3.0L GS w/SX Outdrive: seeing fuel sheen in raw water output during summerization

[lamintdog]

Hey all-
I've got a 1996 Volvo Penta 3.0L GS w/ Cobra SX outdrive (~500hrs total) that has a raw water cooling system. At the end of last season I had the shop replace a cracked/warped head due to impeller shred and overheat. They tested everything out after the repair and said it was good to go, then winterized the boat for me. I stored it in an outdoor shed until this weekend. Oil level was fine and looked good, started up fine (fired right up actually) and idled fine w/ muffs on... but...

I noticed that in the exhaust water that was pooling in the driveway, there was a rainbow colored fuel sheen on the top. At first I thought it was just driveway runoff or leftover sludge/fuel/etc in the system from whatever, so I let it idle w/ muffs for about 5 or so minutes, but the fuel slick was still there. I throttled it down to about 3k rpm's and then the fuel slick got much worse...backed off the throttle and it subsided but was still there.
I'm not sure if this is gasoline or perhaps outdrive gear oil? Anyone have any insight on this issue or know what could be causing it? There's probably a bunch of things that could cause it, but I'm not even sure what simple things to check first. Any help is appreciated!

Thanks!

 

[bruceb58]

Re: 3.0L GS w/SX Outdrive: seeing fuel sheen in raw water output during summerization

I see the same thing occasioanlly at startup. Just unburnt fuel due to running a little rich due to the choke. Let it warm all the way up with the choke off and see what it looks like. Probably will be fine.

 

[lamintdog]

Re: 3.0L GS w/SX Outdrive: seeing fuel sheen in raw water output during summerization

Thanks for the reply. I feel like the problem I'm having is more than the motor running a little rich at times... It was enough fuel when I was throttling down to make me worried... especially if I'm getting ready to drop it in the lake. I'd rather be safe than pollute of course...

I'll take you up on your suggestion to idle it until it's warm and see if the output changes... but in the meantime - does anyone have any other suggestions as to what might cause a fuel slick in the raw water exhaust?

Thanks again

 

[Schmoe]

Re: 3.0L GS w/SX Outdrive: seeing fuel sheen in raw water output during summerization

Had the same problem with my 3.0LX. Did some research and discovered that it could be the electronic choke, especially on those infamous Merc-carbs. Adjusted the choke to a leaner setting and that took care of the problem.

 

[lamintdog]

Re: 3.0L GS w/SX Outdrive: seeing fuel sheen in raw water output during summerization

Quick follow up on this: Just to be safe, I brought the boat by my local shop to have them inspect it. They tested it in their tank and found no fuel slick. Engine oil, gear lube were all good. Dropped it in the water this weekend and found no visible slick.

Probably was just auto-choke / fogging oil burn off as you guys had suggested which I'm really glad turned out to be the case. One hour of labor for a season's worth of 'peace of mind'. Worth it in every way as far as I'm concerned.

Thanks again everyone!