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08 MCX Exhaust -- how hot is too hot?

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  • 08 MCX Exhaust -- how hot is too hot?

    Did maiden voyage today on our 08 X1, just tooling around getting some hours on engine.

    Noticed that the exhaust hoses connecting the ETX/CATs to the exhuast tips get REALLY hot when at speed (3000 rpm). Realizing that the Cat's will run hotter than tradional exhausts, but:

    - too hot by far to hold hand on by connection to manifold,
    - hot enough to make exhast hose soft and collapsible,
    - hot enough to smell like burnt rubber.

    Is this normal ?!

    Other circulating hoses seemed fine, engine running normal temp. Thanks.


    One side even kinked a bit from getting soft from the heat:

    Last edited by fbroen; 03-23-2008, 09:36 PM.

  • #2
    I noticed on the '07 X-2 we had, that it also got very hot. Gauge read normal, but when you popped the engine compartment you knew it had to be way warmer than what it was reading. I never really looked that close to mine to see if it was bending.

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    • #3
      I don't think there would be any issues, exhaust is going to be hot.. come on, it's comming out of a engine.. just make sure the water injection is working.
      2017 Mastercraft XT21- Black & Calypso Green Flake and Coolfeel interior

      2008 Mastercraft 40th Anniversary X-star SOLD

      1981 J-craft 19 long deck ski boat w/200 Mercury Black Max (the gas guzzler)

      2018 Audi Q7 Technik Navarra Blue with S-Line, Black Optics, Luxury package, advanced driver assistance, Audi Sport 21" wheels, tow hitch

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      • #4
        Water temp wont have much indication on how how the exhaust is getting. Exhaust temp can run up to 1200 deg. before melt down give or take 50. this is temp should be taken about 2" out of the Exhust port on the mainifold take a temp gun and shot it and I bet its not over 900 deg.

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        • #5
          Most every V-Drive boat I have ever see on the production line @ MC has a kink in the rubber pipe between the exhaust manifold/muffler/thru hull exhaust fitting, because of the angle of the approach. Until a form fitting metal or fiberglass pipe with a radius is used with a short rubber joint each end, there may be a kink in those hoses I would guess. Apparently MC engineering/Indmar doesn't think it hinders the performance. Maybe someone from the MC factory can elaborate on this. Is it done like that by other boat manufacturers.
          Last edited by TMCNo1; 03-24-2008, 07:41 AM.
          Charter Member Number 1

          Quote: 2RLAKE,
          At some point in time people need to wake up, remove their cranial intrusion into their own rectal areas, and take responsibility for their own actions.




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          • #6
            Thx guys for the feedback.

            I should have been more clear in my original post -- not worried that the exhaust is too hot per se – I AM concerned that there is sufficient water cooling at the tip of the manifold so that the hose will be able to withstand it.

            Mentioned engine water temp only as indicator that the rest of the cooling circulating system seems to working just fine.

            Ski Bum, are you saying that the exhaust hose is supposed to be able to withstand 1200 degrees? I tried to look at some SAE specs but came up with much lower numbers (but must confess to not knowing much about it.

            Coming from two TBIs with regular manifolds and risers, this heat is whole new territory -- just trying to figure out if normal / safe to run?

            Thanks again.


            Oh, and mentioned the kink as it only appeared after running -- after it smelling like melted rubber and actually smoking a bit on the outside of the hose. The starboard side was very hot too, but still looks the same, without kink:

            Last edited by fbroen; 03-24-2008, 08:44 AM.

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            • #7
              I can say, it looks better w/o the kink!
              Charter Member Number 1

              Quote: 2RLAKE,
              At some point in time people need to wake up, remove their cranial intrusion into their own rectal areas, and take responsibility for their own actions.




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              • #8
                I have an 08 X-star MCX and it it likewise is warmer at the end of the CAT than my 05 X-2 MCX. I am told by an auto engineer that I know that many catalytic converters require temps near 1000F to work efficiently and that after looking at the Indmar/MC set up in my boat, he predicted that the temp coming out the CAT would be around 500F.
                2008 X star, 2005 X2

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                • #9
                  Yes that temp will melt the rubber hose. The 900 deg to 1200 deg is 2" out of the exhaust port. Water is injected after that to cool it down. I would fire it up on land with a flush kit. Make sure water is coming out the tail pipes. If not you have a problem and contact MC.

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                  • #10
                    Thx. Yeah, water is coming out of the tailpipes. Everything seems to circulate fine.

                    Just shocked about how hot the exhust hoses get on the CAT system -- but this does appear to be how it is all designed.

                    Big change from the traditional setup for sure.... Seems like manual should include something aliong the lines of, "Don't worry if you think the exhaust hoses will melt -- this is just the way it is now...."

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                    • #11
                      Side note - its interesting that the cats are so hot and right next to the air intake. Would be nice to see a fresh air source so that the intake air is not so hot. Would probably be a nice bump in HP with a cool intake charge vs. the hot air.
                      2005 ProStar 197TT, #28 of 100

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                      • #12
                        Originally posted by fbroen
                        Thx guys for the feedback.

                        I should have been more clear in my original post -- not worried that the exhaust is too hot per se – I AM concerned that there is sufficient water cooling at the tip of the manifold so that the hose will be able to withstand it.

                        Mentioned engine water temp only as indicator that the rest of the cooling circulating system seems to working just fine.

                        Ski Bum, are you saying that the exhaust hose is supposed to be able to withstand 1200 degrees? I tried to look at some SAE specs but came up with much lower numbers (but must confess to not knowing much about it.

                        Coming from two TBIs with regular manifolds and risers, this heat is whole new territory -- just trying to figure out if normal / safe to run?

                        Thanks again.


                        Oh, and mentioned the kink as it only appeared after running -- after it smelling like melted rubber and actually smoking a bit on the outside of the hose. The starboard side was very hot too, but still looks the same, without kink:


                        What you are smelling IS NOT the rubber hose. What you are smelling is the UNIQUE smell of engine paint getting hot and setting into the motor. It will last for the first 5-8 hours as the motor gets hot then cools. I had the MCX in my X-1 same set up. Ran for 100 + hours last year. You won't have any problems. That engine paint smell is normal. Always reminds me. THIS IS A NEW BOAT. Sort of like that NEW CAR SMELL that only last for about a month or so.

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                        • #13
                          JimBaws:

                          Note fbroen's later comment -
                          "Oh, and mentioned the kink as it only appeared after running -- after it smelling like melted rubber and actually smoking a bit on the outside of the hose. The starboard side was very hot too, but still looks the same, without kink:"

                          He observed smoke off the hose.

                          I have an '08 X2 (RTP 1) and may also have experienced this problem. Smell is not engine paint, but more of a burnt rubber smell. I will check it out next week when I fire up the boat after winter.
                          '08 X2 Switch Old School, RTP 1, Perfect Pass

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                          • #14
                            Hours 3-7 on the engine today. Smoke on outside of hose will develop any time running at 3000 rpm or above for a while. (See below by hose clamps)

                            Hoses are nice and cool about 6-8 inches below the top, so cooling defintively circulating. Looked at the tips under way today, and lots of water is gushing out.

                            Smoking hoses just part of the CAT setup...

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                            • #15
                              smoking of the hose does not seem normal...

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