96 Merc 25 excessive oil in cowl

[woodsrun]

I have a 96 Merc 25 Tiller that spends most of its running time at trolling speeds. After a trip to the local tech school for a tune up and new impeller I notice an excessive amount of oil in the cowl and actually draining down and coating the whole lower unit after a couple evenings of trolling. Also after about an hour of trolling the motor backfires with an extremely loud whistle I'm assuming from the carb. Any thoughts on this ?

 

[Anchor Marine Repair LLC]

Re: 96 Merc 25 excessive oil in cowl

I have a 96 Merc 25 Tiller that spends most of its running time at trolling speeds. After a trip to the local tech school for a tune up and new impeller I notice an excessive amount of oil in the cowl and actually draining down and coating the whole lower unit after a couple evenings of trolling. Also after about an hour of trolling the motor backfires with an extremely loud whistle I'm assuming from the carb. Any thoughts on this ?

Without looking at it, I'd say one of your recirculation hoses is leaking. There's hoses that just take excess fuel/oil mix from certain areas of the motor and let's it flow to another. The back fire means its running lean or sucking air. And you can backfire or "whistle" through an open recirc hose. I had one that sounded like a pellet gun snapping off a round. I'd trace your recirc hoses (little tiny guys) and make sure they're connected and in 1 piece.

 

[woodsrun]

Re: 96 Merc 25 excessive oil in cowl

Thank you for the tip . It is back at the tech school and I told them what you said.