Re: Exhaust

From: Barry Oliver (barrysuperhawk@comcast.net)
Date: Sat Apr 04 2009 - 23:02:11 EDT


jon@dakota-truck.net wrote:
> Phillip Batson <pbatson68@yahoo.com> wrote:
>
>
>
>>Just want to get your opinions on working on the exhaust system.
>>I've replaced the muffler to the end in the past, and that was
>>fairly easy. But this time, I have a leak up near the engine. Looks
>>like the driver side, where the exhaust connects to the header. It
>>is really rusted up where they are bolted together, and thats about
>>where I'm hearing it. I'm not sure how it connects underneath as I
>>haven't dropped the skid plate on it yet. I'm a little worried about
>>driving it like that as well, having all that hot exhaust dumping
>>right into the engine compartment.
>
>
>>How much of a p.i.t.a. would it be to work on? Am I going to have to
>>do both sides at once? Is it worth it to take it to somewhere like
>>meineke?
>
>
>
> I'm not 100% sure how the exhaust system is put together on the
> 4.7, so take this with a grain of salt, but in my experience, usually
> these types of problems are due to the clamps and hardware itself
> rusting out. The pipes themselves do rust, but they seem to be some
> sort of alloy that rusts much slower - might even be a low grade of
> stainless.
>
> Anyway, if the problem is right where the pipe attaches to the
> exhaust manifold, chances are good that the pipe itself is OK, but the
> clamp or one of the bolts has rusted through and broken. Usually the
> way this connection is made is for the end of the exhaust pipe to be
> flared, sort've like a brake line fitting, except its just a single
> flare, not a double flare. The end of the exhaust manifold has a
> matching shape, and fits inside the end of the pipe. There will be a
> flange on the exhaust pipe with a couple of holes in it, and the
> exhaust manifold will have a similar flange, some cast-in ears/holes
> or possibly even threaded holes which match the flange on the pipe. A
> pair of bolts are used to draw these two pieces together.
>
> Its pretty common for this flange to break or for one of the bolts
> to break, and this causes the pipe to be no longer held tightly
> against the exhaust manifold, hence the leak.
>
> The flange on the exhaust pipe is slipped into place by the
> manufacturer prior to flaring the end of the pipe, so if that is what
> has broken, obviously you can't just replace it with the same style
> flange. However, most auto parts stores carry a replacement which is
> a two piece flange, that you can slip together with the pipe in place.
> Check the exhaust section where they have the exhaust clamps, hangers,
> etc.
>
> The job isn't too hard, as long as you've got enough clearance.
> Depending on how bad things are, you may need to cut the old bolts
> off. Basically, you just put the new flange on there, and bolt it
> into place. It might not be a bad idea to use some stainless steel
> hardware to help prevent the problem in the future, or at least make
> dissasembly easier. A few coats of high temp exhaust paint on the
> replacement flange could help to extend its life.
>
> Anyway, that's just a guess on my part, obviously you'll need to
> stick your head in there and find out exactly what is wrong before
> you'll know what the job entails, but based on what you described,
> that's my guess as to the problem.
>
> The exhaust leak could throw off your O2 sensor readings and
> obviously is annoying to listen to, but shouldn't damage anything.
> Obviously, its something you'd want to address soon, but I wouldn't
> worry about driving the truck.
>
>

Oh, yeah, the stainless hardware is only a good idea if you double nut
with 2 lock washers. I had stainless bolts and I couldn't keep them
tight to save my life. Apparently the heat cycles were enough to loosen
  them.



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