Engine Starting Problem & Glo Plug Solenoid

[lazybone]

On my boat the glow plug circuit ran through the start keyswitch.  Before I installed the solenoid my keyswitch had failed.  I'm not positive but I would wager that the reason it failed was the large amperage it was forced to carry for the glow plugs. 

[Ron Hill]

Caio: I doubt that the amperage was the reason for your key switch to fail.  That's the reason for the solenoid mod, because all that length (16ft?)  of only #10 or #12 wire hardily delivered any amperage when it finally arrived at the glow plugs!!

My factory key switch failed within the first year I had the boat and the engine only had 75 hrs!

I found that that plastic housed switch had a weep hole, but it was installed so the hole was up.  Don't know if that was the problem or just a poor grade switch.  The new replacement metal housed switch is still going strong and is on the second engine (first engine wore out @5000 hrs)

A thought

[J_Sail]

The current for 3 glow plugs has been estimated at 18amp, which sounds right.  18 amps is on the high side for either a ignition key switch or a low-grade pushbutton, so it would not surprise me if it contributed to early contact failure, particularly when you add the corrosive marine environment. The two factors can be synergistic in a bad way, so it's reasonably likely that the addition of a properly rated quality relay (or continuous duty starter solenoid) would result in overall higher reliability.

[KWKloeber]

Not meaning to beat this to death,  but there's facts and opinions being thrown out that I can't pass up on. 

[\quote]
because all that length (16ft?) of only #10 or #12 wire hardily delivered any amperage when it finally arrived at the glow plugs
[/quote]


Q.?  Were the C34 harnesses 12 ga for the preheat circuit?  Maybe I'm off here, but the 1984 M-25 has a 10 ga for the #5 panel feed, #1 panel ground, and #2 preheat wires.  The remainder were 16 ga., including the #3 solenoid "S wire" (not good at all.)  I wouldn't think CTY/Seaward would decrease the size of the #2 harness wire for M-25s or XPS installed in a C34.

Nevertheless, fact-based and not opinion-based -- the preheat wire run itself isn't the culprit.  It's 0.6v drop, so it can be additive to something else that's wrong.  Yes a crappy preheat switch can be an issue.

Opinion:
It should be replaced with a quality watertight switch, like a 30-amp or 60-amp diesel equip switch with weather cover, such as:  http://www.northerntool.com/shop/tools/product_21065_21065

I'm open to hearing dissention/corrections about the below facts re: the glow plug discussion.

Fact:
A 16' harness (I believe the OEMs were a bit shorter) is 32' round trip.  Amperage is constant -- it doesn't drop, voltage drops.  3 plugs at ~6 amps each -- so the voltage loss is 0.59 volts, say 0.6 volts.  If your reserve battery is properly up to turn the starter, let's say 80% state of charge or, for sake of a starting point, maybe 12.6v (loaded,) the glow plugs (theoretically) receive about 12 volts (2v ABOVE their design of 10 volts.) 

Fact:
But, adding in some losses for "a few" connections -- the starter solenoid "B" terminal, key switch terminals and contact, preheat switch terminals and contact, glo plug nut, glo plug ground to block, (4) gummy bear bullet terminals, engine ground, selector switch, battery posts -- that's say 20? connections.  My count could be off -- Amazing how many isn't it?  Even at 0.1v drop per each connection (probably high) - that's 10.0v -- still at the glow plug design voltage.  But one does need to preheat for more than what seems to be the desirable 5-10 seconds. 

Opinion:
Of course the gummy bear connections V drops SHOULD be removed from this discussion anyway, otherwise the preheat mod is bizarre.  JTSO - some may disagree and that's ok.

Fact:
Adding the mod, eliminates the wire V drop (0.6v) and 6 connection voltage drops -- But adds 8 more connections (2 solenoid terminals, solenoid switch itself, 2 fuse terminals, 2 fuse plug-in blades.)  It also potentially makes troubleshooting just slightly more complicated (an additional circuit added, an electric switch, additional fuse -- e.g., what's faulty? the preheat switch and harness wire circuit?; the solenoid/relay circuit?; which fuse?)

Fact:
Solenoids do very very occasionally fail -- I recently went 'round with a customer with a no-start XPB with about 300 hrs on it.  I "pleaded" with him to test the preheat/fuel pump solenoid.  "Naw, it isn't that....,"  and so he tried troubleshooting/replacing about everything else.  Well it was and so wasted 3 days and 5 trips to the boat and NAPA, and bought an unnecessary fuel pump before he replaced the solenoid and..... Vroooooom. 

