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  1. #1
    Vern's Avatar
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    Easy J pipe leak testing

    I found an easy way to check if your J pipe is leaking exhaust from the flex joint. A few symptoms are carbon on the J pipe, or on the motor or hull around the joint, and carbon in your SC inlet, etc. Also if you have your air intake inside the hull, your motor will not run optimally since it is pulling some exhaust in rather than fresh air. To test, pull your waterbox and J pipe, get a 2.75” leak tester $30 from http://www.siliconeintakes.com/index.php?cPath=8&osCsid=9f744cef08600842b247bd8e5 7b1d52b and clamp that tester over the waterbox exit; re-clamp the J pipe to the water box. Spray soapy water (I used Fantastic Clean & Shine – worked great) on the flex joint, then put some pressure into the tester. Plug the flex/flange joint opening with your hand, a ball, towel, anything, it does not take much … with mine, as soon as I put my hand over the opening, the flex immediately blew a bunch of foam … so I think my J pipe flex joint is shot. Another reason to not wait to get your exhaust manifold fixed by Friebe …

    I was curious though … SS flex joints are not terribly expensive and I wondered about cutting the welds on this one, and having a new one welded on … input? Has anybody tried this? Seems a shame to junk a $700 J pipe when it is only the flex joint that has failed … I also wondered if the flex joint is even needed? I was tempted to weld the inner and outer pipes together, eliminating the leak (and the flex). The exhaust is coupled twice with silicone, so it almost seems like the flex joint is overkill then … I would love to see a picture of the new 2008 exhaust setup … anybody post a good clear shot of that yet? Is the exhaust manifold the same?


  2. #2
    I have a Jpipe with a leaking flex joint and I was wondering the same thing about replacing just the flex joint. I am not qualified to do this myself so if anyone out there is I most likely will take advantage of your service. it's a shame that you have to junk such an expensive part because of the flex joint.......I would love to find an alternative,,,,,,I just bought a used J-pipe from jr rxp meanwhile........I hope he is a reputable seller

  3. #3
    Site Admin Green Hulk's Avatar
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    Jr RXP is a good guy.


    Good info Vern

  4. #4
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    Couple things wrong with your test, based on what I read...

    Did you plug the 3 pisser outlet holes on the bottom of the Jpipe before you pressurized the waterbox?

    If you didn't, you would get air traveling into the water jacket, thus creating foam if it is failing at the water jacket joint...which is thin based on the attached picture...


    The proper way to test the Jpipe is to attach the exit to an air source, like a vacuum cleaner in reverse or an air blower for pool toys...and not to incoude the 3 pisser holes...

    THEN spray soapy water on the flex and plug it with your hand, or even place it on a rubber mat....if it foams ,then the flex/weld areas have failed....if not, then the water jacket failed in your previous test.....
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  5. #5
    Vern's Avatar
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    Danny, good input ... I do not have the equipment or fittings to do the test I would LIKE to do, so this was the 'cheap and easy' route. I did not plug the 3 pissers since I believe my water-jacketing is fine, but I will block those and do the test again to verify that it is indeed the flex joint rather than the water jacket leaking. Based on all the evidence, I pretty much knew my flex joint was leaking exhaust (lots of dry carbon), but I had no indication of water-jacket leaks. But it would be smart to isolate and test both; I will do that ...

  6. #6
    Vern's Avatar
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    Update - this works

    I got a used J pipe from Jose (JR RXP) and tested this one the same way I tested my J pipe ... NO LEAKS, NO BUBBLES. I just wanted to let people know that my original test did work well, and is an extremely easy way to test. I tested both tonight when Dan (RXP'in MI) came over ... as soon as I plugged the J pipe inlet with my hand, my old J pipe started bubbling and foaming. The J pipe I bought from Jose did not bubble at all ... as I suspected, my J pipe was shot and the pipe I got from Jose was good (THANKS Jose!).
    Last edited by Vern; 01-21-2008 at 09:45 PM. Reason: oops

  7. #7
    Whats that whistling noise? jtskier11's Avatar
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    How does the early manifold compare to the 08 piece? Or are they the same minus the j-pipe?

  8. #8
    Moderator The Bandit's Avatar
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    Quote Originally Posted by Vern View Post
    I got a used J pipe from Jose (JR RXP) and tested this one the same way I tested my J pipe ... NO LEAKS, NO BUBBLES. I just wanted to let people know that my original test did work well, and is an extremely easy way to test. I tested both tonight when Dan (RXP'in MI) came over ... as soon as I plugged the J pipe inlet with my hand, my old J pipe started bubbling and foaming. The J pipe I bought from Jose did not bubble at all ... as I suspected, my J pipe was shot and the pipe I got from Jose was good (THANKS Jose!).
    Good deal Vern, I will be doing this on mine real soon. I have a new exhaust manifold coming to replace my melted one.

  9. #9
    Best of both worlds! RXP & RXT's Avatar
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    The way I test my j pipes is to take them off the ski turn them on end so the flexi faces upward and fill up the area between the inner pipe and the flexi with water. If the water goes down then its stuffed.

    Its a simple test that needs no tools to do once the j pipe is off.

    I took a broken j pipe in to the local exhaust shop but they said the flexi was too short to replace, cant buy them that small, so they just steretched the inner pipe and welded it up solid inside the flexi. I have run it for about 30 hours with no problems. Way cheeper than a new one.
    Got my 1000rpm back too!!

  10. #10
    Vern's Avatar
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    Great idea on the testing, that would be even easier ...

    I thought that you could just weld that thing up with no issues ... good to hear, thanks for the input!

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