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    Question about exhaust elbow...-gctid397200

    Just a real quick question about an exhaust elbow I recently purchased for my repower. This is the only aftermarket 90 degree exhaust mixing elbow available for the Perkins 4.108. The threaded female end connects to a flange mounted to the manifold and the smooth end connects to a rubber marine exhaust hose. The elbow is constructed of cast iron.Here is my dilemma: The smooth male end is 2 3/8 inches outer diameter and my rubber exhaust hose is 2 1/2 inches inner diameter. This gives me 1/8 inch wiggle space; and my exhaust hose is quite rigid and cannot be compressed enough with hose clamps to tightly fit around the 2 3/8 inch elbow. If I go any tighter, I will most likely end up breaking the hose clamp.I posted pics below.

    [img]/media/kunena/attachments/vb/700880=29402-Exhaust Elbow 1.jpg[/img]

    [img]/media/kunena/attachments/vb/700880=29401-Exhaust Elbow 2.jpg[/img]I am faced with two options. I can either cut the 2 3/8 inch piece off the exhaust mixing elbow and weld a 2 1/2 inch OD cast iron pipe onto the elbow or use something to build it up 1/8 inch. I thought about building it up with JB Weld, but I have concerns about it withstanding (on a long term basis) the vibration of my Diesel engine. Besides, my mechanic refuses to install an elbow built up with JB Weld.Does anyone have suggestions for increasing the outer diameter of the exhaust elbow by 1/8 inch?Thanks in advance...

    #2
    as they make the 2 3/8 diameter elbows there's very likely a 2 3/8 ID exhaust hose available.

    I agree with your mechanic about JB weld, I'd refuse to do that ugly fix too.

    Comment


      #3
      My entire exhaust system is 2 1/2 inch. This is the only component with the 2 3/8 inch fitting. It is more viable to address this fitting than the entire system.

      Comment


        #4
        Ditto.... NO J/B Weld!

        The clamps that may apply enough force to compress this hose, will be T-bolt style clamps.

        One T-bolt clamp can take the place of two standard worm screw band clamps if need be.



        Here's one with a radius to the T-bolt.



        Use a silicone spray underneath the band so that it can slip against the rubber while being tightened.

        I have seen where rubber sheet goods, or odd size thin wall hoses, were used as a shim affair.

        If you are shy by only 1/8", perhaps wrapping a 1/16" thick piece of good quality rubber strip around the cast iron outlet may bring the fit to within specs for your hose ID.

        Maybe glue this to the cast iron outlet to hold it in place while you're fitting the exhaust hose onto it.

        I'd still use the T-bolt style clamps.

        .

        Attached files [img]/media/kunena/attachments/vb/700924=29413-Exhaust outlet shim for Ed 2.jpg[/img] [img]/media/kunena/attachments/vb/700924=29411-Exhaust outlet shim for Ed.jpg[/img]
        Rick E. Gresham, Oregon
        2850 Bounty Sedan Flybridge model
        Twin 280 HP 5.7's w/ Closed Cooling
        Volvo Penta DuoProp Drives
        Kohler 4 CZ Gen Set

        Comment


          #5
          "The clamps that may apply enough force to compress this hose, will be T-bolt style clamps.

          One T-bolt clamp can take the place of two standard worm screw band clamps if need be."

          Really really good advice here as we have the T-clamps on all the exhaust elbows and they are night and day different from regular clamps.
          Northport NY

          Comment


            #6
            smitty477 wrote:
            ......... Really really good advice here as we have the T-clamps on all the exhaust elbows and they are night and day different from regular clamps.
            Yes, they sure are, and these also help solve the typical OEM Volvo Penta exhaust riser coupler (too short) issues.

            A single T-bolt clamp can be placed further up onto the riser..... away from the scalloped area.
            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #7
              If it were me I'd take it to a welder and have him build a lip up on the existing female; that way you'd have a ring to seal to. A competent tig welder ought to be able to weld onto the cast. He may even be able to weld a sleve on it to match you pipe id. I think clamping it down will leak eventually.

              Chay

              Comment


                #8
                Doesn't the factory made one fit?

                I am a COF and a retired engineer. I have found throughout life, that when you cut corners to save money, it winds up costing more in the longrun.

                However, what do I know?
                Captharv 2001 2452
                "When the draft of your boat exceeds the depth of water, you are aground"

                Comment


                  #9
                  cfoss wrote:
                  If it were me I'd take it to a welder and have him build a lip up on the existing female; that way you'd have a ring to seal to. A competent tig welder ought to be able to weld onto the cast. He may even be able to weld a sleve on it to match you pipe id. I think clamping it down will leak eventually.Chay
                  Cast iron can be TIG welded if it is properly pre-heated, and then properly cooled.

                  The trick would be getting an even bead around the perimeter, in which case things like this are rotated on a turn table while the TIG weld is being performed.

                  The rubber shim idea should work, and it should not allow the hose to slip out of position.

                  However, the "bead" would certainly be an added assurance!

                  It may not necessarily need to be full circumference either! Perhaps a short one at 12:00 O'clock, and one at 6:00 O'clock positions.

