rattling noise at low RPM

[Yousuf Khan]

I hear a metallic rattling noise at low RPM's, on my Tribeca (3.6L H6).
Only happens at low speed and low RPM, and it goes away after getting
upto speed. I am thinking that this is the heat shield around the
catalytic converter. I'm wondering what the usual dealer fix for a heat
shield is? Do they normally try to repair the heat shield, or do they
try to replace it with a new one? If they try to repair it, then how do
they repair it, by bolting it back in place, or welding it or what?

Yousuf Khan

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me thinks before you discover answers to the numerous questions you
have
there is an option of applying exhaust tape from a nearby autostore
between the exhaust pipe and the heatshield to kill some of that
and save some $$$.

here's one example, nevermind the moto application
http://www.youtube.com/watch?v=gqwbyvaN9d8

[cl...@snyder.on.ca]

yes, yes, and yes. Usually repair - usually by welding or clamping

[Davoud]

Yousuf Khan:

In some jurisdictions it is illegal to weld exhaust systems. Clamps and
bolts are required, because welds are prone fail under the vibration
that the exhaust system experience.

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm

[cl...@snyder.on.ca]

On Tue, 11 Jun 2013 10:13:12 -0400, Davoud <st...@sky.net> wrote:

>Yousuf Khan:
>
>> I hear a metallic rattling noise at low RPM's, on my Tribeca (3.6L H6).
>> Only happens at low speed and low RPM, and it goes away after getting
>> upto speed. I am thinking that this is the heat shield around the
>> catalytic converter. I'm wondering what the usual dealer fix for a heat
>> shield is? Do they normally try to repair the heat shield, or do they
>> try to replace it with a new one? If they try to repair it, then how do
>> they repair it, by bolting it back in place, or welding it or what?
>
>In some jurisdictions it is illegal to weld exhaust systems. Clamps and
>bolts are required, because welds are prone fail under the vibration
>that the exhaust system experience.

Name one. They are ALL welded from the factory. And welding the heat
sheild is NOT welding the exhaust anyway.(technically).

I've had more clamps let go (on stainless steel systems) than welds
over the last 15 years. The clamps rot off unless you use high quality
(read expensive) stainless steel clamps.

[AD]

On Jun 11, 6:43 pm, cl...@snyder.on.ca wrote:

I'm curious, do you use any loctite (blue or red) on clamp bolts
or it disintegrates at the exhaust temperatures so there's no point?

[Yousuf Khan]

On 11/06/2013 10:13 AM, Davoud wrote:
> Yousuf Khan:
>
>> I hear a metallic rattling noise at low RPM's, on my Tribeca (3.6L H6).
>> Only happens at low speed and low RPM, and it goes away after getting
>> upto speed. I am thinking that this is the heat shield around the
>> catalytic converter. I'm wondering what the usual dealer fix for a heat
>> shield is? Do they normally try to repair the heat shield, or do they
>> try to replace it with a new one? If they try to repair it, then how do
>> they repair it, by bolting it back in place, or welding it or what?
>
> In some jurisdictions it is illegal to weld exhaust systems. Clamps and
> bolts are required, because welds are prone fail under the vibration
> that the exhaust system experience.

They actually ended up removing the right-side heat shield! There is
apparently two catalytic converters and only the right-side heat shield
was loose, so they took it off. Is this okay?

Yousuf Khan

[Geoff Welsh]

no, they should have clamped it
GW

[Davoud]

Davoud:

> > In some jurisdictions it is illegal to weld exhaust systems. Clamps and
> > bolts are required, because welds are prone fail under the vibration
> > that the exhaust system experience.

Yousuf Khan:

> They actually ended up removing the right-side heat shield! There is
> apparently two catalytic converters and only the right-side heat shield
> was loose, so they took it off. Is this okay?

It's OK by me, but I don't know what the law says in your jurisdiction,
or if there is a federal law.

It's worth remembering that the earliest catalytic converters did not
have heat shields. Then there were a few cases in which people parked
their cars in high, dry grass and the enormous heat set the grass
afire, burning the vehicle and, in some cases, spreading to become more
damaging fires. So watch where you park.

[Tim Conway]

"Yousuf Khan" <bbb...@spammenot.yahoo.com> wrote in message
news:51b6afb6$1...@news.bnb-lp.com...

I've had a number of Subies over the years since 1989, one of them, I don't
remember which one, rattled and needed the heat shield rrepaired. The
dealer said they welded it. It seems to be a common occurrence and practice
to weld them. They are not part of the exhaust, but part of the chassis
surrounding the exhaust.

[cl...@snyder.on.ca]

No it is not. They are there for a reason. Don't park in long dry
grass or you may find out firsthand ONE of the reasons.

[cl...@snyder.on.ca]

On Wed, 12 Jun 2013 21:13:11 -0400, Davoud <st...@sky.net> wrote:

>Davoud:
>> > In some jurisdictions it is illegal to weld exhaust systems. Clamps and
>> > bolts are required, because welds are prone fail under the vibration
>> > that the exhaust system experience.
>
>Yousuf Khan:
>> They actually ended up removing the right-side heat shield! There is
>> apparently two catalytic converters and only the right-side heat shield
>> was loose, so they took it off. Is this okay?
>
>It's OK by me, but I don't know what the law says in your jurisdiction,
>or if there is a federal law.
>
>It's worth remembering that the earliest catalytic converters did not
>have heat shields. Then there were a few cases in which people parked
>their cars in high, dry grass and the enormous heat set the grass
>afire, burning the vehicle and, in some cases, spreading to become more
>damaging fires. So watch where you park.

Definitely no federal law about welding exhaust parts if that's what
you mean - and the law states no emission control device may be
modified - so if it is fastened to the converter and not the floor you
COULD take that to mean the heat sheild cannot be removed, if you
stretch things a wee bit.

They are a SAFETY item, basically.

[cl...@snyder.on.ca]

Loc-tite lets go at the high end of exhaut temps - I never use it on
exhaust clamps - they tend to become self locking in a few weeks
anyway - <BG>. Stover nuts work better than lock washers if you do
need to lock the clamp. Or just hit them with the welder when you get
them tight.

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I have to assume no reason to lubricate the threads in this
application
to allow for lower wear and tear when the clamps rot and you are
reusing a stover? or there is some lubricant that can withstand
exhaust temps
for a few years

>  Or just hit them with the welder when you get
> them tight.

Ok, kinda makes sense to use a new bolt with a new stover nut on a new
application.
esp if you have spent the money on a better ($$$) clamp in the first
place

Any situations you can think of when you want to drill through and
safety wire the thing
together?

[cl...@snyder.on.ca]

The stover will be unuseable by the time the clamp rots off no matter
what you put on it. If you use stainless clamps it is a good idea to
lubricate the threads for assembly so they don't gall and seize while
you are tightening them in the first place.

>
>>  Or just hit them with the welder when you get
>> them tight.
>
>Ok, kinda makes sense to use a new bolt with a new stover nut on a new
>application.
>esp if you have spent the money on a better ($$$) clamp in the first
>place
>
>Any situations you can think of when you want to drill through and
>safety wire the thing
>together?

Mabee on an airplane.

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[snip]

> >They actually ended up removing the right-side heat shield! There is
> >apparently two catalytic converters and only the right-side heat shield
> >was loose, so they took it off. Is this okay?
>

[gasp]
I can't believe something like that happened in (litigious?) canada.