Sounds like an Exhaust leak

S

stephen thomas

New member
May 29, 2014
29
0
0
Hello,

So, I thought I had a bad exhaust manifold gasket and that the resulting
exhaust leak was making a lot of noise. Sure enough, the gasket had
disintegrated to almost nothing, so I replaced it this morning with a
Remflex, but when I started the engine, quickly realized that the bad
manifold gasket was not what had been causing the noise.

With the plastic fenders off, the engine hatch off, and the engine running,
I searched for the source of the noise. The noise is loudest from above. It
sounds like it's coming from inside the valve cover on the right side. As
far as I can tell, there is no exhaust leaking into the engine compartment,
but I swear it sounds just like blown out muffler.

I also noticed that the plastic electrical conduit that runs along the top
of the valve cover had been resting on it and was completely melted. I
didn't think the valve cover should be getting hot enough to do that.

If it wasn't so loud, I wouldn't think anything was wrong. It starts right
up, doesn't smoke and seems to have all it's power. Any idea what might be
happening here?

Thanks,
Steve T.
78 Eleganza
Santa Cruz, CA
 
Steve,
It is coming from the choke heat tube flange.
Put your fingers around it with the engine running.
Call me and I'll advise you.

On Sat, Oct 29, 2016 at 2:03 PM, Stephen Thomas
wrote:

> Hello,
>
> So, I thought I had a bad exhaust manifold gasket and that the resulting
> exhaust leak was making a lot of noise. Sure enough, the gasket had
> disintegrated to almost nothing, so I replaced it this morning with a
> Remflex, but when I started the engine, quickly realized that the bad
> manifold gasket was not what had been causing the noise.
>
> With the plastic fenders off, the engine hatch off, and the engine running,
> I searched for the source of the noise. The noise is loudest from above. It
> sounds like it's coming from inside the valve cover on the right side. As
> far as I can tell, there is no exhaust leaking into the engine compartment,
> but I swear it sounds just like blown out muffler.
>
> I also noticed that the plastic electrical conduit that runs along the top
> of the valve cover had been resting on it and was completely melted. I
> didn't think the valve cover should be getting hot enough to do that.
>
> If it wasn't so loud, I wouldn't think anything was wrong. It starts right
> up, doesn't smoke and seems to have all it's power. Any idea what might be
> happening here?
>
> Thanks,
> Steve T.
> 78 Eleganza
> Santa Cruz, CA
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Wow Jim, I think you nailed it!

I have an electric choke, so there's a cover over that hole. The cover is
badly warped and the gasket was completely gone except under the screws. It
looks like the melted part of the conduit is right where the exhaust was
blowing.

What a relief! I feared something much worse was wrong.

I'll give you a call on Monday to see about getting another.

Thanks!

Steve T.
78 Eleganza
Santa Cruz, Ca

> Steve,
> It is coming from the choke heat tube flange.
> Put your fingers around it with the engine running.
> Call me and I'll advise you.
>
> On Sat, Oct 29, 2016 at 2:03 PM, Stephen Thomas

>
> > Hello,
> >
> > So, I thought I had a bad exhaust manifold gasket and that the resulting
> > exhaust leak was making a lot of noise. Sure enough, the gasket had
> > disintegrated to almost nothing, so I replaced it this morning with a
> > Remflex, but when I started the engine, quickly realized that the bad
> > manifold gasket was not what had been causing the noise.
> >
> > With the plastic fenders off, the engine hatch off, and the engine
> running,
> > I searched for the source of the noise. The noise is loudest from above.
> It
> > sounds like it's coming from inside the valve cover on the right side. As
> > far as I can tell, there is no exhaust leaking into the engine
> compartment,
> > but I swear it sounds just like blown out muffler.
> >
> > I also noticed that the plastic electrical conduit that runs along the
> top
> > of the valve cover had been resting on it and was completely melted. I
> > didn't think the valve cover should be getting hot enough to do that.
> >
> > If it wasn't so loud, I wouldn't think anything was wrong. It starts
> right
> > up, doesn't smoke and seems to have all it's power. Any idea what might
> be
> > happening here?
> >
> > Thanks,
> > Steve T.
> > 78 Eleganza
> > Santa Cruz, CA
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
We can do it today

