A bad valve does give an inconstant back pressure sound that
reminds me of an old Crist Craft motor boat.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Will Honea wrote:
>
> Just wondering - wouldn't the old test of hanging a shop cloth over
> the end of the tailpipe pretty well identify a possible valve problem?
> Hold it so it hangs straight over the end of the pipe. It will blow
> out, maybe falling back to touch the pipe, unless you have an actual
> exhaust valve problem which will try and suck it up the pipe when that
> cylinder is in the right position. That will cause a backfire, BTW,
> and it can be pretty hard to spot if it's a weak valve spring.

 

A bad valve does give an inconstant back pressure sound that
reminds me of an old Crist Craft motor boat.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Will Honea wrote:
>
> Just wondering - wouldn't the old test of hanging a shop cloth over
> the end of the tailpipe pretty well identify a possible valve problem?
> Hold it so it hangs straight over the end of the pipe. It will blow
> out, maybe falling back to touch the pipe, unless you have an actual
> exhaust valve problem which will try and suck it up the pipe when that
> cylinder is in the right position. That will cause a backfire, BTW,
> and it can be pretty hard to spot if it's a weak valve spring.

 

A bad valve does give an inconstant back pressure sound that
reminds me of an old Crist Craft motor boat.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Will Honea wrote:
>
> Just wondering - wouldn't the old test of hanging a shop cloth over
> the end of the tailpipe pretty well identify a possible valve problem?
> Hold it so it hangs straight over the end of the pipe. It will blow
> out, maybe falling back to touch the pipe, unless you have an actual
> exhaust valve problem which will try and suck it up the pipe when that
> cylinder is in the right position. That will cause a backfire, BTW,
> and it can be pretty hard to spot if it's a weak valve spring.

 

A crack in the exhaust system will be less likely to be found after
the metals have expanded with heat. You don't need a stethoscope, you
could put your hear directly on the manifolds if you like.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"ezeppelin@msn.com" wrote:
>
> > Make yourself a stethoscope and see if you can find it cold.
>
> Not sure I follow. If by "cold" you mean with the engine not
> running... there wouldn't be any sound anywhere in the system... so
> I'm not sure how I would find the leak with a stethoscope?

 

A crack in the exhaust system will be less likely to be found after
the metals have expanded with heat. You don't need a stethoscope, you
could put your hear directly on the manifolds if you like.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"ezeppelin@msn.com" wrote:
>
> > Make yourself a stethoscope and see if you can find it cold.
>
> Not sure I follow. If by "cold" you mean with the engine not
> running... there wouldn't be any sound anywhere in the system... so
> I'm not sure how I would find the leak with a stethoscope?

 

A crack in the exhaust system will be less likely to be found after
the metals have expanded with heat. You don't need a stethoscope, you
could put your hear directly on the manifolds if you like.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"ezeppelin@msn.com" wrote:
>
> > Make yourself a stethoscope and see if you can find it cold.
>
> Not sure I follow. If by "cold" you mean with the engine not
> running... there wouldn't be any sound anywhere in the system... so
> I'm not sure how I would find the leak with a stethoscope?