                  .
                  Rick E. Gresham, Oregon
                  2850 Bounty Sedan Flybridge model
                  Twin 280 HP 5.7's w/ Closed Cooling
                  Volvo Penta DuoProp Drives
                  Kohler 4 CZ Gen Set

                  Comment


                    #10
                    Thanks for all the responses. Ultimately, I decided to build up the fitting with some Seacast, which was left over from my rebuilding my transom. Just add water, slap it on the elbow, allow to dry, and the problem is solved! :kidding

                    captharv wrote:
                    Doesn't the factory made one fit?

                    I am a COF and a retired engineer. I have found throughout life, that when you cut corners to save money, it winds up costing more in the longrun.

                    However, what do I know?
                    If a such an elbow with a 2 1/2 inch fitting was available, I would have bought it in a heartbeat and this thread would have been entirely unnecessary. Saving money is not the imperative here. Establishing compatibility between two dissimilar sized fittings and doing so properly is my goal.

                    cfoss wrote:
                    If it were me I'd take it to a welder and have him build a lip up on the existing female; that way you'd have a ring to seal to. A competent tig welder ought to be able to weld onto the cast. He may even be able to weld a sleve on it to match you pipe id. I think clamping it down will leak eventually.

                    Chay
                    2850Bounty wrote:
                    Cast iron can be TIG welded if it is properly pre-heated, and then properly cooled.

                    The trick would be getting an even bead around the perimeter, in which case things like this are rotated on a turn table while the TIG weld is being performed.

                    The rubber shim idea should work, and it should not allow the hose to slip out of position.

                    However, the "bead" would certainly be an added assurance!

                    It may not necessarily need to be full circumference either! Perhaps a short one at 12:00 O'clock, and one at 6:00 O'clock positions.

                    .
                    I'm taking the elbow to A1 Welding and Fabrication this afternoon. They will be able to weld a bead around it and have quoted me a very reasonable price.

                    Comment


                      #11
                      I took the elbow to A1 Fabrication and Welding in Sacramento yesterday to get a bead welded around it. Being that it is made from cast iron, they heated it up slowly, applied the bead, and placed it back in the oven for more heat, and slowly cooled it off. The elbow survived the wrath of the arc welder and made it out alive. It's all pretty and blue, waiting to be connected to the manifold.

                      [img]/media/kunena/attachments/vb/701427=29445-Blue Exhust Elbow.jpg[/img]Now I'm waiting for the flange that allows me to connect this elbow to my manifold. Once it arrives (hopefully Monday or Tuesday), the project can continue.Thanks again to everyone for the help!

                      Comment


                        #12
                        Ed, I don't want to sound rude or disrepectful..... but I don't get this!

                        Why is this bead not out towards the end of the fitting as to ensure that the band clamp prevents hose slippage?

                        Isn't this a reason that your mechanic did not like the rubber shim idea?

                        And why Arc welded instead of TIG welded?

                        Attached files [img]/media/kunena/attachments/vb/701464=29446-Exhaust outlet shim for Ed 3.jpg[/img]
                        Rick E. Gresham, Oregon
                        2850 Bounty Sedan Flybridge model
                        Twin 280 HP 5.7's w/ Closed Cooling
                        Volvo Penta DuoProp Drives
                        Kohler 4 CZ Gen Set

                        Comment


                          #13
                          Im with rick on this one. Unless im not understanding the bead should be on the opening so that the hose wont slip off when clamped.

                          Also i think what I would do isinstall the hose on the elbow fill the gap with high temp rvt making sure a good fill all the way aroundwith as much fill as possible with out flowing excess on the inside.

                          Let it set up hard then clamp it.

                          Juat a thought.

                          I might be inclined to move that bead.
                          1989 Avanti 3450 Sunbridge
                          twin 454's
                          MV Mar-Y-Sol
                          1979 Bayliner Conquest 3150 hardtop ocean express.
                          Twin chevy 350's inboard
                          Ben- Jamin
                          spokane Washington

                          Comment


                            #14
                            I have a bronze exhaust elbow installed on my Kohler 4 CZ that is beaded. The beads are both towards the outlet ends.

                            I guess what I'm saying Ed, is that I don't understand why the bead would have been placed at the inboard side of the outlet, rather than the extreme outlet side where the bead would prevent hose slippage.

                            If the intent behind the bead was to better seal the hose to the elbow...., then the bead would have been in the center, and then clamped near the top of it... or perhaps both sides of it.

                            Here are a few random examples.









                            This one apparently allows for either a hose connection, or a TP fitting connection.


                            Rick E. Gresham, Oregon
                            2850 Bounty Sedan Flybridge model
                            Twin 280 HP 5.7's w/ Closed Cooling
                            Volvo Penta DuoProp Drives
                            Kohler 4 CZ Gen Set

                            Comment


                              #15
                              How about that stuff used on motorcycle exhaust joints? Im not sure what it is called, but it is grayish, wraps around the exhaust pipe, and then the muffler or rest of the exhaust slips over it and clamps down on it. Maybe its not waterproof?

                              Comment

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