the exhaust. This problem could mean the end of your engine if
you don’t get it corrected right away. A breach such as this could
also dump water into one or more cylinders.
With the engine and its cooling system cold, remove the
header tank cap (where you add fresh water to your system), start
the engine, and check for bubbles rising from the water inside
the header tank. If there are bubbles, this could signify a blown
head gasket or a breach in the casting. Tiny bubbles at first, which
soon stop, are not what I’m talking about. The type of bubbles to
which I’m referring would continue and be significant. If you do
this, take great care not to burn yourself. As the water heats, it will
begin to overflow because it’s expanding.
Yes, you could have deposit buildup on the heat exchanger;
it happens over time, and the exchanger tubes should be periodically cleaned. But it’s unlikely this could cause all the symptoms
described.
Missing A Screw?
Can I use stainless-steel screws in place of bronze on an
impeller housing that has a few screws missing? Will the stainless
set up some sort of action with the bronze housing?
— Robert Gresko
Dundee, IL
John Adey: Your concern is valid: Can there be some type of
galvanic action between the two metals you’d like to use together?
Going back to high-school chemistry class, let’s look at the galvan-
ic series table. I’m concerned about the “anodic index” in volts.
Different metals have a different rating; take a look at this excerpt
from an online engineering handbook: www.engineersedge.com/
galvanic_capatabil-
ity.htm (misspelling of
compatibility is inten-
tional.)
Metal Type
Brass & Bronze
Stainless Steel
(Type 316)
Anodic Index (V)
0.40
0.50
Father Knows Best
Back in the mid-1990s, I bought a 4-hp Yamaha outboard. I
probably didn’t put more than five hours on it. I started it at least
once a year in a five-gallon bucket of fresh water just to make sure
it was able to run. Last year when I ran it, I noticed the water pump
witness stream, which comes out of the bottom of the engine
block, was not steady. The flow was sputtering. The water stream,
which mixes with the exhaust gases, always sputtered, as I would
expect. After about five minutes of running, I noticed small puffs of
steam intermixed with the sputtering water from the engine block,
