible

Gray milky color - Gray could mean old, milky usually means water.

Most of the times, water in the oil is from a crack in the engine (somewhere) . . . it can also be as a result of water in the cylinders due to a failing exhaust elbow gasket.

Change the oil as you mentioned and run the engine for a while . . . and then some more. See how the oil looks after the engine has been run.

Compression test is best done on a warm engine. You can Google compression test procedures . . . auto vs boat are pretty much the same. You can ground the coil wire by taking it off the distributor and plugging it into a bolt or stud that is within reach. The key thing is not to be throwing an open spark.

Usually the compression test gauge will get a good reading after 4-5 compression strokes.

This is a carbureted engine ??? Not fuel injected. . . . Not sure what you mean by "disconnect the fuel lines" :noidea:

 

[al0311]

I think you mean 'oil pressure' not 'fuel pressure'

30 psi at idle is not terrible

Gray milky color - Gray could mean old, milky usually means water.

Most of the times, water in the oil is from a crack in the engine (somewhere) . . . it can also be as a result of water in the cylinders due to a failing exhaust elbow gasket.

Change the oil as you mentioned and run the engine for a while . . . and then some more. See how the oil looks after the engine has been run.

Compression test is best done on a warm engine. You can Google compression test procedures . . . auto vs boat are pretty much the same. You can ground the coil wire by taking it off the distributor and plugging it into a bolt or stud that is within reach. The key thing is not to be throwing an open spark.

Usually the compression test gauge will get a good reading after 4-5 compression strokes.

This is a carbureted engine ??? Not fuel injected. . . . Not sure what you mean by "disconnect the fuel lines" :noidea:

thank you so much for the quick reply yeah sorry i meant oil pressure not fuel pressure.

the oil was more of a grey color more than milk. God i hope its just old oil and not something major.

yes its carbureted ahahaha I think I read some where that the fuel supply needs to be cut off before doing the compression test is this true?? or maybe im just tired and losing my mind.

 

[tpenfield]

The engine is going to suck some fuel into it during a compression test. Not a lot you can do about that. Just try not to crank it too much as excess fuel will tend to wash the oil off the cylinder walls and reduce the compression reading.

Throttle should be wide open,

Battery should be well charged and keep on a charger if you can so that the last cylinder that you test has gotten an equally charged battery as the first cylinder you test.

Google some procedures. for more details. Post your results . . . you are looking for consistency as well as the actual value.

 

[al0311]

The engine is going to suck some fuel into it during a compression test. Not a lot you can do about that. Just try not to crank it too much as excess fuel will tend to wash the oil off the cylinder walls and reduce the compression reading.

Throttle should be wide open,

Battery should be well charged and keep on a charger if you can so that the last cylinder that you test has gotten an equally charged battery as the first cylinder you test.

Google some procedures. for more details. Post your results . . . you are looking for consistency as well as the actual value.

thank you so much for your quick reply I just want to make sure I do it right and safely. I'll post the results as soon as a I can.

 

[Scott Danforth]

30 psi at idle is good oil pressure. Ted has you in the right direction with the compression test. if the cylinders come back within 5% of each other and in the 140ish range, the compression is good.

change oil and run it. could be just needing an oil change. however if it comes back milky again, you are going to have to pressure test to find the breach.

 

[wahlejim]

The only thing I would add is that if you are on dry land, hook up some muffs to the outdrive. Don't want to be turning a dry impeller around. With the spark plugs out, you will also be able to observe any water that makes its way to the cylinders.

 

[al0311]

Hey guys so I got up today and went out to work on it only was able to mess with it for a little while before the rain set in. One think I did notice was the oil I pumped out has a gas smell to it. Oh and it's defiantly grey not milk color.

 

[Maclin]

Sounds like you have or had a carb overflow problem with flooding. I am not sure what type of fuel pump is on that one, was thinking it was electric, but if it is a mechanical one then the pump could have ruptured internally and fuel is dumping right into the crankcase. If you fixed the carb then the one oil change should be enough, unless the fuel pump is a mechanical one and is compromised.

 

[al0311]

Sounds like you have or had a carb overflow problem with flooding. I am not sure what type of fuel pump is on that one, was thinking it was electric, but if it is a mechanical one then the pump could have ruptured internally and fuel is dumping right into the crankcase. If you fixed the carb then the one oil change should be enough, unless the fuel pump is a mechanical one and is compromised.