On Sat, Oct 29, 2016 at 3:01 PM, Stephen Thomas
wrote:

> Wow Jim, I think you nailed it!
>
> I have an electric choke, so there's a cover over that hole. The cover is
> badly warped and the gasket was completely gone except under the screws. It
> looks like the melted part of the conduit is right where the exhaust was
> blowing.
>
> What a relief! I feared something much worse was wrong.
>
> I'll give you a call on Monday to see about getting another.
>
> Thanks!
>
> Steve T.
> 78 Eleganza
> Santa Cruz, Ca
>
> On Sat, Oct 29, 2016 at 2:25 PM, Jim Kanomata

>
> > Steve,
> > It is coming from the choke heat tube flange.
> > Put your fingers around it with the engine running.
> > Call me and I'll advise you.
> >
> > On Sat, Oct 29, 2016 at 2:03 PM, Stephen Thomas

> >
> > > Hello,
> > >
> > > So, I thought I had a bad exhaust manifold gasket and that the
> resulting
> > > exhaust leak was making a lot of noise. Sure enough, the gasket had
> > > disintegrated to almost nothing, so I replaced it this morning with a
> > > Remflex, but when I started the engine, quickly realized that the bad
> > > manifold gasket was not what had been causing the noise.
> > >
> > > With the plastic fenders off, the engine hatch off, and the engine
> > running,
> > > I searched for the source of the noise. The noise is loudest from
> above.
> > It
> > > sounds like it's coming from inside the valve cover on the right side.
> As
> > > far as I can tell, there is no exhaust leaking into the engine
> > compartment,
> > > but I swear it sounds just like blown out muffler.
> > >
> > > I also noticed that the plastic electrical conduit that runs along the
> > top
> > > of the valve cover had been resting on it and was completely melted. I
> > > didn't think the valve cover should be getting hot enough to do that.
> > >
> > > If it wasn't so loud, I wouldn't think anything was wrong. It starts
> > right
> > > up, doesn't smoke and seems to have all it's power. Any idea what might
> > be
> > > happening here?
> > >
> > > Thanks,
> > > Steve T.
> > > 78 Eleganza
> > > Santa Cruz, CA
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> >
> >
> >
> > --
> > Jim Kanomata
> > Applied/GMC, Fremont,CA
> > jimk
> > http://www.appliedgmc.com
> > 1-800-752-7502
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Jim, you are simply amazing!

----- Original Message -----
From: "Jim Kanomata"
To: gmclist
Sent: Saturday, October 29, 2016 6:19:24 PM
Subject: Re: [GMCnet] Sounds like an Exhaust leak

We can do it today

On Sat, Oct 29, 2016 at 3:01 PM, Stephen Thomas
wrote:

> Wow Jim, I think you nailed it!
>
> I have an electric choke, so there's a cover over that hole. The cover is
> badly warped and the gasket was completely gone except under the screws. It
> looks like the melted part of the conduit is right where the exhaust was
> blowing.
>
> What a relief! I feared something much worse was wrong.
>
> I'll give you a call on Monday to see about getting another.
>
> Thanks!
>
> Steve T.
> 78 Eleganza
> Santa Cruz, Ca
>
> On Sat, Oct 29, 2016 at 2:25 PM, Jim Kanomata

>
> > Steve,
> > It is coming from the choke heat tube flange.
> > Put your fingers around it with the engine running.
> > Call me and I'll advise you.
> >
> > On Sat, Oct 29, 2016 at 2:03 PM, Stephen Thomas

