Bravo 3 overheating - oil expansion

[DIY1111]

I believe I've assessed that my 2003 Bravo 3 drive with 1100 hours ( I've had engine and drive since new - so I know how she performs ) has an overheating issue. I've noticed that after running over 4000 rpm's that the drive oil reservoir level will rise considerably - even overflow over time. Under 3200 RPM's, my normal range of use, the rise ( expansion from heat ) of oil is negligible. Noticed that the top of the drive[s antifouling is blistered a bit. The drive oil removed from season was perfect - green and 'purty.

(2) years ago, due to a slow oil leak, I had competent mechanic inspect drive. Said the bearings had lost pre-load - he replaced the top U joint shaft assembly, O-rings and seals. Said bearings and gears fine. Pressure check - fine.

I noticed that after pulling the drive this year that when spinning the U joint that ( while out of gear ), it feels grindy - meaning, it feels tight - I feel like I can feel the bearings spin. This might be normal but figured I'd mention.

I'm trying to get this before it is a major issue.

Where should my main focus be ?

 

[alldodge]

The drive lube bottle cap is most likely your issue. The cap has a one way valve which allows air in but not out. The B3 does generates more heat then other Bravos and with the expansion the lube does increase IF the valve does not operate correctly. The classic symptom is the bottle over fills and dumps lube in the bilge.

 

[DIY1111]

That would be an easy fix and would love for it to be so !

I understand what you're saying - but, I can't see how that small rubber valve in the cap would prevent expanding oil from going where it wants to -= small rubber valve be damned I see how it might be engineered to allow air to in and out as the oil expands and contracts normally. I've filled my reservoir up over the years, sometimes over the 'max line' and never have had this happen. Only over the past few years ( I'd like to time it since the top U joint was redone ) that the oil has expanded like this. Even if I have it below the max line, when I go over approx 4000 RPM's she can and will blow over. And, there is the blistering paint on the top of the drive ( I know this is out of the water, but it's a relatively new things to happen )

Replacing the cap is easy enough. I just don't want to do this, put her in in the Spring to find this is still ocurring. If there is a problem, I'd like to nail it now. Any way to test the theory out while dry docked and pickled for them winter ?

Thank you !

 

[alldodge]

Google Mercruiser gear lube bottle over flow.

So far as a test, I have not given it any thought. Maybe remove the bottle and attach a hand vacuum pump to show when vacuum is pumped the valve opens. Then with a bicycle pump and gauge, pump it up to 5 psi to see if it holds. Watch the bottle to see if it expands. Don't know how much pressure the bottle will hold

 

[DIY1111]

Google Mercruiser gear lube bottle over flow.

So far as a test, I have not given it any thought. Maybe remove the bottle and attach a hand vacuum pump to show when vacuum is pumped the valve opens. Then with a bicycle pump and gauge, pump it up to 5 psi to see if it holds. Watch the bottle to see if it expands. Don't know how much pressure the bottle will hold

Google Mercruiser gear lube bottle over flow.

So far as a test, I have not given it any thought. Maybe remove the bottle and attach a hand vacuum pump to show when vacuum is pumped the valve opens. Then with a bicycle pump and gauge, pump it up to 5 psi to see if it holds. Watch the bottle to see if it expands. Don't know how much pressure the bottle will hold

In your opinion, the drive should not be suspect ? I have read a lot about the overflowing Bravo 3 drive reservoir - there's info about the cap but also the possibility of something heating up internally, for example a bearing , enough to expand the drive fluid to the levels I'm talking about. I would love to take the easy route here, but do not want to err and find my drive issue become really expensive due to an adjustment or worn bearing.

If you were me, what would you do ?

 

[alldodge]

If you were me, what would you do ?

I would drain the lube and if it looked just like it went in (no darker, green and all that) I would replace the bottle. Its $50 bucks but the drive cost more.

If you have a buddy with a Merc lube bottle, exchange caps with him/her

 

[metsfan3197843]

Mod Edit - No!

 

[metsfan3197843]

My bad, thought we were trying to help each other out on here.

 

[alldodge]

My bad, thought we were trying to help each other out on here.

Tis never the season
Use PM

 

[GA_Boater]

My bad, thought we were trying to help each other out on here.

We do, but only using the proper methods.

Sorry for the interruption, DIY1111.

 

[DIY1111]

We do, but only using the proper methods.

Sorry for the interruption, DIY1111.

Thank you all for your help. I returned a PM to metsfan - like everyone, he's trying to be super helpful.

I wonder - what is the life expectancy of a Bravo 3 with light/ moderate use ?

