Exhaust restriction

[HahnR]

Hello all,

I got a call from our engine mechanic today. All long stories aside, the starboard engine has not been run since December of last year. He just completed an overhaul of that engine and was planning on breaking it in today. However, raw water and exhaust will not exit the boat so there is obviously a restriction in the muffler or exhaust somewhere. I'm suspecting some sort of critter has set up a residence in the exhaust somewhere, he thinks a baffle might have come loose in the muffler. Are there baffles in the mufflers & if so what are the chances one came loose? It's in a '78 Series I 58 MY, 8V92 Ti dry exhaust. Mufflers and exhaust all appears to be factory. Unfortunately I am 1200 miles away from the boat or I would be there right now. He wants to get a diver to shine a light up the exhaust, my coaxing couldn't get him to lay on the swim platform with a light and mirror. Has anyone run into this before?

Thanks,
Randy

 

[Boatsb]

Ive installed a ball in the exhaust to keep it from sinking the boat before pulling the manifolds and risers. Did someone do that?

If not maybe there is a new resident in the boat. Try to catch it. In the south most them critters is good eatin.

 

[SEVEN]

I know this is a dumb question but did he flip on the intake water thru hull? If so is water coming in?

 

[HahnR]

Thanks Scott & Rusty. We didn't put anything in the exhaust, although now I'm thinking we should have. He texted me tonight he got it figured out. I'll wait to hear in the morning now to see what he found

 

[SEVEN]

Let us know your findings.

 

[HahnR]

All is well. Here's the story: The starboard engine was torn down in early August. We visited the boat over Labor Day weekend and were greeted with a good 4" to 5" list to port, due to the weight removed from the starboard engine. Unfortunately we were then blessed with the opportunity to Hurricane prep the boat for the chance of a Cat 3 - 5 Irma making direct landfall where the boat is located (Savannah, Ga.). At least that was what they were harping on the whole week, so better safe than sorry. All loose items were secured & stowed as low as possible in the boat, much of them forward. Add to that a spare starter, 30 gal of oil on the starboard side of the generator room, a couple hundred pounds of ground tackle in the starboard deck box, the starboard engine reassembled & we were left with a bow down starboard list. Even though the exhaust at the transom was half out of the water, this allowed the exhaust to the muffler to fill with enough water the exhaust pressure from the engine at idle couldn't overcome the backpressure. The mechanic moved enough stuff around to level the boat as much as possible, & the problem went away. Lesson learned, always look for the simplest things first, and be aware that what you do to compensate for one thing will always affect something else at some point.

I just wish these lessons weren't so expensive. I can't wait to get this old girl home where I can personally keep an eye on her and do most of the wrenching myself. The good thing, she made it through Irma unscathed without a scratch on her.

 

[kelpy]

Something isn't right here. A DD 8-92 starting up will have absolutely no trouble at all in clearing out a muffler, and the rest of the exhaust system, that is full of water. It will shoot it 20 feet out behind the boat. Even a 4-71 will shoot the water slug 15 feet.

 

[HahnR]

I was wondering about that too. I wish I could have been there to see it in person. Unfortunately I'm just going by what he told me he experienced. He is very particular, maybe he wasn't happy with the volume of water exiting the boat & suspected there was a restriction. Tomorrow is the engine break-in day, I will be in regular contact with him & get some further clarification. At this point, I am just really glad I don't have something else to fix.

 

[SEVEN]

Easy yet lucky fix. Make sure you keep your eyes the water flow and temperatures. Be quick to shut her down if the heat climbs. Good luck. $$$$$$

 

[Pete]

I was wondering about that too. I wish I could have been there to see it in person. Unfortunately I'm just going by what he told me he experienced. He is very particular, maybe he wasn't happy with the volume of water exiting the boat & suspected there was a restriction. Tomorrow is the engine break-in day, I will be in regular contact with him & get some further clarification. At this point, I am just really glad I don't have something else to fix.

I second what your mechanic is relating based on personal experience with a 453. Why this happens is a detailed discussion.

Pete