Lets Talk Soot

[OldSchoolBoats]

Brand new rebuilt motor, got about 17 hours on it now.

Motor builder says run 91, so I run 91 from Campbell's or Shell along with adding Stabil Marine 360 at every fuel up.

Cleaning this every single morning is getting super annoying.

Any suggestions??

Would some turn down mufflers help?? The exhaust is straight pipe.

 

[hallett21]

Brand new rebuilt motor, got about 17 hours on it now.

Motor builder says run 91, so I run 91 from Campbell's or Shell along with adding Stabil Marine 360 at every fuel up.

Cleaning this every single morning is getting super annoying.

Any suggestions??

Would some turn down mufflers help?? The exhaust is straight pipe.


View attachment 1357098 View attachment 1357099

It’s a 525 right?

 

[OldSchoolBoats]

It’s a 525 right?

Yeah

 

[Mandelon]

Muffler extensions?

Wax the hell out of that transom too. It should clean up easier.

 

[Ace in the Hole]

Brand new rebuilt motor, got about 17 hours on it now.

Motor builder says run 91, so I run 91 from Campbell's or Shell along with adding Stabil Marine 360 at every fuel up.

Cleaning this every single morning is getting super annoying.

Any suggestions??

Would some turn down mufflers help?? The exhaust is straight pipe.


View attachment 1357098 View attachment 1357099

91 makes my 520 have a lot of soot….it gets the cheap shit per merc specs after figuring that out. It was never anything close to that bad though….

That is EXCESSIVE imo..

 

[OldSchoolBoats]

91 makes my 520 have a lot of soot….it gets the cheap shit per merc specs after figuring that out.

That is EXCESSIVE imo..

87 or 91 and still the same. Builder says run 91 so that's what I am doing.

 

[Ziggy]

Boy, to me that says running rich. Only time I've had any was with a huge load of humans and the throttled pinned.

 

[Ace in the Hole]

87 or 91 and still the same. Builder says run 91 so that's what I am doing.

That’s excessive so…rich condition? It’s not oily at all is it? How do your pipes look under the flapper?

 

[OldSchoolBoats]

Muffler extensions?

Wax the hell out of that transom too. It should clean up easier.

Boat is ceramic coated. It cleans up with Xtreme Transom Mist and wet rags, but literally adds 15 mins to my wipe down program.

 

[Cooter01]

Maybe a different tune from someone? That seems excessive

 

[JFMFG]

Running way rich.

 

[DWC]

That’s a ton of soot. Our Magic/496 would have quite a bit more running 91 VS 87. Nowhere near that though. Yikes.

 

[Angler]

Pull a couple of spark plugs and take a look.

 

[OldSchoolBoats]

Maybe a different tune from someone? That seems excessive

That was my thought. Was considering sending the PCM out.

 

[OldSchoolBoats]

That’s excessive so…rich condition? It’s not oily at all is it? How do your pipes look under the flapper?

I didn't check but the soot seems oily when cleaning off but that may be from the cleaner......lol

 

[Cooter01]

That was my thought. Was considering sending the PCM out.

I would look at the plugs too, any way you can do a datalog or have someone local tune it? Any smoke at idle? Does it smell rich or anything? Any trouble starting cold or hot?

 

[Done-it-again]

I wonder if the PCM is thinking you are running in high altitude. That’s crazy

 

[Chili Palmer]

Adam’s tire and wheel cleaner works great on transom soot.

 

[Dcb.blake]

I feel the pain with the soot. Such a pita to clean regardless of the process or if it has wax/ceramic. I battled it for a while.

For sure running rich. I would check plugs and make sure they look good and are the correct ones. If the tune has been altered from factory I would look into that as well.

Was it a factory rebuild back with stock stuff or was there some modifications for performance?

 

[PRIMO]

Had the same problem on my Magic Deck Boat
with a 525 Merc / Put a set of Splitfire Plugs in
for a wider spark and it worked wonders / No more soot

 

[Racey]

How does the oil smell, that looks very rich

 

[monkeyswrench]

I wonder if the PCM is thinking you are running in high altitude. That’s crazy

I'd think the PCM would lean it out at altitude for air density. Don't know anything about the Merc ECM's, but she's definitely fat. Not good for a fresh motor.

 

[CSmith]

I have had that happen to my boat. Result was to much oil. You aren't over full are you?

 

[Mandelon]

21 posts and what? Hello???

Have you tried a different prop?


You're all slipping....

 

[Happy Smitty]

Looks like it spent a day in the channel during a holiday weekend.

 

[OldSchoolBoats]

I would look at the plugs too, any way you can do a datalog or have someone local tune it? Any smoke at idle? Does it smell rich or anything? Any trouble starting cold or hot?

Smells normal to me and starts up fine. No smoke or anything.

 

[OldSchoolBoats]

I feel the pain with the soot. Such a pita to clean regardless of the process or if it has wax/ceramic. I battled it for a while.

For sure running rich. I would check plugs and make sure they look good and are the correct ones. If the tune has been altered from factory I would look into that as well.

Was it a factory rebuild back with stock stuff or was there some modifications for performance?

I will have to see if I can find the build sheet, it's in my previous build thread. We didn't add any HP or anything from what I know.

 

[shintoooo]

 

[77charger]

Running way too rich. May need retune. Don’t think extensions will help either as the exhaust will still be trapped under the steps.

 

[BUDMAN]

I would take it to a different shop and let them diagnose it.

