Mercruiser Mag 350 300hp/bravo 3

matt13

matt13

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I did do a search on this but only found posts from 2005 which said there were a few problems with the outdrive. I just wondered if anyone knew if this was still the case and wether they are a good pairing. Only ever owned a boat with a 150 outboard before so not too clued up on the engine and outdrive situation. The boat I am looking at now is 2008.
 
No problems with this combination, its when it was paired with a Yanmar 6cyl diesel that the drive gave problems due to the high torque from these motors. petrol engines have completely different torque characteristics and these drives work just fine with Mercruiser petrols, my mate has a Wellcraft running a 330hp 7.4ltr V8 on an Alpha I drive and its given no problems and I have a Magnum 350 on an Alpha drive which is been running since 1997 so a 350 on a Bravo III drive will be fine, just make sure its been serviced properly as no drive will survive neglect.
 
spannerman said:
No problems with this combination, its when it was paired with a Yanmar 6cyl diesel that the drive gave problems due to the high torque from these motors. petrol engines have completely different torque characteristics and these drives work just fine with Mercruiser petrols, my mate has a Wellcraft running a 330hp 7.4ltr V8 on an Alpha I drive and its given no problems and I have a Magnum 350 on an Alpha drive which is been running since 1997 so a 350 on a Bravo III drive will be fine, just make sure its been serviced properly as no drive will survive neglect.
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Thanks that's put my mind at rest somewhat. I will be keepin it on the hard anyway so will help with longevity.
 
matt13 said:
That's what I had heard but I'm sure I read somewhere that they tried to sort it with the later versions. I could of course be completely wrong.
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you're right but what I'm not sure of is what year was it sorted and more accurately, what serial numbers to watch out for on the drives to be assured you've not got a duffer
 
matt13 said:
The boat I am looking at now is 2008.
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In this case, the drive should be the latest style, with the curved profile on its back side, as in the pic below.
I would second everything spannermann said.
Normally mated with big blocks, it's bound to be bulletproof on "just" a 5.7 engine, if properly serviced.
Which boat? Pics?
bravo3_large.jpg
 
Bravo 3 drives don't have the exhaust at cavitation plate like Volvo Penta outdrives. They discharge the water and exhaust gases from transom.

So while on plane since the upper gear is out of water it starts to overheat and then when came off plane hot upper gear touches to water and the black coating starts to flake off. This increases the corrossion issue.

Volvo penta outdrives have the exhaust at the cavitation plate and even on plane the upper gear is out of water it doesn't overheats since it is cooled by the sea water passes through the leg.

This is (very) common problem in USA, people installs drive showers to cool down the upper gear on plane.

Also there is a litte filler tank (like coolant expansion tank)on Mercruiser engines to top off the drive oil. Because when the drive overheats it looses some oil in certain time and this leads to wear in upper gear components of drive.

I don't know why Merc don't produce legs like Volvo penta or VP have the patent of the through leg discharhe/exhaust.

Hope this hepls.

Best regards.
Melida
 
oGaryo said:
you're right but what I'm not sure of is what year was it sorted and more accurately, what serial numbers to watch out for on the drives to be assured you've not got a duffer
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some info here but as these guys sell the things putting the onus on the customer makes me think twice about taking the advice i.e. wouold they admit to selling a dodgy product?

http://www.sterndrives.com/bravo_3_corrosion.html
 
Melida said:
Bravo 3 drives don't have the exhaust at cavitation plate like Volvo Penta outdrives.
They discharge the water and exhaust gases from transom.
...
Hope this hepls.
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That doesn't help at all I'm afraid, because it's not correct.
Bravos discharge water through the propeller, and even if/when installed with straight thru transom exhaust, that does not create, per se, any cooling problem.
It's true that on some boats with straight exhaust someone fit outdrive showers, but that's because these boats are frequently pushed very hard, and sometimes with engines with more than stock power (thanks to blowers or other tricks).
And those boats have B I rather than B III drives, anyway.
There's a simple reason why in those conditions you will never hear of a VP outdrive failing, and that's because nobody use it for such applications! :)
 
MapisM said:
That doesn't help at all I'm afraid, because it's not correct.
Bravos discharge water through the propeller, and even if/when installed with straight thru transom exhaust, that does not create, per se, any cooling problem.
It's true that on some boats with straight exhaust someone fit outdrive showers, but that's because these boats are frequently pushed very hard, and sometimes with engines with more than stock power (thanks to blowers or other tricks).
And those boats have B I rather than B III drives, anyway.
There's a simple reason why in those conditions you will never hear of a VP outdrive failing, and that's because nobody use it for such applications! :)
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Haha,
Please read carefully what I wrote.
The transom exhaust I mentioned is the outlet just below the transom shield which is an integrarated part of it.
Can you explain me why the drive oil dissapears in bravos and no decreaesing amount of oil in Vp legs?
Search forum sites of USA, you can see lots of GAS(benzyne) Mercruiser 5,0, 350Mag, 6.2, 7.4 and 8.1 or 496Mag powered boats suffer this.
Hope VolvoPaul chime in and would better explain then me why VP legs are better than Mercs.
 
