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Author Topic:   Lubricating Oil Present in Cooling Water
howlingdogsteve posted 04-12-2008 07:55 AM ET (US)   Profile for howlingdogsteve   Send Email to howlingdogsteve  
[Perhaps not directly related to Boston Whaler boats first designed after c.1990]

I'm new to outboards, had a Merc [sterndrive] for 20 years. Just put the boat in the water after winter layup and finding that [the Mercury 90-HP FOURSTROKE outboard motor] is smoking a little. Also, seems to be a putting out a slight bit of oil. I see tiny oil droplets from the [aspirator] stream. Seems the same after 20 minutes of idling. Should I be concerned about this? Thanks, Steve

dbrown posted 04-12-2008 10:08 AM ET (US)     Profile for dbrown    
Steve, I'm going to guess that you will be asked which model [outboard motor] you have. Is it the older carbed model or the newer fuel injected one?
boatdryver posted 04-12-2008 01:02 PM ET (US)     Profile for boatdryver  Send Email to boatdryver     
what color is the smoke, blue, black or white?


jimh posted 04-12-2008 05:23 PM ET (US)     Profile for jimh  Send Email to jimh     
Oil in the cooling water exhaust is a sign of a serious problem. There should be no mixing of the lubricating oil system and the cooling water system. If your Mercury FOURSTROKE outboard motor under warranty, I recommend you immediately have it checked by your dealer
howlingdogsteve posted 04-12-2008 08:33 PM ET (US)     Profile for howlingdogsteve  Send Email to howlingdogsteve     
It's a 2006 EFI 90 HP Mercury.
The smoke appears to be whitish grey.
There is very little smoke but I don't remember seeing any last year.
I got the boat late in the season.
Oil is minimal as well but I do see it.

bigjohn1 posted 04-13-2008 08:31 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Too many variables and possibilities here for an accurate "internet diagnosis". Your location is not in your profile but perhaps it was warm last season when you last used the boat and now its cold hence the possible cause of some smoking. Perhaps when it was winterized, an excessive amount of fogging spray was used and it is now burning out and causing some of those oil droplets. Perhaps someone overfilled the engine oil during the last oil change. The exhaust port and cooling system pee stream outlets are right next to one another.

It is remotely possible you have a blown head gasket or cracked casting which is allowing oil into the cooling water but, assuming nobody did anything blantantly wrong like running the engine with no water for an extended period of time, that is not a likely scenario on this engine.

You have both an audible low oil pressure warning buzzer and an audible low water pressure warning buzzer. Its your engine so you must do what you feel is prudent. That said, if it were me, I wouldn't immediately fear the worst and run down to your dealer just yet. I'd take it out for a few miles and get the engine heated up to normal operating temperatures then see if it is still doing it. My bet is that all will be fine after the engine gest hot but if it isn't, then you can take it to the dealer and have it fixed for free under warranty.

howlingdogsteve posted 04-13-2008 12:17 PM ET (US)     Profile for howlingdogsteve  Send Email to howlingdogsteve     
I live on Long Island and yes the last time I ran the boat the weather was fairly warm. I fogged it and that seemed to burn of in the first 30 seconds of running the motor on land. I changed the oil prior to starting it up and it drained nearly 5 quarts. I filled it with 4 3/4 quarts.
I did make the switch from regular 10/30 merc to syn blend 25/40 merc.
Other ideas?
dbrown posted 04-13-2008 02:07 PM ET (US)     Profile for dbrown    
I would say that what you are seeing is normal for the first run of the year. Some oil being spit out is probably from the fogging oil and the smoke could be caused by the cold air temps. Pull the dipstick and have a look to see if any water droplets are present and keep an eye on the oil level.
sosmerc posted 04-13-2008 09:11 PM ET (US)     Profile for sosmerc  Send Email to sosmerc     
Collect a sample of pee-stream water into a clean glass container. Let it sit for a bit to see if any "layering" occurs. (oil on top of the water) I really don't think there should be ANY signs of oil in this water.

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