Sign of something wrong?

[Dpmmvc]

Is the rust stain or what appears to be rust stain in these pictures around telltale a sign of something bad?

[rbk]

Yup, time for a new exhaust pipe.

[Uncle Bob]

Originally Posted by Dpmmvc

Is the rust stain or what appears to be rust stain in these pictures around telltale a sign of something bad?

Hi, does your engine have a cast iron exhaust elbow by any chance? Looks like a rust stain from either an iron elbow or a raw water cooled engine.

[Dpmmvc]

Engine is fresh water cooled. I believe the exhaust elbow is cast iron yes.

[RaymondR]

Not necessarily. It could mean that the fitting just need removing, cleaned up and rebedded. SS will rust if water is retained in a crack as it relies upon a supply of oxygen to form the protective layer on the steel. Generally called crevice corrosion.

[Uncle Bob]

Originally Posted by Dpmmvc

Engine is fresh water cooled. I believe the exhaust elbow is cast iron yes.

As Raymond has said, just take the elbow off the engine, thoroughly clean and descale it and reinstall with appropriate bedding material. The stain on the transom will buff right off.

[Dpmmvc]

Happy New Year everyone! Correct me if I’m wrong but it sounds like worse case scenario I’ll need a new elbow and best case just clean the inside of elbow out..? I know where the elbow connects to the manifold the bolts look in decent shape (minor surface rust) so I don’t think it will be a problem to remove and do one of the two

[ebs001]

Originally Posted by Dpmmvc

Is the rust stain or what appears to be rust stain in these pictures around telltale a sign of something bad?

I had a Catalina 36 and the exhaust did not come out through the transom. If I'm not mistaken that is the drain for the cockpit scuppers. If so the stain is from standing water in the pipes.

[Boatyarddog]

Originally Posted by Dpmmvc

Engine is fresh water cooled. I believe the exhaust elbow is cast iron yes.

If your in San Diego, unless in a river, your engine cooling loop is two part.
That is, your raw water loop, the raw water pump drawing water into your heat exchanger, then out thru your Exaust riser and out of the vessel.
And your engine loop(aka"fresh water") circulation loop of Antifreeze, and the other half of your heat exchanger.

So, you probably have salt water coming out of your Exaust, of course this can stain your gel coat.
As well maybe a sign of rusty up stream components worth looking into.
Exaust Riser, inline couplers,Exaust thru hulls of SS, won't happen with bronze components, associated fasteners of poor quality.
SV Cloud Duster

[JPA Cate]

Remove rust stains with oxalic acid. You can buy the crystals as brick cleaner, and mix your own solution according to the instructions. The source of the rust could be from an iron exhaust elbow, or just the interaction of sea water and s/s. You can remove the rust from the s/s, either chemically (as above) or with scouring powder and a sponge. You can try waxing it (car polish), but I never found it lasted very long. Mostly i just scritch my spotty s/s with a scritcher sponge, like i use to wash dishes with.

Ann

[Mike Banks]

If your boat is fibreglass, it is not a biggie. Of it is plywood it needs some further investigation. It looks to me as though you have some corrosion inside you exhaust system, probably caused by seawater cooling of the manifold. Mostly the exhaust elbows are of stainless steel but sometimes they are cast iron, which is ok--but they do produce the effect your pictures show.

Clean off the rust stains with CLR or some other cleaner.