Loose Anode Saildrive 120SE

[1simon]

Hi All,

Last weekend I noted black smoke form the exhaust of my Bav Ocean 38 1999 after a sudden increase in throttle to 3000rpm.
Spoke to  mechanic and he advised that probably prop was fouled with fishing line or rope or needed cleaning.

I  went out of the marina (  not visibility there) and exhaust did not emit black  smoke.
I then went under and checked the prop. I found no fishing lines or rope and no growth. What I di note was that the anode had come loose completely from  the bottom screw and was loose also  from the top one.

Advised the mechanic who told me that this could  unbalance (?) the shaft making it harder to rotate especially at higher rpm thus leading to overloading of the engine.

2 questions:-

[1simon]

HI All,

Apologies for the abrupt ending of the post!

2 questions:-

[1simon]

Apologies once more! Continuing my post below:-

2 questions - (1) has anybody encountered this kind of problem before?  (2) can the anode be re screwed in place without haulout and without taking the prop off?

Thanks for any feedback

Simon

[Impavidus]

Simon Hi.  I rather doubt that the smoke issue is the lose anode as they wear or get chewed up when they come loose. It is not uncommon. They normally do this when the fixing are not done up evenly (one turn at a time) the anode binds on the screws and gives a false torque and the anode is not fully bedded on to the drive leg casting.

You will find a link below to your saildrive workshop manual and as you can see the prop has to come off to tighten the screws. I good diver should take 15 mins to do the job under water, which is probably cheaper?  Its only the split anode types that can be replaced without removing the prop.

http://www.bavariayacht.info/downloads/volvo-penta-saildrive-120s-workshop-manual.pdf


Does the engine emit black smoke when revved up out of gear? Lack of power/speed when underway?   If so the most likely cause is a blocked or partially blocked exhaust elbow as the black smoke is un-burnt fuel caused by too much back pressure. Its very unlikely its the anode rope or net overloading the engine to cause this it would need to be an arm full of it  and that amount of rope or net would be very obvious to you vibration wise.  They are easy to diagnose and change yourself. Does you boat have the MD2030 engine?

Anode and blocked exhaust as below.

Best regards

Ant.

 

[Odysseus]

2 things I have done for your isseus.

The anode screws I changed to hexhead bolts and use threadlock when you put them in. Buy a bag of them from Toolstation .£2  ish  change them each year.

Smoke is unburnt fuel or oil, so unburnt fuel is back pressure or too much fuel injected, or worn engine, 4000hrs onwards. Depending on how used.

I would check the elbow as surgested. Getting the rubber pipe off is a problem but I did mine with it still attached.

Odysseus
Bav 38

[Yngmar]

(2) can the anode be re screwed in place without haulout and without taking the prop off?

No, not without taking the prop off, the 120S-E has a ring anode, not split and the bolts are behind the prop boss. You'd want scuba gear to take the prop cone and prop off and then replace the anode, unless you're really very good at freediving and very thorough with not dropping precious bits underwater. Or get a diver to do it.

A lose anode could jam between prop boss and saildrive leg, but you'd probably hear a scary noise when that happens.

[1simon]

Hi All,
Thanks for posting.
The attached clip shows the exhaust yesterday at2000rpm.

[Symphony]

Hi All,
Thanks for posting.
The attached clip shows the exhaust yesterday at2000rpm.

That looks quite normal. The next test (after you have fixed the anode) is whether you can reach near maximum rated rpm in flat water and a speed around 7.5 and 8 knots.

[1simon]

Hi Symphony,

Yes, I should be able to reach that speed ( 7.8knots) at 3000rpm.

Simon

[1simon]

Attached is a clip.of the exhaust last Sunday also at 2000rpm,  soon  after i had increased revs hard/suddenly to 3000rpm and motoced a lot of black smoke.

I have noticed it also sometimes whem i reverse hard.

[tckearney]

I had a similar problem a few months ago on my B42. I  heard a rattling sound when out of gear.  It reduced when in gear but I could not find the cause.  After about 1/2 mile sudden increase in revs to 3000 and a little smoke.   Also I had no drive in ahead or astern.   Sailed back to marina and tested again.  The rattle was still there but drive was fine. Lifted out and found the anode loose, both screws.  You have to remove the prop to tighten these.  I fitted a spare prop and no other problems, its been fine since ever up to 2500.  Tested the old prop in every way I could think of and can not find any fault, so never got to the bottom of the loss of drive.   The smoke I agree with all others, was just the sudden injection of fuel.