496 Mag Bravo 3 Hesitate-Vibrate-Clunk

[Blitzn]

Good evening,
First – I have tried to look at the other postings on Bravo 3 Outdrives for similar items and reviewed what I found. Not finding one that matched – if I missed one, I’ll apologize in advance if this is duplicated.
Summary of my normal maintenance – boat is stored inside storage with full fuel tanks over winter. Oil changed and gear lube replaced last fall as well as new batteries this spring (Optima Blue top). 2009 496 Mag with Bravo 3 OD with about 80 hours on it.
Last fall, we used it right to end of season – and the marina pulled it before I got there on Saturday, and racked it away into heated indoor storage. They said they filled the fuel tank and Stablized it (cannot verify).
This spring she had a hard time starting and ran really ragged. Excessive vibration shook the entire boat (love watching the forward deck bounce up and down – not!). Once warm – this goes away not to return until next cold start.
Last outing was perfect. Tonight – really hesitated until really warm – bad fuel? Would not get on plane for repeated attempts until nearly half hour. Then another new experience – nearing higher end (35mph or higher load) would hear clunking sounds coming from the engine/OD. Difficult to identify exact location while driving. At dock – I revved the throttle idle and received no similar sounds.

Summary of issue:
Running rich - nearly double gph burn
hesitating
vibration
clunking noise nearing top end
no WOT
Horrible acceleration

So – discussing with dockhands – first off I’ll add octane booster and see if that helps. Fuel degradation could indeed be an issue. Next, perhaps some fuel stabilizer since it sometimes is a week or two between uses.
Thought I might have my mechanic take a look – since he did the gear lube.
What’s your ideas on other items to consider?
Thank you,
-Dennis

 

[skibum]

I think the initial rough start was probably because they fogged the engine, and you just needed to burn the plugs clean. They may still be slightly fouled. I'd pull them and take a look before knocking myself out chasing other issues. I'd also run it until most of the fuel was gone and top it off with some fresh fuel before doing any other troubleshooting. I don't think you are dealing with a big problem.

 

[Henry Boyd]

I'll echo Skibum's comment on plugs, and go a step farther. I only go two seasons on a set of plugs, regardless of hours. For us the winter lay ups and preparatory fogging degrade them to the point of no return after the second season.

There are a number of posts giving part numbers for the plugs, so you can buy the same plug at places like Napa or Autozone at a much lower price.

Henry


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[scoflaw]

They may have improperly fogged your engine, like shooting fogging oil directly into the throttle body, contaminating some of your sensors. Does this boat have an O2 sensor ?

 

[rondds]

How old are your plugs? 8.1s are notoriously tough on plugs, then add in the mess that fogging can create. You ain't getting 100K miles on them. Agree with the others and look to replace them first.

Good point by scoflaw - ask how exactly they fogged. I'd HOPE that a mechanic would know to not squirt fogging spray into the throttle body but I wouldn't be surprised...

 

[Blitzn]

Thank you for the comments so far. Replacing plugs is an easy (and sadly fun for me) chore - so that's a good item. I failed to mention the boat is kept in heated indoor storage over the winter so fogging has not been performed since I started doing that.

 

[Henry Boyd]

Not to shift gears on you, but you might think about fogging the engine. It still is going to sit for several months and trapped moisture and products of combustion will take their toll regardless of the storage temperature.

Henry

 

[scoflaw]

Not to shift gears on you, but you might think about fogging the engine. It still is going to sit for several months and trapped moisture and products of combustion will take their toll regardless of the storage temperature.

Henry

Pure myth

You can't prove that fogging your engine is preserving it, making it last longer.

I can prove that not fogging for a 6 month layup has no detrimental effects what so ever, year after year.

 

[Henry Boyd]

Pure myth

You can't prove that fogging your engine is preserving it, making it last longer.

I can prove that not fogging for a 6 month layup has no detrimental effects what so ever, year after year.

I don't have to. Chemistry and metallurgy pretty much speaks for itself.

Ok, now make your case.


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[techmitch]

I don't have to. Chemistry and metallurgy pretty much speaks for itself.

Ok, now make your case.


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Thank You!

 

[dpvandy01]

I'm with Henry on this one. Moisture and metal only make ONE thing. Rust. And rust in cylinders only makes one thing,,, problems

 

[Blitzn]

Ok. Thanks. I'll discuss that.
Spoke with my mechanic and he's looking at it tomorrow. This weekend I'll tackle plugs and such and let you know.

 

[MExcelsior]

I'm assuming this engine is an mpi? You didn't get any alarms? If that's the case, Henry is right as fogging an mpi incorrectly can trash a very expensive fuel delivery system. Nothing is normal about any of this with an mpi and repeated attempts at anything is a bad idea. Get it in to do a computer diagnostic.

 

[scoflaw]

Here's my point about not fogging a fuel injected engine

Whatever your using in your cocktail , whether it be 2 stroke oil or marvel mystery oil, neither of those are fogging oils. Neither have the ability to cling to bare metal any better than the motor oil that's already on those parts. If in fact they do, why would 2 stroke owners bother with fogging their engines ?

