Generator exhaust puzzle

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pdecat

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My Kohler 13.5 CCOZ genny has had a leak at the turbo to exhaust mixer flange. looking at the attached picture it is obvious where it was leaking but what I cant figure out is why it looks wet and rusty. As far as I can see this is a dry joint there is no exhaust water or cooling water at that flange. Anyone have any idea where the wet stuff could be coming from?? IВґm pretty sure it is water since the metal turbo oil return line below it is rusty from where it drips on the line.
generator22009-10-16_0001.jpg
 
Hi Bruce.

Water there could only (likely) come from two places. If it is closed-cooling water (unlikely), it's probably from a crack in the turbocharger housing (very less likely is a headgasket/block crack).

Your leak is more likely to be raw water backflow from the exhaust mixing elbow (pictured).

Is your generator exhaust mixer elbow below or within 9" of the the waterline when the boat is at rest? If so, Kohler requires a siphon break a minimum of 12" above the waterline. Kohler also notes that the siphon break requires regular inspection and service to prevent corrosion from making it ineffective.

Good luck.
 
Following that line of thinking, is there any way to inspect the exhaust ports thru the exhaust manifold to see if water is getting that far back?
 
Humm, I didnt think of that but I opened the exhaust and removed the mixer and haven’t seen any water obviously near the mixer, I really dont think it was flooded and sitting in that location. There is no visible rust in the mixer just carbon. No evidence of corrosion in the turbo outlet or turbine. The mixer and the turbo outlet are dry. I cant see into the manifold because the turbo is installed. I guess it is possible that the water lift muffler fills at some point but the mixer looks dry now. I guess cooling water could be coming from the turbo but I dont see any evidence of steam inside the turbo or mixer. It is fresh water cooled with a seawater exchanger. I'll look down into the exhaust to see water level but from the level of water in the mains' sea strainers I think it is more than a foot lower than the mixer.
The exhaust hose does rise after the water lift muffle to a level above the mixer level but then slopes down so I guess it drains out since it isn’t evident in the open exhaust tube. the exhaust outlet is above the water so no siphon can happen though I guess some back flow from the exhaust tube is possible but again I didnt see any water in the engine side of the muffler.
 
Update:
I plugged the mixers water inlet and filled it with water. After a while there was some weeping at the weld under the flange using a pick I found a small hole near the weld that was plugged by carbon. Even though it didn’t go into the water jacket area there was some weeping probably from a corroded weld. Barring any other insight I think I have found the problem

generator32009-10-17_0011.jpg
 
are there any good on line parts sources? I'll bet that mixer aint cheap.
 
You can get it welded. Harbor freight has a little TIG about the size of a loaf of bread...or get a guy to come out.

If you were closer I'd bring mine and do it for you.
 
I still dont have an explaination for the cruddy flange gasket???

Thanks Charlie, we do have a guest room :) I dont think welding is a good idea since the water jacket joint is also involved and everything must be crudded up inside. After I find the price I may change my mind but it is such a PITA to remove the sound shield I dont want to do it again.
 
need a spec number there are two possible part numbers but one is $316.00 the other is $253.00 plus gaskets
 
that mixwer should be made of cast iron and if so not something that can be welded.
 
Get George the numbers if you can and he may be able to hook you up. He knows marine generators...it's his business.
 
Thanks George but I ordered P/N 256651 from the local dealer for $385. I needed some other parts as well and he had the parts book that seems hard to find on line. I should have waited a few days to see what turned up. :(
 
Hey Bruce,

Since you're gonna get a new one, How about send me the old one and I'll see if I can weld it up for you. I've already welded up/plugged the water jacket connections between the exhaust manifolds and risers using flux core nickel wire.
 
Charlie that’s a great offer. I dont know how I can really clean it though without an acid soak. I wont be in a rush but send me your address. I'm curious if you think it can be successfully welded considering the design.

George: Another boat lesson, dont be in such a damn hurry to order parts. After three days of unsucessful internet searching I gave up too soon. Thanks for trying.
 
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