Why would this do this?

[beamons]

I am looking at a new boat and it is out of state but I am wondering if anyone knows if this is normal or something to be concerned about. What causes the discoloration on the top of the Catanium exhaust headers.

[NautiqueJeff]

Looks to me like it got hot. Not sure though.

[wtrskrs]

I am looking at a new boat and it is out of state but I am wondering if anyone knows if this is normal or something to be concerned about. What causes the discoloration on the top of the Catanium exhaust headers.

I'll ask some folks tomorrow at the pond that have them; I agree overheating, perhaps caused by an impeller going out. If that is the case and the cats got that hot, I'd be concerned about the engine (warped heads, etc.). Then again, maybe that's not the case. Don't know what that does the the converters; they need heat to work, but don't know what happens when there's too much heat. BTW, what boat? You can't beat the wake on your 98. If I was doing a lot of tourneys I might consider repowering mine to get Zero Off. But Zbox is good enough for me (but I digress from the topic....)

[Nautiquehunter]

I have a 08 with a Catanium 343 with over 1000 hours it does not have any discoloration on the cats.

[Evening Shade]

They have been hot for sure. Happened to my 2011 210. Bought it used from a dealer. Supposedly had a new impeller and all fluids changed before I bought it. I test drove the boat and everything was great. 5 hours later when I put the boat in my lake it over heated. I wasn't used to the link screen and couldn't find the temp gauge. It was throwing a code on the screen that I didn't understand. I assumed it couldn't be overheating because I just test drove the boat that same day. But that's what it was. I was sorta distracted trying to figure everything out on the helm since it was so different than my Malibu and even though I was just idling it got hot enough the boil the antifreeze. The silver paint on my cats turned brown. I felt like such a dam* idiot.

[Infinity]

Yep, that boat was overheated for sure, question is how hot did it get to discolor it like that and what potential issues could come down the road because of it. Would raise some red flags/questions for me that I would want answers too. My guess is that eventually the discolored areas will start rusting since the coating has been compromised. I have the catanium ZR409 and have no discoloration, heat is only thing that will cause that.

What model/year boat, how many hours, etc?

Quick story. I went out last Spring on a 2017 Supra right after dealer had done impeller change for the owner and it overheated when we were like 2 miles away from dock before it happened cause he started up and took off right away. The owner decided to start dumping cold water on the engine risers, then would run it toward dock till it started beeping again near 190 degrees.....shut it down and dump more water on it and then run it again, the rubber hoses were literally smoking a couple times cause of how hot it got without water to cool the engine risers/hoses. Was crazy, I would never do something like that to my boat and would have much rathered sit out there for 2hrs than watch someone else do that to boat engine! After 30-40 mins, owner limped it back to the dock. Dealer's mechanic met us at dock, replaced the impeller in about 20mins and then we went out again for the rest of the day without issue. (when dealer installed the 1st impeller, they had not tightened the cover properly and due to air leak it didn't seal and cause the overheat). When I change impeller, I always start the boat, check for leaks and water flow and let the boat get to temp and hold a few mins in the driveway to be sure its all good for this exact reason.

My point is that you should ask questions about this and get a copy of the maintenance log/history on boat. It could have been something innocent that caused the overheat, obviously sometimes you can do things right (pay dealer to replace impeller and it isn't done right) and still have an issue.....Depending on the owner tho, do you let the dealer bring a boat and come to you, or do you risk the engine and do what the above guy did cause your time is more important than potential damage to the boat engine?

This may not be the case....but seeing your picture, I would have to wonder if the owner was not the type to maintain things. Was oil/filter changed every 50hrs, etc. How does the rest of the boat look inside and out? If its out of State and you can't personally check compression and run lake tests, I would pay the money to have it checked out. To much money to spend to find out you bought a boat that was not maintained like it should be. Multiple times I have seen newer boats that are the same year, one looks immaculate and obviously cared for and the other looks obviously neglected and years older than the other due to that fact.

[Infinity]

Got me curious as too the potential damage something like this could cause, so did a google search. Obviously, the resulting damage depends on how hot it got and how long it was run after the overheat started along with some other factors.
Hopefully it wasn't a major overheat but you have to calculate into purchase price the fact that even if it wasn't, the discoloration wont go away and will also effect your resale value down the road and raise questions if its an educated buyer like yourself.
When did the overheat happen....was it recent which makes you wonder if that is partially why the boat is being sold and maybe some issues are coming up, was it 2yrs ago and there have been no issues since?
Again, to me looking at the entire boat inside/out also tells you something about how it was cared for and maintained. If everything else looks perfect, maybe this was just a freak occurrence that was unavoidable for one reason or the other. If other issues are found or boat looks neglected, then to me its likely that owner just wanted a boat to have fun on and the rest of the time didn't give it much thought. Those are the kind of boats I would avoid like the plague, only a small percentage of total boat owners spend time on the forums when we are not having a current issue. Most owners know nothing about their boat and don't care to take the time or spend the money to properly maintain it, its simply another toy to be used and thot about only when its convenient for them.

This link is interesting, course it focuses on salt water boats....but talks about how corrosion or improper maintenance of the exhaust risers can cause issues. Worst case is engine failure if water gets into cylinders. Doubtful that is the case here, but knowledge is power.
https://www.yachtsurvey.com/exhaust_risers.htm

This thread talks about an overheat on a inboard engine (5.7 Mercruiser). If you read down a ways, his risers got hot enough to melt some of the electrical wire jackets.....so that is another thing to carefully check out and make sure didn't happen, if it did, those risers got WAY too hot. I know on my boat, some plug wires touch the risers and there are also some electrical wires that run thru engine area under the cover and next to the catanium risers.
Also, in this thread, some of the rubber exhaust hoses had damage which could be checked by removing them and looking at inside for blistering, etc.
https://forums.iboats.com/forum/engi...er-overheating