Blown Exhaust Hose - EMI Thunder Headers

[BoaterX]

Was at Elsinore today and helped out a fellow boater in distress. His exhaust hoses had torn on one side and the other side was also about to go. He's got a Merc 496Mag which he just added EMI-Thunder (http://www.eddiemarine.com/cart/details.asp?SubCategoryID=279&CategoryID=107) headers and some new muffler tips. The brand of muffler tips was something called either HYF or HYP Performance muffler tips. The exhaust tube went from the headers straight out the transom, no S brackets or anything. I can only assume they blew because there may have been too much backpressure from the muffler tips that eventually took out the weakest part of the exhaust.....the hoses. Has anyone ever seen or heard of this?? Anyone know what the cause could be?
The tips look like any other straight through tip, except it has a plate in it looking like this image below:http://216.119.68.62/ecb/video/MufflerTip.jpg

[BadKachina]

It's pretty common for an overheated motor to melt the belows off the exhaust. I would look for a bad impeller first, and if the motor got hot enough to melt the belows there could be a ton of other problems to go with it. Blown head gasket, melted wires, melted cables, all the way to destorying a complete motor.
Although, I guess it's possible for the mufflers to restrict the exhaust enough to blow the belows out but it's not something I've ever heard of.

[BoaterX]

It's pretty common for an overheated motor to melt the belows off the exhaust. I would look for a bad impeller first, and if the motor got hot enough to melt the belows there could be a ton of other problems to go with it. Blown head gasket, melted wires, melted cables, all the way to destorying a complete motor.
Although, I guess it's possible for the mufflers to restrict the exhaust enough to blow the belows out but it's not something I've ever heard of.
Hmmmm interesting.....The remaining side did look as if it were hot and was smoking. This guy was in a brand new boat.

[SnakeWrench]

EMI's need wire bound exhaust hose or they will burn out. I've heard this from a few different people. The added pressure from the mufflers would more than likely be causeing the hoses to burst prematurely. Good luck with that one.

[BoaterX]

Now that you mention it, my buddy says the exhaust hoses were MPI Soft Wall 4" Exhaust hose. He said these were cheap hoses. I couldn't tell if he was overheating though.....We tried to get his temp gauge working, but couldn't reach it and we had no tools.
On the web, also found cause for overheating could be a bad impeller or bad thermostat. Anyway, at least we have a few places to start troubleshooting.
We're heading back out to Elsinore tomorrow and this guy is camping out there with a broken boat. We're gonna try and help him out if it's a simple exhaust hose problem. It will be good to pass along the advice.