Yeah Iam not sure what kind of fuel pump I have how would I be able to tell?
I was reading on some other posts saying the diaphragm could be broke does that sound reasonable?
Also, I did have an issue with the carb Which is why I had to rebuild it I had a fuel starvation issue and one of the carbs jets were all gunked up.

 

[Maclin]

I believe it is a mechanical fuel pump if the engine has not modified. Looking at front of the engine it is down low on the left. There should be a small clear-to-yellowish small tube running from the pump to the flame arrestor. That is the vent for a leaking internal diaphragm. If there is fuel in that tube the pump needs to be replaced. A leaking fuel pump diaphragm can dump a lot of fuel into the crankcase when running, enough to raise the oil level and dilute the oil and reduce lubrication properties. You need to make sure the fuel pump is not compromised.


If it was just the carb flooding then the amount of fuel getting to the crankcase is not quite as much volume as a pump leak as it has to get past the rings but still can wipe out an engine soon enough if not checked.

 

[al0311]

I believe it is a mechanical fuel pump if the engine has not modified. Looking at front of the engine it is down low on the left. There should be a small clear-to-yellowish small tube running from the pump to the flame arrestor. That is the vent for a leaking internal diaphragm. If there is fuel in that tube the pump needs to be replaced. A leaking fuel pump diaphragm can dump a lot of fuel into the crankcase when running, enough to raise the oil level and dilute the oil and reduce lubrication properties. You need to make sure the fuel pump is not compromised.


If it was just the carb flooding then the amount of fuel getting to the crankcase is not quite as much volume as a pump leak as it has to get past the rings but still can wipe out an engine soon enough if not checked.

its funny you mention that tube on the back of the carb every pic I have looked up of my engine I see that yellow tube that plugs into the back of the carb but on mine it has been removed?
why would someone do that?
Also, dumb question but how would fuel dump into the crank case from the fuel pump?

 

[Scott Danforth]

if the fuel pump fails, the two places it dumps fuel are internally where the lever arm is, directly into the crank case, or thru the yellow vent tube into the carburetor

 

[Maclin]

al0311, Marine pumps are dual diaphragm for safety, the tube is in the cavity between them I think. Your fuel pump may not be the correct Marine version and not even have the fitting for the vent tube. A mechanical pump works from a lever that rides on the camshaft, and the way the pump itself is mounted on the block the "other side" of the diaphragm(s) are exposed to the crankcase.

 

[al0311]

al0311, Marine pumps are dual diaphragm for safety, the tube is in the cavity between them I think. Your fuel pump may not be the correct Marine version and not even have the fitting for the vent tube. A mechanical pump works from a lever that rides on the camshaft, and the way the pump itself is mounted on the block the "other side" of the diaphragm(s) are exposed to the crankcase.

Yeah I was just out looking at it there is no fitting for the vent tube weird right?
I mean when the motor runs it idles and runs fine iam guessing that wouldn't be possible if the fuel pump had a bad diaphram correct?

 

[Scott Danforth]

Yeah I was just out looking at it there is no fitting for the vent tube weird right?
I mean when the motor runs it idles and runs fine iam guessing that wouldn't be possible if the fuel pump had a bad diaphram correct?

it would idle and run just fine with a bad diaphragm.

if there is no fitting for the vent tube, get the proper marine fuel pump.

 

[al0311]

it would idle and run just fine with a bad diaphragm.

if there is no fitting for the vent tube, get the proper marine fuel pump.

Welp finally got outside today and was able to change the oil. After I changed the oil and filter the mechanial oil pressure gauge is reading zero???? Come on.
It did have oil pressure before it was at 30 at idle.
Now it has zero.
No idea what I did wrong. There is oil on the dipstick so I know it has oil.
I was reading on some other posts that say the oil pump can loose its prime???? Or it could be a bad filter? Lol never heard of that.
Where should I proceed now. Get a priming tool and self prime it ? Change the oil filter again ? This is getting frustrateing .

 

[dusted_ya]

If it's an electric oil pressure gauge you could have inadvertently unplugged the sender during an oil change or something. The only way you would have 0 oil pressure is if your oil pump failed (not likely), you threw a lifter out of it's bore (even more not likely), you popped an oil galley plug (possible but still very unlikely) or your oil pickup tube is completely clogged (again very unlikely). If your oil filter was completely clogged it would bypass causing the filter to be useless (again highly unlikely)

Now I am not taking into account that your oil change included reinstalling the drain plug and refilling with fresh oil of course...