2015 PCM ZR409 - Exhaust Manifolds - Overheating

You should probably take the shotgun approach and post this question everywhere you can think off and give a little more info too 

Does a Centurion have the same instrumentation and alarm package that CC had that year?

What happens to your engine in this "limp mode" ?

I really think it is just a matter of keeping the exhaust manifolds free of the flaking debris, for whatever reason several of us that use our boats a lot exclusively at our lake are having the same issue. Our lake has around 1,000 ppm of dissolved solids in addition we have a lot of very fine sediment.

I plan to drain the exhaust manifolds more often and will see if I can run some fresh water through the system from time to time, hopefully this works. If not I will have to pull it out of the water and have Jonny look at it closer.

There's also the Red "check gauges" indicator for engine related issues

I'd probably be talking to a Centurion dealer because it doesn't seem logical at all to go into a limp or protective mode without some indicator or horn being activated

Not going above idle is more of a "crawl home gasping for your last breath" mode than the typical limp mode.

The only thing flowing through them is exhaust gas with a water jacket around the gas side.

I think the derate starts at 220 degrees and if it keeps going up to 225 it derates more.

Have you checked the manifold temps with an IR gun?

If it was my boat, I'd be finding out more about the protective system and instrumentation, but it's not my boat, ....... it's your boat . A dealer or PCM can tell you something

What are the guys with the other boats with the same problem doing?

I have not checked the manifolds with a IR gun. The two times they have overheated you could smell them and when I dripped water on them from my wet gloves it would quickly boil off.

A 2015 ish 200 with a 6.0 just had the manifolds and a few other parts replaced for $6k, a 2008 196 with a 5.7 had the manifolds replaced as well for a much more reasonable cost. Other owners are draining/cleaning them out like me. I heard one owner took his to the car wash and shoved the power wash wand up the drain plug hole in and attempt to clean. The owner with the 196 just bought some starbright descaling engine flush he is going to try.

I have talked to a few PCM dealers and they are not helping much, they say bring it in and if we can duplicate it we might be able to fix it.

No garden hose attachment for back flushing on my boat currently but may put one on to run fresh water through the system from time to time.