 

[alldodge]

Depends on load but if well maintained (yearly changes with proper lube), I see of no reason to ever fail

 

[DIY1111]

Depends on load but if well maintained (yearly changes with proper lube), I see of no reason to ever fail

Music to my ears. That’s my goal !

 

[Lou C]

The Bravo series are known as stout drives, the main thing on the BIII is avoiding corrosion on the lower unit due to the large twin stainless props. With proper maintenance (drive pull each season, oil change each season, checking for water in the gear oil and fixing things as they come up) no reason why an outdrive can't last the life of the boat. Using the right gear oil is important, in this case the Merc High Performance gear lube (bluish/green stuff)
Mine's 32 years old! And all salt water use, moored in the salt 6 months out of each season 15+ years since I've owned it. But every year the maintenance was done, and things were fixed (seals) when needed.

 

[tpenfield]

I have about 1100 hours on my twin Bravo 3 outdrives. Rarely, if ever, have I gone over 4K RPM. 2500 - 3200 is the typical engine speed at which I run.

If you have run the outdrive to the point that it gets hot as you described, then you should assume that there has been more wear. Having to adjust the pre-load on the upper gear set would be a sign of wear. If you are feeling grinding as you turn the outdrive, then you might want to consider some re-building in the near future.

U-joints, even in poor condition, do not always 'feel' rough. So, be sure to verify where the grinding is coming from (U-joints, or upper gear set). Replacing the U-joints is probably a good step and will eliminate 1 of the 2 possibilities. If you still have grinding, then you know where to look next.

As AD mentioned, Bravo outdrives can take a lot of usage (and even some abuse) and live to tell about it. Alphas tend to give it up after a good life, particularly if they have been driven hard.

You do, however, see the go-fast crowd replacing Bravo outdrives fairly often, as they typically run them in the 4-5K RPM range 'all day long' sort of thing.

 

[DIY1111]

I have about 1100 hours on my twin Bravo 3 outdrives. Rarely, if ever, have I gone over 4K RPM. 2500 - 3200 is the typical engine speed at which I run.

If you have run the outdrive to the point that it gets hot as you described, then you should assume that there has been more wear. Having to adjust the pre-load on the upper gear set would be a sign of wear. If you are feeling grinding as you turn the outdrive, then you might want to consider some re-building in the near future.

U-joints, even in poor condition, do not always 'feel' rough. So, be sure to verify where the grinding is coming from (U-joints, or upper gear set). Replacing the U-joints is probably a good step and will eliminate 1 of the 2 possibilities. If you still have grinding, then you know where to look next.

As AD mentioned, Bravo outdrives can take a lot of usage (and even some abuse) and live to tell about it. Alphas tend to give it up after a good life, particularly if they have been driven hard.

You do, however, see the go-fast crowd replacing Bravo outdrives fairly often, as they typically run them in the 4-5K RPM range 'all day long' sort of thing.

Thanks for the replies ! I have maintained all since new - dropped drive each year, inspected oil, replaced gaskets/ rings etc. I have almost no electrolysis and I'm in the brine 7 months a year ( I spend many hours in Spring properly prepping drive for primer and antifouling - SS tabs are epoxied and antifouled to reduce high-noblility metals in the water ). If something is even marginal, I replace it. I like to be proactive, not reactive, that's why I want to get this now.

Top U joints are new, less than 100 hours. The slight 'grind' feels like when you over-tighten bearings - you can feel them move as opposed to them moving freely, i.e. like on an older car when you tighten front wheel bearings too much, you can feel it when you spin the brake drum ( sorry, I have an old VW beetle. - best analogy I can give ).

As for abuse - none. I'm pushing a 23' deep V hull, my 350/ 300 and the Bravo 3 are more than enough. As mentioned previously, if hooked up to a computer, it would show outside if idling out of canal, engine has spent 95% of its life at 3200 RPM's or less.

Hardest thing for me is to find a trustworthy, talented Mercruiser mechanic on Long Island, NY. My mechanic of many years flaked out on me this year... Looking for someone who is proud of being honest and who does top notch work.

 

[tpenfield]

Maybe too much pre-load of the drive shaft bearing . . .

 

[alldodge]

Hardest thing for me is to find a trustworthy, talented Mercruiser mechanic on Long Island, NY. My mechanic of many years flaked out on me this year... Looking for someone who is proud of being honest and who does top notch work.

I had same issue so I bought the tools to rebuild my own.

Ask the question on Offshore Only. There are some there in NY, and many others ship drives to All American drive in Chicago
https://www.allamericandriveservice.com/

 

[DIY1111]

I'm back. I have been to Offshore Only - minimal recommendations - one good lead - the guy retired.

Anyone have personal experience with East Shore Marine - Lindenhurst, or Pearl Grey in Amityville ?

Thx