2005 Mainship 400 exhaust hose replacement

[Timmyvan]

So we have a new to us 2005 Mainship 400 with a Cummins 5.9 and are working through our list of needed repairs. The 1st one is to replace the 11' long, 6" exhaust hose from the engine to the muffler. The existing 1 has cracked where the hose does a 30 degree turn, And our surveyor recommended that we replace it. We have the new and expensive hose in hand, and can remove the old hose With a bit of muscle and hacksaw work. But we are struggling with how we can install the new hose. Not having any experience with this, This seems like a difficult task to push the hose on to one of the nipples, bend the hose, and then try to get the other end onto the Engine nipple. The hose is 6" hard wall and not Very flexible. We are hesitant to pull off the old hose until we can figure out how to install the new. Pictures attached. Any assistance is appreciated. The 3rd photo shows the crack at the turn. I posted this elsewhere and got lots of advice, like heat hose, lube hose, prebend hose, put a fiberglass elbow at the bend, etc. but none who actually has done this project.

 

[Dougcole]

I replaced the exhaust hoses on our 2005 400 twin about a year and a half ago. It's a harder job with twins as the access to the port muffler is behind the generator and is VERY hard to reach. A mechanic quoted me $5K to do that job and said he would need to pull the genset, but I managed to squirm behind the genset and get it done. The 6" hose on the single will be harder to work with than the 4" hose on twins, but your access is much better.



It's a physically hard job, but not mentally challenging. The hardest part is getting the old hose off. Heat helps with that as does sliding a screw driver and/or hose removal tool inside the hose around the flange on the muffler and exhaust elbow. On the port side I cut the hose inside the ER then drilled a hole through both sides of the hose, slid a 2' long piece of rebar through the holes and used it to twist the hose off. I didn't have to do that on the stb side as access to the muffler is so much better.


Installation is a two person job as one person pushes from the ER side and the other lines up the hose on the muffler. I didn't have to use heat for the install, just a little dish soap.



The advice you have gotten from others seems good to me. It doesn't look like an elbow is warranted at the bend to me, but others on here, like Ski and Rich Gano are much more knowledgeable than me and will likely give you better advice on that.


One thing, and I hate to tell you this as they are expensive, but now would be a good time to consider replacing the exhaust elbow and mixer if they have not already been done. Take a good look at them anyway.


Just dive in and get started. You can do it and it's not something that you can mess up really, it's just dirty hard work.