Milky gray oily gunk in exhaust. whats wrong?

Yepblaze

Lieutenant Commander
Joined
Jun 1, 2001
Messages
1,686
Maybe nothing.<br /><br />I've seen a number of times where people try to chase down motor drool only to spend a lot of money and frustration at it and still have it continue.<br /><br />Let the motor sit for a few days and drain the lower unit. Look for water to have separated and come out before the oil.<br /><br />If no water then the lower unit gear oil is probably not an issue. If you drain it right after running it might appear milky yet be only aerated.<br /><br />If the carbs are leaky and what you experience is drool from them. It might be possable to correct, yet many a good fine carbs might dribble when the motor is tilted. Could be considered normal yet washes down the midsection and comes out the bottom.<br /><br />If you have been running in a barrel or on the hose. Or even a lot of idling a two stroke motor can leave a lot of residual behind only to drool out when parked. Especially nowadays during winter when we might choke it a lot more.<br /><br />So if you just ran it hard for a period of time out on the water and haven't tilted the motor and it's all gooey on the floor it sounds like an issue.<br /><br />But if you are running it for any period of time at idle, and perhaps on the hose. Then tilted, and dropped the motor again....... it may be normal to see it puddle goop.<br /><br />Go ahead and check the lower unit oil, but like I said it can take a few days even during the warm days of summer till the water will settle out of the oil to become redily apparent when draining.<br /><br /><br />Hows it run? If it's dropping a cylinder or two it will only increase any unburnt fuel oil left over to drool also.<br /><br />If you do find water in the lower unit, you'll need to remove it and pressure test it to find the area(s) of concern.
 

Ricky2

Cadet
Joined
Nov 10, 2004
Messages
10
Milky gray oily gunk in exhaust. whats wrong?

I have a 1971 mercury 135hp. There is this milky gray oily gunk coming out of the exhaust (upper port & prop exhaust) What's wrong and how do I fix it?
 

Ricky2

Cadet
Joined
Nov 10, 2004
Messages
10
Re: Milky gray oily gunk in exhaust. whats wrong?

It seems to run okay. It's a bear to start now that the weather has cooled. I had the carbs tuned this past May. I've had this motor for about 5 years now, it's never happened before. This has happened the last two times I have taken it out. The second time was even worse. I don't understand how the lower gear case oil would end up in the exhaust? I have expierenced the black oily residue that sometimes drips out of the prop exhaust, I understand this normal. This milky stuff is different.
 

flips

Petty Officer 2nd Class
Joined
Dec 18, 2001
Messages
160
Re: Milky gray oily gunk in exhaust. whats wrong?

If it has milky look it has to be getting water from somewhere, if it is hard to start and not before must be up the top end. only guessing as i am not a mechanic but love motors
 

phatmanmike

Captain
Joined
Oct 24, 2003
Messages
3,869
Re: Milky gray oily gunk in exhaust. whats wrong?

my evinrude did this. it was water mixing with the fuel through a cracked exhaust plate. it will look milky because the fuel ( which is essenyially oil) has oil in it, and we know what happens when oil and water mix, it gets milky and thick.<br /><br />id suspect your exhaust cover plate and /or gaskets. also check your cylinder cover gasket, do that one first as its the easiest to get off. the exhaust gaskets equire removing the powerhead.<br /><br />either that or you have a crack internally in the block somewhere...lets hope thats not it!
 

Yepblaze

Lieutenant Commander
Joined
Jun 1, 2001
Messages
1,686
Re: Milky gray oily gunk in exhaust. whats wrong?

It is possable to have a seal fail where the shift shaft enters the lower unit and gear oil/water to get out and up into the midsection.<br /><br />But the poorer it runs the more unburnt fuel will accumulate there also.<br /><br />Check the gear oil after a few days then if no water present, concentrate on the poor running.<br /><br />Might be the one or more carbs overflowing a bit at idle causing poor idle and excess fuel/oil to drain down through the midsection.<br /><br />After 5 years it might be time to have the carbs removed and gone through. But during the diagnostic procedure you'd want to check (or have checked) the compression, spark plug appearance, and perhaps the spark.
 

Ricky2

Cadet
Joined
Nov 10, 2004
Messages
10
Re: Milky gray oily gunk in exhaust. whats wrong?

Thank you all for your insight. I now have a place to start diagnosing. I'll let you know how I made out. Thanks again.
 
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