I have 1957 a six cylinder Gray which is making a clanking noise at the
bottom of the second cylinder. I wonder what I might expect to be the
problem

When we pull the plug wire the noise dissipates. I get 750 compression on
all cylinders but this one is 550. I checked the lifters and springs which
appear to be fine. Not being familiar with motors I am unsure of what to
expect when I find a mechanic who can visit my boat. Can anyone give me
their best guess as to what would make a clunking sound or backfiring
sound..
--
Doug

Rod bearing?

D Milne wrote:

I have 1957 a six cylinder Gray which is making a clanking noise at the
bottom of the second cylinder. I wonder what I might expect to be the
problem

When we pull the plug wire the noise dissipates. I get 750 compression on
all cylinders but this one is 550. I checked the lifters and springs which
appear to be fine. Not being familiar with motors I am unsure of what to
expect when I find a mechanic who can visit my boat. Can anyone give me
their best guess as to what would make a clunking sound or backfiring
sound..
--
Doug

Bad wrist pin. Bearings do not get quiet like a wrist pin.
Bill

"Jim Kelly" wrote in message
...
Rod bearing?

D Milne wrote:

I have 1957 a six cylinder Gray which is making a clanking noise at the
bottom of the second cylinder. I wonder what I might expect to be the
problem

When we pull the plug wire the noise dissipates. I get 750 compression
on
all cylinders but this one is 550. I checked the lifters and springs
which
appear to be fine. Not being familiar with motors I am unsure of what to
expect when I find a mechanic who can visit my boat. Can anyone give me
their best guess as to what would make a clunking sound or backfiring
sound..
--
Doug

"Jim Kelly" wrote in message
...
I beg to differ. Failed main bearings will often quiet down when the
spark plug
is disconnected on the offending cylinder.

Main bearings? Perhaps you meant rod bearings?

"Calif Bill" wrote in message ...
Bad wrist pin. Bearings do not get quiet like a wrist pin.
Bill

Had that problem in a car once. Sounded like a diesel until it got
good and warm, then would quiet down quite a bit. But when you first
started it, it sound like a couple of hammers trying to beat their way
our of the block.

Got all the wrist pins replaced. Problem solved.



"Jim Kelly" wrote in message
...
Rod bearing?

D Milne wrote:

I have 1957 a six cylinder Gray which is making a clanking noise at the
bottom of the second cylinder. I wonder what I might expect to be the
problem

When we pull the plug wire the noise dissipates. I get 750 compression
on
all cylinders but this one is 550. I checked the lifters and springs
which
appear to be fine. Not being familiar with motors I am unsure of what to
expect when I find a mechanic who can visit my boat. Can anyone give me
their best guess as to what would make a clunking sound or backfiring
sound..
--
Doug