[Public-list] M3-20B Glow plugs glow now, but Š .

[Randy Katz]

George-- I sent a couple of photos for possible inclusion with this... Have
you seen them?  
 
Re:  Testing of old preheat solenoid and replacement with the new on a
M3-20B Universal diesel
 
         I performed various voltmeter tests on the old solenoid, as per
email from Mark Mpete53 at aol.com.  While not exactly following his expected
outcomes, the tests seemed to generally indicate a fault with the solenoid,
not with other wiring.
 
         I replaced the preheat solenoid. There were some positive outcomes:
         *  The engine warning buzzer turned off as soon as the glow plug
switch was depressed.  This hasn't happened since a couple of years ago when
it began remaining on until the start button was depressed.  (I never did
learn why.)
         *  The fuel pump could be heard to click rapidly with the
depressing of glow plug switch.  I dimly remember this happening sometime
soon after buying the boat, but not again in the years since, even after a
replacement (electric) fuel pump was installed two years ago.
         *  The engine started immediately after 15 sec. of glow plug-- as
was normal before this no-start stuff began a couple weeks ago.  Problem
solved, butŠ.
 
         Š A new problem showed itself with the new solenoid:  all the time
the engine is running, it drops about 200 rpms every 9 seconds or so for a
period of 2-3 seconds.  With the engine running and the power switch at
BOTH, the #1 (starting) batt. drops from 14.3 v. to 13.9 v. (as measured
directly off the batt and at the panel voltmeter)   The #2 house batt. drops
from 14.3 v to 13. 8v.  Throttled at a moderate idle it sounds at first as
if the engine might actually die when this happens.  Instead it revs back up
again to the normal idle speed after a couple of seconds.
         This occurs in the same way when the batt switch is on #1, BOTH, or
#2.  
         The same effect (drop of a couple 100 rpms, voltage drop) takes
place with the engine pegged at a higher speed (1500 rpms) as well.
 
         Why is this happening?  Solenoid flaw?  Alternator problem (diode,
voltage regulator)?  I figure it must be something to do with the electrical
system as the engine runs normally and strong except for this.
There have been no other changes made except the solenoid replacement.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Randy Katz#249
Seattle, Bellingham
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