Drive Oil - how much should I use?

[Steve_D]

I've noticed that the drive oil goes down each time we go out, down to about the refill line each time. I dutifully check it and top it up and the next time we go out its back down to the refill line again

We're using a Mercruiser 4.3L alpha, circa 1999, 135 hours use, recently fully serviced.

should we be losing/using this much drive oil? is there a problem or is this normal?

as ever your collective wisdom is gratefully received

Regards

Steve D

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[DavidJ]

No experience of this engine but generally, yes you have a problem. For the few hours that boat engines do (ave 100hrs per year?) I would expect never to top up and for the annual service to restore back to level.
You don't mention masses of smoke, ...I wonder where the oil is going?
David

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[Russell]

Was the drive oil changed when it was serviced ? If so and it wasnt refilled correctly (ie from the bottom) then there may have been air trapped in the leg and this is slowly being replaced by the new oil. Dodgy situation cos the leg may not have enough oil in it......


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[DepSol]

Sorry steve didnt mean to snob you on th way in the other day I was just concentrating on mooring.

<hr width=100% size=1>Dom

2003 is going to be a good year for me

 

[tr7v8]

Doesn't the Mercruiser use an inboard filler and reservoir?
If it was a Volvo you'd have never known until you lifted it out of the water, but I suspect you have a leak in the leg. How much are you topping up each time?
Probably bottom seal at a guess, where is Spannerman when you need him, he's the merc expert.

<hr width=100% size=1>Jim

Draco 2500

 

[Steve_D]

Sorry - went on holiday

and couldn't get a decent isp feed in bonny scotland.

to answer all of the points below

we're topping up about 1cm on the filler thingy from the "top up line" to the "full line"

Not a lot of smoke is evident.

The engine was recently serviced apparently they fill the leg separately and expect some topping up I guess I'll just have to keep an eye on it.

Dom. No problem we had a bad hair day - finished putting in the new gadgets ready to set off into the sunshine - flat battery!!!! it wouldn't take a charge either so it had to be replaced.

Thanks for the input

Steve D

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[duncan]

Re: Sorry - went on holiday

Steve - I had this with my BIII from new; and we never did find out the reason the oil was going down (being used). I reckon I got through the difference between the levels in about 50 hours.
On having the drive removed and put back (long story) the 'problem' has go away and I have added about 10mm of top up in the last 200 hours....beats me!

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[AJW]

Dont want to worry you but

Experienced drive oil consumption on Yanmar 300, Bravo 3x drive in 9.5m Cabin RIB owned by mate of mine. We circumnavigated UK in 2001 and had to top up significantly every day. After the circumnavigation inspection of leg at service time found problems and led to replacement under warranty. (It was a virtually brand new boat). Same boat last year and trip from west country upto and around the Outer Hebrides. Oil needed topping up daily and then 20nm out from Stornoway enroute to Kyle, crunch, grind, bang, complete drive failure! Fortunately we were cruising in company & lots of help to hand + weather was fine. New B3x leg shipped to Kyle & replaced for trip to continue. However that was 2 x B3x legs in 250 hrs or so. Loss of confidence in drive / engine combo (for solo cruising at least!) led to replacement with B1 drive & much happier owner.

Now this may have been a problem with this particular engine drive combo or this particular engine/drove combo in Ribs but it might be worth seriously investigating any continual oil usage. Its gotta be going somewhere?! BTW the drive that failed in Scotland was cooked - paint blistered from the outside. And it was fitted with aftermarket "shower head"!

AJ

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[jon_bailey]

My 4.3L with Alpha drive did not need topping up at all last season. Similar age and use as yours.

Highly unlikely to see smoke because leg has separate oil system to engine. Do you notice oil around prop or anywhere else on leg?

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[Steve_D]

I thought that the oil system was separate for the drive leg. I've not noticed any oil leaking out but I'll take more notice next time I'm down at the boat.

Thanks

Steve D

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[ArthurWood]

Steve-ask at Boatdoctor.com. They are Merc experts.
I have Merc Alpha on a 1987 boat, but drive leg filling is done from the bottom of the leg to expel air and it's full when oil comes out a hole at the top. This normally only needs to be checked every 100hr as others have said. Sounds like later models are different if you have a filler at the top. Anyway, seems you have a problem and need to get it checked out before you hear grinding noises.


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[Steve_D]

Thanks, I think we will.

REgards

Steve D

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