Lots of soot

[tsouthard91]

Transom area has lots of soot as of this season.

Wondering if this is an issue?

[Big Block Power]

How many times have you ran it this year.

[tsouthard91]

Close to 12. Maybe more.

[cmattj]

Question. Just a few
Do you have captains call exhaust?
Do you run high octane fuel above 87?
Have you been stern in (parked) at a gathering?
Have you checked your trim resv or outdrive fluid levels to see if they are loosing fluid.?
And lastly ...has any engine work been performed this year , or are you experiencing any off idle hesitation?

Pics are helpful as sometimes water scum lines can be confused with soot. I know.... I boat in a swamp

[Big Block Power]

Yea without a scanner or engine data is hard to say. That would be a rich condition. Is the coolant sensor reading cold. Tstat working right. Get the mercury vessel view? Is it that bad. Much worse then last year.

[tsouthard91]

Hey guys,

So answers to the questions:
- Yes I have CC exhaust
- Run Premium Ethanol Free only.
- Yes, I have been parked at a gathering but I don't think that is the issues
- Trim and outdrive fluids are good.
- I have had the oil changed on the engine but that is it.

My initial thought is that it is running rich.

[cmattj]

Remember these systems run rich for the environment there in of your era.
So let’s try just changing a few things first before we have our injectors balance tested, and scanned by a Dealer.

Use 87 octane (91 isn’t required and has a slow burn off threshold. Long story).
Flip your CC off whenever your backing in or idle in confined areas.
And lastly. Apply some polymer wax & sealant ( i use bio- Kleen) to your transom and water line edge on the sides.
You’ll be surprised how with these small steps your visual soot will lessen .
Keep us posted as I’m glad to hear your at least not seaping oils.

[tsouthard91]

Thanks Matt. I will give these a shot.

I am hesitant to run 87 as I only have access to the ethanol version of that.

[NautiGirl]

Flip your CC off whenever your backing in or idle in confined areas.

Nope, CC on when pulling into a cove. Have to announce your arrival. Showing off is worth the effort of cleaning some soot off the boat.

[cmattj]

Thanks Matt. I will give these a shot.

I am hesitant to run 87 as I only have access to the ethanol version of that.

I was as well....
My last boat , and my current have twin 496 with CC. The change to 87 octane is going to be probably the biggest factor in reducing soot on the transom.
Look for 10-15% percent ethanol in a 87 and you will be fine. You have a lot of outings anyway so it’s not an issue.

Last tank of the year fill her up with your non ethanol blend.

[ajcampen]

Use a marine stabilizer with the fuel

[tsouthard91]

Thanks guys.

I appreciate it!

I agree with you Nauti...have to let people know you have arrived.

[akorcovelos]

Flip your CC off whenever your backing in or idle in confined areas.

Nope, CC on when pulling into a cove. Have to announce your arrival. Showing off is worth the effort of cleaning some soot off the boat.

this 100%.

FWIW when I switched to premium my soot went down to almost nothing, though that could be the retune as well.

[Southerncomfort]

Thanks Matt. I will give these a shot.

I am hesitant to run 87 as I only have access to the ethanol version of that.

I was as well....
My last boat , and my current have twin 496 with CC. The change to 87 octane is going to be probably the biggest factor in reducing soot on the transom.
Look for 10-15% percent ethanol in a 87 and you will be fine. You have a lot of outings anyway so it’s not an issue.

Last tank of the year fill her up with your non ethanol blend.

Matt, so you run 87 in your twins currently?

I am running 89 during the year and put 93 in when putting her up in storage for the winter, with fuel stablizer added just for good measure.

Oh and agree with Nauti, turning captain's call off is not an option.

[cmattj]

Matt, so you run 87 in your twins currently?

I am running 89 during the year and put 93 in when putting her up in storage for the winter, with fuel stabilizer added just for good measure.

Oh and agree with Nauti, turning captain's call off is not an option.

Hey Southern.
Yes... Been doing it for the last year , and it has reduced transom soot for me.

I used to worry about one engine sensing ping or knock, and reducing the timing just on that one engine during that key cycle. But then I made the change and went to 87. I have scanned both engines after running the 87 fuel and have not had a timing reduction event in either of them. (the ecu will make a timing map change automatically). So she likes the 87 Octane as it can be expected she would.

As we have discussed in other threads higher octane rating is increasing the engine ability to resist knock or ping during the combustion process. The trade off is an obviously a less explosive combustion in the cylinder, thus resulting in lower power level.
Any 4 stroke gasoline combustion engine will make the most cylinder expansion power right to the very point of a ping or knock . By increasing your octane level on an engine that doesn't ping currently you will effectively reduce the power of the cylinders thermal combustion.

Oh and since they all run rich anyway for the lugging marine world environment, and only a few models require 91octane.. Enjoy the 87