Hunter 28.5 2GM20 exhaust soot in bilge

[inkunzi]

My 1988 Hunter 28.5 with the 2GM20 engine has black sooty water collecting in the bilge. I also have clean exhaust water collecting under the engine. As far as i can tell the exhaust elbow is not cracked. This is a freshwater boat. the exhaust hoses look original I’m thinking: f it replace the muffler and hoses and exhaust elbow in one shot. I’ve seen posts where the exhaust muffler and fuel tank had some kind of incestuous relationship and exhaust water was getting into the fuel tank. Apparently Hunter had some kind of deal To replace the fuel tank with a plastic one?? Mine looks plastic. Also saw a post where the partition between the engine compartment and the starboard lazarette was removed to facilitate access to exhaust elbow. This will be a fall project on the hard. do I need to replace stock muffler? is there a super duper replacement to be had? Near as i can tell the existing muffler looks like a black kettle

 

[Ralph Johnstone]

I'm sorry but your post appears to be one contradiction after another. Could you please answer the following questions so we can help you help yourself :

has black sooty water collecting in the bilge.

What evidence do you have this is exhaust water ? Pictures please.

I also have clean exhaust water collecting under the engine.

What evidence do you have this is exhaust water as opposed to lake cooling water ?

As far as I can tell the exhaust elbow is not cracked.

What have you done to determine if it's leaking or not. If I checked it during operation, it is either leaking or it's NOT leaking. It's not "as far as I can tell" it's not leaking. Pull the elbow and inspect it AFTER you have wrapped it in paper towel. NO, not on the extremely hot riser as there's no water there. Onhte cooled portion.

I’ve seen posts where the exhaust muffler and fuel tank had some kind of incestuous relationship and exhaust water was getting into the fuel tank.

And I've heard that some guy in Kalamazoo has built a perpetual motion machine.
This is crap from the internet and you should be able to determine by your own inspection that there is no way exhaust water could to get into your fuel tank. Unless the engine exhaust line is connected to the fuel tank vent line ? ? ? ? Maybe ?

Also saw a post where the partition between the engine compartment and the starboard lazarette was removed to facilitate access to exhaust elbow.

Are you saying you are having trouble accessing your exhaust mixing elbow ? Is this the reason you are unable to determine if the elbow is leaking ? Pictures and an explanation may go far to helping you with this problem.

do I need to replace stock muffler?

Is there anything wrong with the existing muffler ? If it's leaking, by all means replace it as it's a source of carbon monoxide. If it's based on this idea that the exhaust system is somehow putting exhaust gasses and water into the fuel tank, maybe not the best idea I've ever heard. Maybe save your money for something more useful like investing in the guy with the perpetual motion machine.

 

[Tally Ho]

I would start the engine and inspect the exhaust path for leaks….maybe the rubber hose is cracked somewhere and this is not as big of a deal as you think. Maybe not even exhaust water at all. Be aware of CO and ventilate the area if possible.

My O’Day 322 (1988) has the same engine. I removed my plastic water-lift muffler once and it had nasty water in it…if the muffler is leaking, that could be the source. But I would think you could find the leak if you inspect with the engine on and water flowing through the system. I have never changed my exhaust elbow (although it is on the list) on my fresh water boat.

I have never heard of the exhaust and fuel tank being ”conjoined”.

On my Hunter 280, there was a panel at the back of the aft berth that could be removed to access the fuel tank and other equipment. Mine was just held in place with screws.

At this point, investigation is your mission…and take photos so we can see what you are dealing with. It certainly helps us understand your situation better.

Greg

 

[inkunzi]

Thank you Ralph Johnston for your reply. Harsh, but useful in my continuing search for perfection on this old boat. Note: its original name was ALOPY where the previous owner managed to only erase the J. The soot in
the bilge is carbon black and seems to be washing into the relatively small bilge from under the floorboards..it only appears after running the engine. The Clearwater leak is indeed lake water. Both of these are manageable no big deal. Have not detected any exhaust smell so CO is not a concern at this time. Apparently, earlier (1985 to ?) versions of this boat did have a problem with exhaust water getting into fuel tank- go figure. Hunter had a retrofit plastic tank available to correct the problem.
I’m assuming that this black soot is coming from some sort of exhaust system leak and would make sense that it would come from the muffler where the exhaust/water mix has solids sinking to the bottom then slowly leaking from a cracked muffler. My thinking is replace the whole system as long as I have everything pulled apart with a new muffler and hoses and anything else that be currently at fault or on the verge of being at fault ..So im fishing for responses that may provide that one small clue or bit of info that makes addressing the issue more achievable. Since I’ve already purchased one of those perpetual motion machines I figure one is enough and i would rather spend a couple of bucks on redoing entire exhaust as opposed to doing it on piece at a time based on the age of this Yanmar 2GM20F system. Again thanks for the help

 

[Davidasailor26]

If you’re getting sooty water in the bilge how can you tell that you’re also getting clear water? If you are that suggests you have two separate leaks. Are you sure the clear water is from the engine at all, and not a different source like a thru hull or rainwater?

If the exhaust hose is original from 1988 it doesn’t owe you anything so if it would make you more comfortable go ahead and replace it. Whether that will fix your problem is still unknown. You’re right that one possible source of the sooty water is the muffler. But before replacing that I’d look for more evidence that it’s leaking and try to trace things down better.

The water in the fuel tank situation sounds odd. I could imagine that an exhaust leak would leave water under a metal tank and corrode the bottom, but that would usually put diesel in the bilge and not water in the tank. A leak on top of the tank could maybe corrode the top, but still that putting water in the tank would be pretty unusual. Maybe @Crazy Dave Condon has some recollection of the history, but in any case it sounds immaterial to your current problems since you’ve got the plastic tank.