wrote in message
oups.com...
Thanks for replies.
Don't know about bad diode/ stator winding, Tim. Will take Alt to shop
to bench test.
Engine is Mercruiser MCM260. S/N is 6678458. Alt says Arco #60109
(marine SAE J1171)
Also says made by Mando on back. 55A.

At idle it was putting out 40A which Alternator shop guy said was
normal

I do have rust on main pulley, not on Alt tho. There's one culprit...

...couple questions from the Stupid ? Dept.
-- How do I find if I have 'bad engine ground'...?
-- How do I Iocate it and check to see if the fuse between battery and
alternator is good?

STB

The fuse is easy. Look for about a 1 in" square thing attached to the same
post on the starter that the + battery cable is attached to. Attached to the
square thing is a wire that goes to the alternator. The square thing is a
fuse. Check it with an ohmmeter.
The main engine ground is a stud on the back of one of the heads. There will
be a battery cable attached, and maybe some other grounds. To check engine
ground, set your voltmeter to 2 volt DC scale. Attach black lead to battery
negative. Attach red lead to a good bare metal spot on the engine block.
Read the meter while the engine is cranking over. Anything over .2 volts
means a bad connection somewhere.
Jim