Melida said:
Haha,
Please read carefully what I wrote.
Click to expand...
I did.
You wrote that Bravo "discharge the water and exhaust gases from transom", and if you insist that this is correct, sorry but I'm not wasting time answering your other questions.
 
MapisM said:
I did.
You wrote that Bravo "discharge the water and exhaust gases from transom", and if you insist that this is correct, sorry but I'm not wasting time answering your other questions.
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Well done to you.
Now you can waste your precious time with corrosion issues of bravo3 if you have it.
 
Let's not get personal here! The important question is what boat and how fast? Am I going
to need to get aviator re mapped to keep up??
 
z1ppy said:
Let's not get personal here! The important question is what boat and how fast? Am I going
to need to get aviator re mapped to keep up??
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Z1ppy I think you will be safe! the only way I'm keeping up with you is if you are towing me!

Anyway I'm not interested in which is better Volvo or merc as it is not an option I need to worry about. Just need to know if there is a serial no or something I should look out for. Mapism thanks for the photo. The boat is a 26' sports cruiser 5.7ltr 300hp. I will be keeping her on the dry stack so am hoping if the outdrive hasn't corroded away already this will help IF corrosion is an issue on this model.
 
matt13 said:
I did do a search on this but only found posts from 2005 which said there were a few problems with the outdrive. I just wondered if anyone knew if this was still the case and wether they are a good pairing. Only ever owned a boat with a 150 outboard before so not too clued up on the engine and outdrive situation. The boat I am looking at now is 2008.
Click to expand...

Hi Matt.

I've run a Mag350 & B111 combination for 5 years now. I've had no problems other than a UJ bellow leak and ruin a Gimbal bearing.

I've not suffered from corrosion issues even though she's kept in the water, BUT I am careful when I swap my anodes.

As for the overheat/exhaust issue, not had a problem. My B111 has a low pressure exhaust in the shield and at higher revs also vents through the prop. I have the exhaust bellows fitted on mine but some have a tube which reduces back pressure when the boat is on the plane and the leg is trimed out slightly.

To answer your question you have nothing to worry about...... no more than any other sterndrive system.

Good luck


Paul.
 
paultallett said:
Hi Matt.

I've run a Mag350 & B111 combination for 5 years now. I've had no problems other than a UJ bellow leak and ruin a Gimbal bearing.

I've not suffered from corrosion issues even though she's kept in the water, BUT I am careful when I swap my anodes.

As for the overheat/exhaust issue, not had a problem. My B111 has a low pressure exhaust in the shield and at higher revs also vents through the prop. I have the exhaust bellows fitted on mine but some have a tube which reduces back pressure when the boat is on the plane and the leg is trimed out slightly.

To answer your question you have nothing to worry about...... no more than any other sterndrive system.

Good luck


Paul.
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Cheers Paul!
 
matt13 said:
Mapism thanks for the photo. The boat is a 26' sports cruiser 5.7ltr 300hp. I will be keeping her on the dry stack so am hoping if the outdrive hasn't corroded away already this will help IF corrosion is an issue on this model.
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You're welcome, 'twas actually just a pic linked from Mercury website.

Dry stack will definitely help increase the longevity, and not just of the outdrive. Even more so if you will also flush the engine with freshwater after using the boat.
In this respect, one convenient feature of Bravo (as opposed to Alpha) is that the water pump is on the engine, not inside the drive. This means that you can arrange a convenient flushing connection by fitting a T valve on the hose which goes from the outdrive to the engine.
And by leaving it close while the boat is stored, you will keep the water inside the circuit, rather than allow it to slowly drain back through the outdrive (just remember to re-open the valve after the boat hits the water, and before turning on the engine!).
With this trick, the pump impeller will never run dry, as it normally happens when restarting the engine after the boat has been dry stacked.

Good luck with your new toy!
 
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