One of my headers turned blue on 500 efi????
 

After I pulled the boat out of the water I noticed I had a header that had gotten extremely hot. It turned it blue and purple and melted the little decal on the header. At first I was thinking it ran lean on the left bank but realized it still should have not got hot on the outer header. So, I am assuming I have a water flow issue. I have not checked the water pump impeller yet. I also have a sea strainer on the boat so i wouldnt think i should have any blockages. Any ideas or advice is appreciated.

Check all your water hoses on that side. disconnect and backflush. You may also have a leak in that pipe, not unheard of.

Wannabe

Lack of water flow=Blue header

+1,, suspect impeller or the hose at the tramsom os plugged..could also still have impeller blades lodged in the oil cooler if someone did a impeller swap..

Once you figure out why it's not getting water, you can buff it out, and it will look like new. You may want to get it pressure checked to make sure there are no internal cracks.

A few years back, I was running wide open in some rough water, and blew off the water supply hose. Header got so hot it melted the rubber hose connecting the header to the tip. Then it caught on fire! I about sh*t my pants. Halon system didn't go off. Probably because I raised the hatch. Luckily it just went out on its own in a few seconds. Now always carry 2 extra fire extinguishers. There was hardly anyone on the water that day, and I was making some long wide open runs. I railed past some water po po and they were watching me with the binoculars. We had our life jackets on and no booze yet so wasn't too worried. After I had my problem, the smoke pouring out of the engine hatch looked like a forest fire. Probably the only time in my life that I was hoping the po po might come help me out. Not a chance. lol

One side hot one side cold think for a second! Was your op temp Ok when running? If so it is without doubt an issue only on that side, if it were an impeller or collapsed hose both sides would be hot. You need to check flow into and out of that side!

I checked flow on both sides, appeared to be the same. Impeller looked good but I went ahead and replaced. I also back flushed all the oil coolers. Polished off the blue and ran it this weekend, I checked it a few times and it never seemed to get hot. Maybe it temporarily sucked some mud and caused it to happen last time...???