 

[BingerFang]

Running way too rich. I would send these pics to the engine builder before I took it anywhere else.

 

[4Waters]

Running way too rich. I would send these pics to the engine builder before I took it anywhere else.

^^^^this^^^^

Injected or carburetor

 

[n2otoofast4u]

^^^^this^^^^

Injected or carburetor

It’s injected 525 factory Merc deal.

@OldSchoolBoats do you know if he had the injectors cleaned/flowed while it was apart? Does the fuel economy seem significantly worse than before?

 

[02HoWaRd26]

Yeah

To be honest try 87°! My boat was always sooty when i saw before i bought, guy said he was told 91° so that’s what i ran, then i went to 87° as per many many others as well Mercury’s website and soot was gone.

 

[DaytonaBabe]

An outboard would fix this issue immediately.


You're welcome!

 

[JB in so cal]

An outboard would fix this issue immediately.


You're welcome!

 

[Livewire Fabworks]

Brand new rebuilt motor, got about 17 hours on it now.

Motor builder says run 91, so I run 91 from Campbell's or Shell along with adding Stabil Marine 360 at every fuel up.

Cleaning this every single morning is getting super annoying.

Any suggestions??

Would some turn down mufflers help?? The exhaust is straight pipe.


View attachment 1357098 View attachment 1357099

Jesus dude, that is horrible. As mentioned that thing is running super rich! That thing looks like your rolling coal. Did they clean the injectors when they rebuilt it?

 

[fishing fool]

Running way too rich. I would send these pics to the engine builder before I took it anywhere else.

^^^^this^^^^

Injected or carburetor

Talk to engine builder about a tune,

I'm no engine guy but if you run it too rich won't you wipe out the rings?

 

[OldSchoolBoats]

It’s injected 525 factory Merc deal.

@OldSchoolBoats do you know if he had the injectors cleaned/flowed while it was apart? Does the fuel economy seem significantly worse than before?

Not sure, I will ask him. Already chatting he says it could be a few different things. Fuel economy seems about the same. It's definitely thirsty though and we run really easy for the most part (40-45 MPH and under 4k RPM).

 

[SummitKarl]

yea that is a rich mixture, unless those plugs are tan 3/4 of the way down the ground strap it's rich. This was typical back in the day of the Merc 496HO when people would put 91 in a motor designed for 87, allot has to do with the piston and the head chamber for a complete burn and it's easy to mess up ie.. open chamber vs. closed chamber require different pistons to get a complete burn, either way 100% you are not burning all of what goes into the cylinders. Another thing to watch out for if carbureted is the stock style fuel pump I have seen those fail and dump gas right into the oil pan (check your oil level), once running and warmed up pull a breather off a valve cover and see if it is spitting out oil/smoke at idle that will tell you if the rings didn't seat on your new build

 

[Bpracing1127]

Put a blower on it and it won’t be rich anymore

 

[Chili Palmer]

As it’s been said before, on my 496HO running 87 over 91 will keep the transom clean, but when I do a lot of ski pulling I do seem to get a lot of soot on the transom even running 87.

 

[OCMerrill]

If this condition stays around long enough you run the risk of unburnt fuel wash down. Basically wash the oil off the piston skirts.
Its deeper than just keeping the transom clean.

Running a little rich is protectionary but that is fat fat fat. Injector issues? Timing issues? Fuel Pressure issues?

 

[Ace in the Hole]

If this condition stays around long enough you run the risk of unburnt fuel wash down. Basically wash the oil off the piston skirts.
Its deeper than just keeping the transom clean.

Running a little rich is protectionary but that is fat fat fat. Injector issues? Timing issues? Fuel Pressure issues?

Was circling back to this thread to question this....

 

[NicPaus]

I run 91 majority of the time in my 496ho and barely any soot. Something else is going on. Saw Matt this last week out in the old Howard. Thinking you miss it even more dealing with this. Hope you get it figured out at no cost.

 

[Todd Mohr]

I had way more than normal soot on my transom this weekend, I know different animal my 2.5’s. Maybe the cool temps? Should be leaner with cool air, boat ran great but way dirtier transom than normal.

 

[HST4ME]

What the operating temp? For whatever reason was the thermostat removed?

 

[02HoWaRd26]

I run 91 majority of the time in my 496ho and barely any soot. Something else is going on. Saw Matt this last week out in the old Howard. Thinking you miss it even more dealing with this. Hope you get it figured out at no cost.

You’re not helping your engine or power running 91° you’re actually wasting money as the 496 cannot burn that fuel off. So you’re getting worse economy as well spending $0.30-0.50 more per gallon.

Mercury does a ton of research and they know better than cousin Bill or the dude that lives next door to your best friend. It’s all on their website.

 

[Ziggy]

Did you have any soot buildup with the old motor? Could the Stabil be adding to it if you're adding it at every fill?

 

[NicPaus]

You’re not helping your engine or power running 91° you’re actually wasting money as the 496 cannot burn that fuel off. So you’re getting worse economy as well spending $0.30-0.50 more per gallon.

Mercury does a ton of research and they know better than cousin Bill or the dude that lives next door to your best friend. It’s all on their website.

Our pump at Echo is 91. Wasting a lot of money at $7 a gallon compared to in town. But towing to town ads 2 hours or so.

I topped off at pirates this last week at $6. Slowest pumps ever. But gas was from last year so figured a little 91 in each tank to freshen it up. And the 87 pump was broke.