> >
> > > Hello,
> > >
> > > So, I thought I had a bad exhaust manifold gasket and that the
> resulting
> > > exhaust leak was making a lot of noise. Sure enough, the gasket had
> > > disintegrated to almost nothing, so I replaced it this morning with a
> > > Remflex, but when I started the engine, quickly realized that the bad
> > > manifold gasket was not what had been causing the noise.
> > >
> > > With the plastic fenders off, the engine hatch off, and the engine
> > running,
> > > I searched for the source of the noise. The noise is loudest from
> above.
> > It
> > > sounds like it's coming from inside the valve cover on the right side.
> As
> > > far as I can tell, there is no exhaust leaking into the engine
> > compartment,
> > > but I swear it sounds just like blown out muffler.
> > >
> > > I also noticed that the plastic electrical conduit that runs along the
> > top
> > > of the valve cover had been resting on it and was completely melted. I
> > > didn't think the valve cover should be getting hot enough to do that.
> > >
> > > If it wasn't so loud, I wouldn't think anything was wrong. It starts
> > right
> > > up, doesn't smoke and seems to have all it's power. Any idea what might
> > be
> > > happening here?
> > >
> > > Thanks,
> > > Steve T.
> > > 78 Eleganza
> > > Santa Cruz, CA
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> >
> >
> >
> > --
> > Jim Kanomata
> > Applied/GMC, Fremont,CA
> > jimk
> > http://www.appliedgmc.com
> > 1-800-752-7502
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Jeeze Ken, what a mess. I was lucky, especially considering how much
mileage I put on it after I noticed the noise...wont do that again. I just
need to replace the conduit and the choke wire.

I think I'll get back into the habit of checking under the hatch every few
hours of driving.

Thanks,
Steve

> If the cover is warped, get both the gasket and a new cover. Jim has them
> both.
>
> That blown gasket is what ignited my engine 9 years ago.
>
> http://www.gmcmhphotos.com/photos/engine-fire/p17604.html
>
>
>
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
That was the ignitions source. It was not the fuel source. The fuel source was the carb in front of it.

I learned a lot from fighting that fire and saving the coach plus my house with attached garage. That is why I occasionally get on my soap box about
fire extinguisher types and fighting a vehicle fire.

I also once had a Ford once that I was working on catch fire from a fuel pump leak. It was in a garage that I was working for at the time and the
fire extinguishers were empty. I pushed it outside and got the fire out without burning it and the business to a crisp.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Hello Ken,
Which type of extinguisher do you recommend and any other details?
Thanks,
Mike
 
Since the majority of motorhome fires involve Gasoline, diesel, or propane, I suggest using AFFF or better yet AR-AFFF foam fire extinguishers.

The one draw back of AFFF is it will freeze at different temperatures depending on the type of AR-AFFF or AFFF used. Some freeze at 32F, others
freeze at 14F, and some freeze at temps well below 0 F.

After AFFF the next best would be CO2, and finally dry powder. I do not recommend Halon (or its substitutes) except in enclosed areas like the
propane refrigerator cabinet.

Dry powder makes a mess and in most cases is very caustic. (some are just baking soda) I used two of them and one halon on my engine fire and they
did not put my engine fire out.

I now carry two 2 or 3 liter AR-AFFF plus one CO2 extinguishers inside the coach. I keep one AR-AFFF inside the propane cabinet so it can be accessed
from outside the coach. I also have a couple of small cheap throw away AFFF ones around inside for kitchen type fires fires. They would also work on
engine or Onan fires.

I also have an automatic deployment halon one in my propane refrigerator compartment.

I would love to have an automatic deployment foam one in the engine area and the Onan area, but I have not found anyone making one that will not
freeze. I do not want to be removing a permanent mounted one every winter. Ken Henderson made a manual remote controlled one for his engine out of a
Kidde foam extinguisher about 8 or 9 years ago.

One of the board members of our local Airport board owns a fire protection products company. They make products primarily for large fire departments.
Their main products are fire hose nozzles and fire monitoring equipment. I have been trying to get them to make what I want in auto-deploy freeze
resistant foam for vehicles. They do make foam nozzles for fire trucks. This company is a 24x7 manufacturing facility. Making this is really too
small for them to do. All of the components to assemble these are readily available. It is just getting someone to assemble, charge, and market
them. The market is very small.

If you want some very small throw away foam ones to start with, start with these.

http://www.ebay.com/itm/Fire-Gone-2NBFG2704-White-Red-Fire-Extinguisher-16-oz-Pack-of-2-New/251884909182?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D40146%26meid%3Da5190586104b4bdd9ffba7f377d26f27%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D272373211748

They are made by a company in Florida. They private label them under several names. I have at least 3 different brands of them around the house and
in my cars. All were make by the same Florida company. These will freeze at 32F or lower.

I would suggest that you really need something larger than these in a GMC, but go with foam if possible.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
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