Exhaust Risers

I am getting my exhaust risers rebuilt and the builder has offered to have them ceramic coated for a couple hundred bucks. Intuitively this seems to make sense as it would cut down on the potential for rust, that is unless the ceramic cracks and allows for the entry of water.

Anyone have experience with this? Worth the money and time?

Gordon

I have had new SS risers ceramic coated when new and then inspected them regularly over a longer period of time and I had very good results. I do not know what the implication is of coating a riser that has been in use. Getting the ceramic coating into the areas that have serviceable issues for your application is always a task.
I took digital pictures at various times to use as benchmarks and review their condition.

Smitty477,

Unless I am mistaken, my risers will be new. When I say rebuilt, I mean built new from scratch using my existing risers as a pattern. The current ones are 13 years old and don't think there is anything I want to keep.

How long have you had yours and do you have any evidence that they are outlasting normal stainless 316 uncoated?

Gordon

"How long have you had yours and do you have any evidence that they are outlasting normal stainless 316 uncoated?"


- 8 seasons so far in salt water at about 1,000 nmiles per season and just over 100 hours each engine.
- I have had similar risers on very similar engines in similar boats but did not have the ceramic coating. On past applications I have used SS risers and CuNi risers so I am comparing those experiences with these.
- As a rule I take off one riser every other year for inspection (alternating) , after taking some pics I remove the carbon and get a better feel for any etching or pitting and take some more pics.


This has been my experiences with simple swept risers that I am very happy with - YMMV

Does that riser/mixer drain completely when the engine is shut down. Or does it leave a pocket of water in the jacket near the turbo outlet to sit there and corrode it from the inside. It isn't obvious from the pic.

Looking all the way to the right at the 4 O'clock position you can just see a fitting that delivers water to the packing gland.
That fitting completely drains these risers when the engines are not running.
There is almost zero corrosion in that area after 8 seasons.

I wondered what that was. Interesting solution to the self draining problem. But be sure that the hose to the packing gland doesn't have any dips so it will fully drain.


Are you a boatdiesel member? If so how about posting that pic and see what the pros say. I have never seen this solution discussed on boatdiesel. If not, is it ok if I post it there?


David

"But be sure that the hose to the packing gland doesn't have any dips so it will fully drain."


They are almost a straight run down to the gland - I have checked that run on this boat and past boats which were very similar and there was never a blockage at the gland of within the line. By playing with the line "on and off' right after and during operation you can see that it drains within seconds of engine "off". Between this boat and my last 3 I have just about 25 years with this set up.



"Are you a boatdiesel member?"
I was for a dozen years or so but I am not currently - if you want to copy the picture be my guest - I have maybe 2 dozen shots of the inside of these risers somewhere around home. I had brought that particular riser home to insect carefully after last season and could see quite well all around inside with bright flashlights and a snake camera in some areas even with my 'older' eyes.


FWIW - this is a typical set up on many Bayliner with diesels and is similar with all their models and engines in this range - 32, 34, 36, 37, 38 , 39, 45 and 47. There were more than a few thousand boats like this and it has been an active topic at times on the Baylinerowners club over the past 20+ years. I have never heard of a problem at the BOC with either the original cast iron risers or any of the aftermarket SS risers due to these drain lines - quite the contrary.