I also melted an exhaust hose a couple of weeks ago for no apparent reason. I changed the hose and back flushed the coolers and have ran about 10 hrs now with no issues. I am running an old style set of Imco Powerflows that have had the tails cut off about 10" from the elbow and about 12" of rubber hose.

Here is my question. I am considering welding 4" stainless tubing to my existing tails all the way to the tips and joining the pipe to the tips with just a short rubber coupler. If I do this, should I also lengthen the inner pipe? All the way to the tips? Will this help with reversion, I am getting ready to install a bigger engine. I don't expect to have any reversion issues, but you never know. Where is the best place to mix the water with the exhaust?

Thanks

I am also considering extending the inner pipe several inches. I have been studying the reversion issue alot because I am building some bigger engines for my scarab, as I understand the principle you will still have reversion but the further back where the water enters into the exhaust flow the better you are because the distance of the reversion "wave" that has water will have to travel before it enters the exhaust port in the head go reversion info here;

http://www.boatheaders.com/reversion.htm


Cliff

After reading that article, i believe the best thing to do would be lengthen the inner pipe as long as possible. Any other opinions? These are angled down Bravo style.

I think I would try and get to the bottom of why the hose is melting. It has to be getting hot enough somewhere to melt this and it doesn't happen under normal conditions. Putting stainless tubing in will not melt the hose but it will still be getting hot somewhere.

The rubber hose is melting because there is not an even flow of water through it. Any rubber hose, even the high temp blue silicon stuff will melt if placed directly in the path of the hot exhaust gas, the water flow is what cools it.

Either your rubber hose is not lined up correctly or there is a restriction in the water flow from the risers. I had this issue with my last exhaust up-grade, I put a rubber coupler on the end of the riser, a length of stainless tube, a small section of blue high heat silicon rubber tubing connected to the tail pipes. This way you can slightly change the angle from the riser to the tail pipes so it is a "straight-shot" all the way along the pipes so you get even water distribution inside the pipe.

Good luck with it.....

I agree, I would find the cooling water supply or distribution problem before moving this problem downstream. Otherwise check the transom material, I have seen these "light up".

Is the rubber hose strait out of the riser and intot he tip with no bends? If there is a bend from the riser into the hose the hose will get got in one spont and melt. everything has to be very strait.

This exhaust is strait as a string. It ate an impeller about 2 weeks before it burnt through, and I suspect it had a piece of rubber stuck in the oil cooler or somewhere. It burnt through while idling about 15 minutes waiting on an idiot at the ramp. I think just the low water volume while idling combined with a possible small blockage did it in. I believe that i have the problem corrected.

It just seems to me that SS tubing would be a better option than rubber hose under normal circumstances and if so then I would like to do it correctly.

i ran into this with my old 454 when i put dana's on it, the water did not come out of the riser the whole diameter of the 4" pipe and had "hot spots" as well, first attempt was puting 6 inch long stainless sleeves inside the rubber hose but they tend to slide back when everything is heated up, final fix was using the hose as a coupler and used 4" stainless pipe cut from riser to tip, problem solved

Did you by any chance loose an water pump impeller before your problems started. Seen this happen when all the small impeller parts were not found and restricting water flow.