DS: sealing flexi tube exhaust joint
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  1. #1
    Fellow Frogger!
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    Default DS: sealing flexi tube exhaust joint

    Does anyone have a good solution for sealing the joint where the cast manifold pipe and the 'front' end of the flexi pipe meet?

    I have a nearly new flexi pipe and the original (1974) manifold pipe. The surface of the cast pipe is a bit rough; also, the flexi pipe (proper one for the D) is a fairly loose fit - nothing like the perfect fit at the other end, where the flexi pipe attaches to the muffler. The flexi pipe doesn't have any slots (to allow crimping with an exhaust clamp), but that's easily remedied with an angle grinder.

    Compounding the issue; whilst I have a new support clamp (the one that bolts onto the sump), it lacks the ability to compress the flexi pipe.

    I could cut slots in the 'front' part of the flexi pipe and fit a normal exhaust clamp forward of the factory support clamp, but it will still need a decent sealant of some sort to stop exhaust gas leakage. High temperature copper RTV silastic seems to be a common generic recommendation. If anyone has a view on this, or a better idea, I'd be pleased to hear about it.

    My attempts to seal this joint have so far been unsuccessful.

    Chris

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  2. #2
    Fellow Frogger
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    A new flex pipe has slots at one end only and this goes onto the downpipe. I think you may have better luck if you turn the flex pipe around. So, the flex pipe goes on the outside at the front. Make sure you do the small 8mm headed bolt on the bracket up before trying to fit the support clamp.

  3. #3
    Real cars have hydraulics DoubleChevron's Avatar
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    I'd pull the flex pipe off and take it into the local exhaust place. They'll make you one up with stainless braid for less than $100 that will then last the life of the car (CX's are stainless braid, and I've never heard of anyone ever needing to replace one).

    It should seal up no problems if you have slots cut on the flexi-exhaust. Is the flexible exhaust part you have now .... well flexable ?? If it's not it's probably coming loose at the joint due to engine movement. If you solve the problem I reckon the flexi-exhaust would break soon after.

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  4. #4
    Fellow Frogger!
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    Thanks, David and Shane.

    Shane, my flexi pipe is in perfect condition - no problem on that count.

    David, are you saying that the plain end of the flexi pipe should fit INSIDE the muffler inlet?

    If that's so, I think I'll be worse off with the slotted end of the flexi pipe over the downpipe, because the slotted end fits perfectly OVER the muffler inlet.

    Chris

  5. #5
    1000+ Posts daffyduck's Avatar
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    The pipe fits OVER the exhaust manifold down pipe.
    Remove the flex pipe.
    Clean off the tip of the outlet on the exhaust manifold with a wire brush, sandpaper, etc. Smear some JB weld around it and smooth it with a wet finger to rebuild the shape and make it smooth again if you have to..
    Find some muffler sealant at the parts house. It comes in a tube like toothpaste. It comes out soft and you can manage it with a wet finger as well.
    Put the whole thing back together with the sealant and clamp it down, and let it cure. It should be fine after that.

  6. #6
    Fellow Frogger
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    Yes, the slotted end of the flex pipe fits over the end of the downpipe, which is not slotted. Get that end right and then modify the muffler pipe or the other end of the flex pipe instead. I had a fight with these parts just before Christmas, so I can understand your frustration.

  7. #7
    Fellow Frogger!
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    Default DS exhaust

    Thanks, daffyduck and David.

    It's not the easiest spot to work, but I'll tackle it with renewed enthusiasm - and the benefit of your suggestions - when I next get some spare time.

    Chris

  8. #8
    Fellow Frogger
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    Chris, I found I had to cut about 1cm off the longer end of the bracket/clamp for the downpipe end as it interfered with the 8mm bolt head and wouldn't sit against the bracket on the engine properly. Not so easy lying on your back, no.

  9. #9
    Fellow Frogger!
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    Default exhaust bracket

    David,

    I've had no problem with the exhaust support bracket - apart from getting the 8mm bolt started once aligned with the bracket attached to the sump. Not much room in there.

    As you gather, my issue is more one of pipe diameter - and in the case of the downpipe, surface finish.

    Chris

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