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Thread: Exhaust Leak. Am I missing something?

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    Question Exhaust Leak. Am I missing something?

    As a few of you might know from my other thread (see Matt's cylinder head rebuild in the 7MGE forum) I rebuilt the head on my 7MGE back in February. Once I got the valve shims done everything was running and sounding great (actually it was too quiet, but a new, sportier exhaust will have to wait). However, about 2 weeks ago I developed what sounded like an exhaust leak. It seemed like it was coming from where the exhaust manifold connects to the downpipe. I checked, and sure enough the nuts were very loose even though I know they had been tightened down when I did the head rebuild AND new gaskets were used at this spot. So I tightened them up, but the exhaust leak sound was still there. After looking at the TSRM I noticed that the nuts were not supposed to be reused; so I ordered and fit new ones (making sure they were good and tight). The noisy exhaust remained. To make sure it was coming from this spot I blew air through the tailpipe and sprayed soapy water around this area. Sure enough bubbles formed exactly at this spot.

    My question is why did it take a month or so for the nuts to come loose? More importantly why didn't tightening the nuts up (especially with the new ones) fix the leak? Is it one of those things where you only get one shot at squishing the gasket and if it comes apart even a little you have to start over with a new gasket? Or, do you think it was because I used the gaskets from the non-Toyota engine gasket kit and maybe they just didn't fit right? Or is there something else I am missing completely in terms of correctly installing the gaskets in the 1st place? That last question is very important as I have ordered new Toyota gaskets and even new studs to go with the new nuts I mentioned previously. Your thoughts are appreciated as I hope to work on it tomorrow.

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    Default Re: Exhaust Leak. Am I missing something?

    Quote Originally Posted by slowerisfaster View Post
    As a few of you might know from my other thread (see Matt's cylinder head rebuild in the 7MGE forum) I rebuilt the head on my 7MGE back in February. Once I got the valve shims done everything was running and sounding great (actually it was too quiet, but a new, sportier exhaust will have to wait). However, about 2 weeks ago I developed what sounded like an exhaust leak. It seemed like it was coming from where the exhaust manifold connects to the downpipe. I checked, and sure enough the nuts were very loose even though I know they had been tightened down when I did the head rebuild AND new gaskets were used at this spot. So I tightened them up, but the exhaust leak sound was still there. After looking at the TSRM I noticed that the nuts were not supposed to be reused; so I ordered and fit new ones (making sure they were good and tight). The noisy exhaust remained. To make sure it was coming from this spot I blew air through the tailpipe and sprayed soapy water around this area. Sure enough bubbles formed exactly at this spot.

    My question is why did it take a month or so for the nuts to come loose? More importantly why didn't tightening the nuts up (especially with the new ones) fix the leak? Is it one of those things where you only get one shot at squishing the gasket and if it comes apart even a little you have to start over with a new gasket? Or, do you think it was because I used the gaskets from the non-Toyota engine gasket kit and maybe they just didn't fit right? Or is there something else I am missing completely in terms of correctly installing the gaskets in the 1st place? That last question is very important as I have ordered new Toyota gaskets and even new studs to go with the new nuts I mentioned previously. Your thoughts are appreciated as I hope to work on it tomorrow.
    Maybe need get correct gasket first to rule out is the gasket.

    Sent from my LG-H918 using Tapatalk

  3. #3
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    Default Re: Exhaust Leak. Am I missing something?

    Flanges might be bent or warped too. You could get a shop to look at it if a gasket doesn't work.

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    Default Re: Exhaust Leak. Am I missing something?

    Finally had a chance to work on the problem. I replaced the downpipe gaskets and the O2 sensor gasket. Unfortunately it still sounded like s#*t, but I couldn't figure out where the exhaust leak was coming from. So I swallowed my pride and brought the car into our service shop at work (I work at a Honda dealership). They used their smoke generator and discovered that the leak is coming from the EGR cooler. That really sucks because you all know how hard that is to get off with the head installed; but I think I can manage. Yet another lesson learned I suppose. I used the cheapo paper gasket from the top end gasket kit when I did the rebuild and apparently it has failed already. I have already ordered the Toyota metal gasket and will get to it sometime next week. At least it wasn't anything major and the gasket is relatively inexpensive. I'll report back when its back together.

    Now if only I can sell enough cars this month so I can fix the A/C next month...Anybody wanna buy a Honda? LOL!

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    Default Re: Exhaust Leak. Am I missing something?

    Got a chance to install the new EGR cooler gasket today. I'm so glad it sounds normal again. The exhaust leak was really embarrassing. Here is what the old one looked like. To quote Mythbusters "Well there's your problem right there".



    I really hope the OEM gasket doesn't give me any trouble. I wouldn't wish the job of changing that gasket on my worst enemy.

    Sent from my SAMSUNG-SM-G900A using Tapatalk

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    Default Re: Exhaust Leak. Am I missing something?

    Hah, after reading your post. I've fixed mine as well! Should put some loctite so you don't have to run into this issue again.
    Last edited by Nubus; May 26th, 2017 at 07:20 PM. Reason: Conditions changed.

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