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What's the small "oil" Reservoir on the 4.3 engine?

bulajim Member Posts: 4

I'm a new owner of a 2000 Fundeck 4.3 IO 201 -- this should be a simple question -- I've had it out 5-6 times and last time when I put it in the water from a lift.  The alarm was sounding constantly -- all gauges looked fine.  Mechanic at Marina correctly thought it was the oil reservoir on the engine (little plastic tank) that was low.  It was and after he added some oil -- alarm went away.  I've put another 4-5 hours on it without issue but have it scheduled to be looked at for possible problems (why did that tank get low).

I assumed that tank (probably 8-12 ounces is all) was an overflow for the lower unit but others i've talked to thought it was trim hydraulic oil.  What is it?

One other detail -- it probably fell in level maybe an ounce after using it for 2 hours.  when the boat was on "trailer" trim sitting in the water, I saw a slight sheen (I was seeing if it would leak on different trim levels).  But I didn't see any sheen without putting it on Trailer.  Would this be consistent with any leak any has seen.  I'll keep it off trailer (sits on a lift 24X7) until we get it figured out.


  • cjjjdeck
    cjjjdeck Member, Moderator Posts: 1,872 ✭✭✭✭
    On my Mercrusier, the tank you describe is for the lower drive unit oil and when it gets low it will sound an alarm.  If you have to add to it regularly, you probably have a leak somewhere and it should be checked out.
    2012 SD237 I/O Mercruiser 5.0L MPI ECT/ Bravo 3
    2012 Load Rite Elite Tandem axle trailer

  • bulajim
    bulajim Member Posts: 4
    Thanks cjjjdeck!  That's what I originally thought-- have it scheduled....