Fuel/oil film

I have noticed when i return to the marina and berth I see a film of fuel/oil residue floating at the rear of my boat. My thoughts are that it is unburn fuel comming through the exhaust.

It only happens when i have been out for a while and not when the engine is running in the marina to warm up. I would see the same thing when i berth at Luss. Its only visible for a few minutes and I would say its fuel rather than oil.

The engine (5.7merc) starts first time and runs like a dream, no missfires or over-run, temp exellent , oil pressure exellent. Although 11 years old it has not had a lot of hours so its in good shape otherwise.

Anyone else get this ?

I think everyone gets this.... and I would say that you're spot on with your "unburnt" fuel diagnosis. No matter how new, good etc your engine is there will always be a very small un burnt fuel trace in the exhaust emissions. I wouldn't worry about it...I don't.

Hi Paul,
Loved the guitar pic!! I see this on boats I repair "Unburned fuel" correct. Depending on health of engine, carb engines worse than EFI engines. EFI's meter fuel much more precisely assuming theres not a problem with system. If engine is EFI I assume you have no other running troubles. Assuming you have no oil loss from drive lube oil header tank, as you would have mentioned this I guess. Depending on point of leakage oil film can also show in that situation.
Nick

Thanks Nick

I kina suspected thats what it was. No other fluid issues at all and the boat is fairly economical so I dont think there is a fault.

I have been asked a few times by other owners who have seen the film at my boat but they are on the opposite side of the leg and their discharge goes the other way ( towards the bow) so its less obvious.

It helps to air some of these things to put boaters minds at ease ( as well as my wife who thinks the boat will burst into flames) so thanks for your input.

Paul