My 11 year old engines sit on the hard for 6 months or so. Both run perfectly up to 5K rpm's and don't use a drop of oil in the 6 months it sits in the water. Now then if parts were getting rusty would I not be experiencing some running issues ?

Another thing that can be done is remove your drive belt for the winter, and disconnect your fuel pump. Every month or 2 spin the engine up with the starter for 5 seconds or so.

 

[Henry Boyd]

Here's my point about not fogging a fuel injected engine

Whatever your using in your cocktail , whether it be 2 stroke oil or marvel mystery oil, neither of those are fogging oils. Neither have the ability to cling to bare metal any better than the motor oil that's already on those parts. If in fact they do, why would 2 stroke owners bother with fogging their engines ?

My 11 year old engines sit on the hard for 6 months or so. Both run perfectly up to 5K rpm's and don't use a drop of oil in the 6 months it sits in the water. Now then if parts were getting rusty would I not be experiencing some running issues ?

Another thing that can be done is remove your drive belt for the winter, and disconnect your fuel pump. Every month or 2 spin the engine up with the starter for 5 seconds or so.

You are correct about the stickiness of 2 cycle, or basic engine oil. But fogging oil is "sticky" as anyone can attest who has handled stuff coated with it. Since we are talking a four cycle engine, there should be no oil present above the piston rings. There however will be carbon and other products of combustion (including H2O) that combine and create an acidic environment. Again since it is a four stroke, several of the exhaust valves will be open exposing those cylinders to atmosphere via the exhaust system. Since the 496 exhaust was installed without flapper gates (per Sea Ray's specification with Merc), that means a direct line to the outside.

I can't answer your question, other than to point out that it is one person's experience, and that the science does not support your position for a broader population. I'd also point out its not "if" the internal parts are rusting because they are, the question is; At what point does the amount of corrosion have a negative impact? Over the years I have had a number of sports cars, as well as boats that have been stored over the winter. I can unfortunately recount just how much damage a rust stuck piston ring that breaks can create on the first start up of the spring. For me whatever the added cost of fogging oil and proper engine winterization is is peanuts compared to the cost of potentially having to replace a piston and machine the cylinder wall of the engine.

While effective, I'm not sure I get the economics of your alternative plan. I mean disconnect the fuel pump, as well as the batteries (pre-supposes you are not in a boat yard that requires batteries to be removed during lay up, or that is your personal preference), spin the engine and then reconnect everything in the spring. Isn't a can of fogging oil cheaper and simpler?

But hey, its a gamble. And to quote Dirty Harry Callahan, "Do you feel lucky today".

Henry

 

[Woody]

You are correct about the stickiness of 2 cycle, or basic engine oil. But fogging oil is "sticky" as anyone can attest who has handled stuff coated with it. Since we are talking a four cycle engine, there should be no oil present above the piston rings. There however will be carbon and other products of combustion (including H2O) that combine and create an acidic environment. Again since it is a four stroke, several of the exhaust valves will be open exposing those cylinders to atmosphere via the exhaust system. Since the 496 exhaust was installed without flapper gates (per Sea Ray's specification with Merc), that means a direct line to the outside.

I can't answer your question, other than to point out that it is one person's experience, and that the science does not support your position for a broader population. I'd also point out its not "if" the internal parts are rusting because they are, the question is; At what point does the amount of corrosion have a negative impact? Over the years I have had a number of sports cars, as well as boats that have been stored over the winter. I can unfortunately recount just how much damage a rust stuck piston ring that breaks can create on the first start up of the spring. For me whatever the added cost of fogging oil and proper engine winterization is is peanuts compared to the cost of potentially having to replace a piston and machine the cylinder wall of the engine.

While effective, I'm not sure I get the economics of your alternative plan. I mean disconnect the fuel pump, as well as the batteries (pre-supposes you are not in a boat yard that requires batteries to be removed during lay up, or that is your personal preference), spin the engine and then reconnect everything in the spring. Isn't a can of fogging oil cheaper and simpler?

But hey, its a gamble. And to quote Dirty Harry Callahan, "Do you feel lucky today".

Henry

Probably even worse for those exposed to salt air.

 

[scoflaw]

You make reference to sticky fogging oil. But that's not what your fogging your MPI with. The cocktail is diluting it and merc recommends 2 stroke oil, which isn't a whole lot of protection.

Piston rings have been made of molybdenum for some time now, days of cast iron rings are long gone. That moly isn't going to stick. Batterys stay connected, and plugged into shore power. Hit the starter and let it spin, quick and easy. If there was a way to introduce real fogging oil thru the induction system I would be all over it. I guess I've just been real lucky for a really long time. LOL.

 

[aerobat77]

i,m not saying not to fog if you like to do , but can tell you i have never fogged an engine over winter and i never had any issues with not doing it .

 

[kap2]

I have an MPI and use fogging spray via the spark plugs then turn the motor over to get the fogging oil to spread throughout the chamber. Pulling the plugs isn't much labor for the insurance.

 

[rondds]

Only problem there ^^^^ is that it doesn't coat the valves and seats.