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Fuel in oil - where to start?

5K views 42 replies 15 participants last post by  Capt Len 
#1 ·
Hi all-

New to me boat. Gotta love 'em.

Boat has an old Volvo MB10A gas engine. I think four of them were installed in boats:rolleyes:. After a recent test run on the hard (with cooling water) I discovered fuel in the oil. It's hard to start when cold (lots of cranking), but once it starts it runs/idles/accelerates well. Starts right up when warm.

Besides a bad ring, which I'm going to check for soon, what else could lead to fuel in the oil?

I've heard that carb problems can do this. PO(S) stated that "the carb needed to be rebuilt"...could it be as easy as that? At $300 for a rebuild and $750 for a new one, I'd like to know if there is anything else I should eliminate before I go down that route.

Fuel pump is also non-standard...the standard mechanical was replaced with a NAPA electric with a dial regulator. Possible problem here?

Any other suggestions on what to check? I'm game for a thorough list.

THANKS!

--Skagit out :cool:
 
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#42 ·
Hard to say. Looks production, but the boat is 40 years old, so who knows what's been done to it. It's not a good setup regardless...it just defies too much of the proper exhaust theory I've read about. There's just no room before it goes uphill, and it's ALL uphill from that little 6" bend. I'm going to do a dry riser so I can get at least 12" of vertical and inject the water on the downhill side, appx. 18" before the water lift. Also going to add a new water lift, since the one in there is probably original.

Is there an anti siphone valve set up above the exhaust loop? If so is it working?
No. No anti-siphon anywhere. That's another thing on the list. Even if that's not the problem, it's a good way to...you know...not sink, which is always the #1 goal of a sailing trip. That would go between the seacock and the water pump, right?

Hey there Skagit. Where are you working on your project? Located at home on the hard . . . or Somers or Dayton? It would be fun to pop by and take a look sometime.

Regards,

markb
Hey Mark! Welcome back to cold country! I'll PM you and we can set up a time to get together. I'd like to know how your trip went.
 
#43 ·
For fear of water coming back into the manifold at rest , I installed a solenoid type valve on the bottom of the aqua lift. Gets its power thru oil pressure switch from key and closes. Dumps to bilge when no pressure. Anti siphon is necessary regardless and an RV type black water valve at the transom for those big following seas under sail.
 
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