Carver 440 exhaust problem

[peterrenton]

I have Cummins 475 hp engines. The exhaust is terminated through 45 degree elbows at the transom and out past the swim platform. My probelm is a tremendous amount of sooting that is accumulating both over my dinghy mounted at the rear of the swim platform and all over the stern of the boat. Has anyone ever tried extending the exhaust pipes to the rear edge of the swim platform to stop this. The engines are in tune with no issues. Any suggestions would be welcomed.

[Ramsport47]

The problem isn't the exhaust location, but the fuel you are using. It is recommended that you use a diesel fuel additive which eliminates or lessens the sooting of the exhaust. Try that first, it'll save you a lot of money on mods and cleaning

[Lyndon670]

Keep in mind that with diesels - especially turbo/inter cooled diesels, the exhaust diameter and length are designed, not just plumbed. In other words, running a longer pipe, different diameter etc - may have both short and long term impacts on your engines. Unlike gassers, "uncorking" the exhaust is a negative.

Try a better grade fuel or a fuel additive as mentioned. It may take a while to clean up, but it will definitely clean up. Also, spin your engines up to WOT and then back off 10% - will help keep your engines clean. I do this for short bursts once a week in season.

[peterrenton]

Thanks for the input. I will see what I can find for a diesel additive that will help with the problem.

[SomersDaze]

We just cleared up a similar problem on our Volvo 675s on our 570. After many other checks we just put in new turbos because they weren't getting the proper air. Spent the day on the water yesterday for our first outing with them and are finally pleased to say we were without soot for the first time in a long time.

[Lyndon670]

Was there many hours on your Volvos? That's bizarre that BOTH turbos were bad - beyond bizarre when you look at the reliability of the Volvo design.

[SomersDaze]

No. Only 550... It was bizarre but we had several mechanics look at them and perform every other option to no avail. The boat was hardly used the 10 years before we took it. Thus little maintenance was done. The lack of use has been the brunt of all our issues. The entire aft... Entire ... would be covered in soot even more so when the wind was behind us. But it is fixed and we are thrilled!

[Lyndon670]

Wow, still shocked. My 2001 506 had only 290hrs on it when I got it this winter, the previous owner had passed away and it was left to his elderly parents 2006 - so the hours were delivery hours, spring run up and winterization. It was never used after his demise, but I have no soot from my Volvos. But, they maintained it with an open cheque book. I am up to 430 now with no issues.

[jnick]

What additive have you been using for a cleaner burn? I just recently started having this same soot issue. Funny it started after taking on about 400 gallons of fuel from our local and reputable dealer.

[avtech001]

Just as a side note .....I have seen boaters pull fuel off the bottom of the tank that for some reason had something in it that caused the above described issue, a lot of sooting from both engines