Mercruiser 5.7/Alpha One Oil Slick with engine running

1

117

Cadet
Joined
Jul 20, 2011
Messages
6
Hi Guys,

Recently Purchased a late 80's Donzi Ragazza 25 with Mercruiser 5.7/Alpha One outdrive.

Boat was placed on pontoon mooring, and took the boat out for the first time around 3 weeks ago however didnt go above 1/4 throttle at any point as was running at low speed for an hour or so practicing docking technique etc. then weather turned so didnt get chance to open her up (everything fine at that point however).

Went back yesterday and started her up, only to find rainbow slick of what I presume is oil around the outdrive at idle almost immediately, but no traces of oil when engine switched off. Tilt/trim works fine and engine oil level looks ok, and boat engages gear ok, but as I am a novice didn't want to take her out if something is leaking! Does anyone have any experience of a similar situation? Is it possible that it is unburnt fuel and just needs a good run?

Would really appreciate any advice you guys have!
 
Bondo

Bondo

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Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

117 said:
Hi Guys,

Recently Purchased a late 80's Donzi Ragazza 25 with Mercruiser 5.7/Alpha One outdrive.

Boat was placed on pontoon mooring, and took the boat out for the first time around 3 weeks ago however didnt go above 1/4 throttle at any point as was running at low speed for an hour or so practicing docking technique etc. then weather turned so didnt get chance to open her up (everything fine at that point however).

Went back yesterday and started her up, only to find rainbow slick of what I presume is oil around the outdrive at idle almost immediately, but no traces of oil when engine switched off. Tilt/trim works fine and engine oil level looks ok, and boat engages gear ok, but as I am a novice didn't want to take her out if something is leaking! Does anyone have any experience of a similar situation? Is it possible that it is unburnt fuel and just needs a good run?

Would really appreciate any advice you guys have!
Click to expand...

Ayuh,... Welcome Aboard,.... An oil slick is Never a good thing,...

Did ya check the oil level, 'n condition in the Outdrive,..??
 
Don S

Don S

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62,321
Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

Are you sure it's oil and not un-burned fuel?
 
1

117

Cadet
Joined
Jul 20, 2011
Messages
6
Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

Hi Guys,

I can't easily check the level/condition of oil in the outdrive, as the boat is on a pontoon, and would need craning out to check as the leg is underwater, the boat was serviced recently and no evidence of gear oil leak whilst in storage.

It could well be unburned fuel Don, do you know what could cause that? Also could the fact that it only occurs when engine is on support that?

Thanks for your help guys.
 
Don S

Don S

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Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

It could well be unburned fuel Don, do you know what could cause that?
Click to expand...

When cold and you first start it, the choke is on and that WILL run the engine rich. Could be the idle mixture is too rich, carb problem, may not be firing on all cylinders due to needing a tuneup, bad plug wires. One of those things where it would be nice to be there and hear and see it run.
 
series60

series60

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Jan 4, 2010
Messages
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Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

117 said:
Hi Guys,

I can't easily check the level/condition of oil in the outdrive, as the boat is on a pontoon, and would need craning out to check as the leg is underwater, the boat was serviced recently and no evidence of gear oil leak whilst in storage.

It could well be unburned fuel Don, do you know what could cause that? Also could the fact that it only occurs when engine is on support that?

Thanks for your help guys.
Click to expand...

I'd put it on a trailer and check outdrive before taking it out to open it up. If not you run the risk of toasting the outdrive and the engine coupler! Granted this being worst case but it's your money.
 
1

117

Cadet
Joined
Jul 20, 2011
Messages
6
Re: Mercruiser 5.7/Alpha One Oil Slick with engine running

Thanks for your replies guys,

I am getting the service guys at the marina to look at it this week, so I will report back with a diagnosis and hopefully a resolution! I agree that it is not worth risking expensive components until the problem is correctly diagnosed!
 
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