Petroleum drops causing small spots of "sheen" on water behind boat.

[scooper77515]

First off, the boat does not leak any oil. Ever. Never see any on any part of the outdrive or on the driveway.

But when we are floating or hanging out on the back of the boat, periodically, like once every 5 minutes, a little spot of "sheen" will pop up and spread out, dissipating within a few seconds.

I don't think it is oil, since it would stay longer.

I am thinking gasoline? Since it appears to spread quickly and evaporate before it floats away. Maybe gasoline vapor from exhaust?

It seems to appear about 3-4 feet behind the boat and off to the starboard side, mostly.

Any ideas? Is this normal?

 

[HT32BSX115]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Howdy,


It's unlikely that it's gasoline.

It sounds more like either outdrive oil or trim cyl oil...... It doesn't take much to do it.

 

[scooper77515]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Is it common for it to drip while in the water, but not on land?

Or do you think it is coming off the trim rams?

 

[HT32BSX115]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Is it common for it to drip while in the water, but not on land?

Or do you think it is coming off the trim rams?

It is only while running or sitting?

Remember that when you have the drive just sitting in the water, you may still have slight pressure on the drive. There's going to be slight (head) pressure on both the trim cyls and drive just from sitting in the water.....

When the drive is cold it may or may not leak at all.

You really do not have a "path" for gasoline to leak in the water with an I/O

The only place for oil to leak is from what's "in the water" ......... Unless you also have Bennett Tabs or other hydraulic tabs, it's coming from your drive or trim cyls(or trim cyl hoses/fittings/connections)


Have you checked all the levels to see if they're dropping?

If it only happens when you're running it can be PS and/or oil coolers too....
(I don't think you have an oil cooler do you?)


Is it right after shutdown or sitting for long periods of time and does it stop after the 5min you mentioned? or does it just keep happening every 4 or 5 min etc?

 

[scooper77515]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Only while sitting with engine turned off. I have not watched to see if it stops after a certain time, but I know we have seen it after 45 mins of sitting.

Levels all look good.

The reason I thought fuel or fuel fumes (maybe from exhaust?) is that is hits the surface and within 3 seconds spreads to about 6" diameter and just evaporates and disappears. I would expect oil to continue showing the sheen, and not just evaporate immediately after it hit the air.

 

[scooper77515]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

I may bring a cigarette lighter out and hold it over one of the spots and see what happen.

Smooooooke on the waaaater. Fire in the sky!

 

[HT32BSX115]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

I may bring a cigarette lighter out and hold it over one of the spots and see what happen.

Smooooooke on the waaaater. Fire in the sky!

I don't know if I would do that


It's very unlikely that fuel could get from the exhaust system to the outside since there's a "water-lock" between the risers and the outside.

If fuel somehow got over the risers, it would float on the water in the y-pipe (inside the boat)

 

[Joshua Nichols]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

yeah my end up being your boat smoking on the water... Sounds like a outdrive leak or grease

 

[scooper77515]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

So, any suggestions to help me figure out what it is and how to stop it?

 

[HT32BSX115]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Well, if it's the drive or you suspect the drive, it should probably be pressure/vacuum checked to see if it will hold pressure. If it won't, then it is leaking......(a little)

If you haven't changed the drive oil recently (in the last few years)

Changing it prior to winter lay-up would be a good idea. If it is in fact leaking, you may find evidence of that....

 

[Gary H NC]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

I had a Cobra drive that did the same thing.
It never showed up as a drop in gear oil but it leaked just enough to see the rainbow pop up on the water while anchored.Just every so often too..
A pressure test found it.A seal behind the impeller was barely leaking.

If you change the gear lube be sure to use new washers for the drain and fill plugs..

 

[scooper77515]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

OK, that gives me a place to start looking.

The oil was just recently changed at the beginning of the season. My season lasts another couple months, so I will look out for leaking seals, etc. when I do the next oil change.

 

[EddiePetty]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

...had the EXACT same symptoms about two years ago !!!! It like to have driven me nuts.
Turned out to be a very slightly leaking flex hose to the trim cylinders. I must have checked them three thousand times while the boat was on the trailer.
Finally, one day I camped out on the swim platform and watched for the area that the sheen originated. Once again checked everything back on the trailer. The XO suggested I wrap a piece of paper towel around each hose and quit for the night....next morning, a damp, oily spot at one of the fittings!!!!

 

[Joshua Nichols]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

I had a Cobra drive that did the same thing.
It never showed up as a drop in gear oil but it leaked just enough to see the rainbow pop up on the water while anchored.Just every so often too..
A pressure test found it.A seal behind the impeller was barely leaking.

If you change the gear lube be sure to use new washers for the drain and fill plugs..

Have that same leak.. Hmmmm must be common.. Oh well thats a easy fix

 

[Gary H NC]

Re: Petroleum drops causing small spots of "sheen" on water behind boat.

Have that same leak.. Hmmmm must be common.. Oh well thats a easy fix

On mine the adapter plate was a real pain to get out.It is aluminum and the factory manual says to pull it with vice grips....lol!
It was more like destroy it and buy a new plate.At least the seals come already installed in the new adapter...

At least scooper has a volvo so no worries there.