That's pretty simple Lloyd,
Gas engines rev higher RPMs, and gasoline burns hotter then diesel. It
also has some unpleasent additives which affect metals. Just look at the
tailpipe of an old Buick.
--
Capt. Frank Hopkins

www.home.earthlink.net/~aartworks
"Lloyd Sumpter" wrote in message
...
On Sat, 31 Jan 2004 19:35:49 +0000, John H wrote:

On Sat, 31 Jan 2004 18:42:24 -0500, Wayne.B

wrote:

On Sat, 31 Jan 2004 14:59:02 -0500, John H
wrote:

How long can I go without replacing the exhaust manifolds and risers
on my
Mercruiser 5.7L?

====================================

Not as long as you'd like :-)



Well, I'm just replacing the riser on my Universal Diesel after about 10
years.
It's still good, but I'm replacing the engine, and the old one doesn't
fit
The manifold is also fine (just had it checked and de-rusted a few years
ago),
but it's being replaced along with the rest of the engine.

Donno why gas engines seem to go through manifolds and risers so much
faster
than diesels...

Lloyd Sumpter
"Far Cove" Catalina 36 - New Engine sitting on galley sole while
stringers are
being modified...