Fact:
KISS eliminates unnecessary failure (even unlikely failure) points.

Aside (and Opinion):
The stock XPB preheat/fuel pump solenoid is crap (OEM from Kubota) and the coil is easily burned out.
Replace it with a quality solenoid before it's too late you have an XPB.  JTSO - others may disagree and that's ok.

Opinion:
If there's an issue, the OEM is more-easily traced thu and troubleshot? at each point in the sequence. JTSO - others may disagree and that's ok.

Opinion:
The preheat mod is in some ways a bandaid -- it does allow owners to ignore other upgrades and maintenance -- eliminating the gummy bear plugs, moving the engine negative cable, properly terminating the harness wires, and maintaining the harness (corrosion, etc.)  I bet there may be more than one boat out there with the glow plug mod that still has the panel gummy bear plug?  Or even the engine gummy bear plug?

Opinion:
maybe my finger isn't as tender as others'.  Is it irony that sailors appreciate the SLO LIFE and simplicity, but want to add a more-complicated system in the quest to save 20-30 seconds time?  We're talking seconds here, not minutes!  
But YBYC of course, and if you want to do that (JTSO) a $10 40-amp plug-in, easily replaced in emergency, continuous-duty relay beats out a @20 hard-wired, continuous-duty, starter solenoid.  JTSO - others may disagree and that's ok.

Fact:
Start problems are oftentimes more related to no starter spin, than they are to no preheat. 

Opinion:
Everything related to that should be corrected first.

Opinion:
Better and best -- are loaded words when it comes to boats because it's all personal preference, but  -- maybe I'll call it a more "logical"? mod -- would be to install a slave relay (or solenoid if you must) tripped by the start switch "S wire," to energize the starter solenoid.   I'd be more concerned with getting full voltage at my starter motor solenoid, than the desire to over-voltage the glow plugs to save a few seconds at the dock or mooring.  And doing the 101 mods to the harness/gummy bears will get you more mileage in the long run than the glow plug mod, and will eliminate the need for the mod.  JTSO - another may disagree and that's ok.


Cheers,
Ken

[Noah]

Ken- just thought i'd let you know that the Forum doesn't pay writers by the word.   

[KWKloeber]

LOL. Ok, so sometimes I've been accused of verbosity.  Not this time tho - someone mentioned appreciation of "rich content" - just thought I'd  top off the coffers!  LOL

Oh would it be that I could convey complete facts in a 30 second piece like the media gives us to (es)chew on.  They know we can't comprehend anything more in depth than that. d:-[

kk

[britinusa]

I'l ask today's dumb one: JTSO ??? WDTM?

Joint Technical Standard Order


paul

[Stu Jackson]

I'l ask today's dumb one...

This may help in translation:

http://www.netlingo.com/acronyms.php][url]http://www.netlingo.com/acronyms.php[/url]

[Noah]

Sorry Paul-- nope.  "Just This Sailor's Opinion"

[KWKloeber]

Sorry Paul-- nope.  "Just This Sailor's Opinion"

Cousin to "JOSO"

[Ron Hill]

Ken : I read your epistle and agree with Noah.

For your data base - Seaward didn't get involved with the Catalina electrical panels until late 1990 or 1991.  By that time there were over 1000 C34 hulls produced (and an equal number of C30s & C36s).  The company that produced the original engine and main electrical panel was "Bristol Marine".  I had numerous conversations with their engineer Dave Weller over Hi- Temp alarms. (and the lack of !!)

In the spring of 1996 I finally installed the "Glow plug solenoid modification"  and wrote it up for the Mainsheet tech notes. I had already installed the "wiring harness upgrade" in about 1992.

I do recall trying to start the engine with 10 seconds of glow plug ON or slightly more and the engine not starting (on the first turn).  If I kept cranking for a couple of more seconds - of course most any diesel will start (if it has decent compression).

I surmised that glow plugs were cheaper than a new starter so I welcomed the addition of the solenoid and not keeping the glow plugs engaged for 30 seconds. 
I immediately noted that with the solenoid and the glow plug #6 wire length of less than 2 feet, 10 seconds was more than enough pre heat time to start the engine with only a  "tap" on the starter.

A few thoughts

[KWKloeber]

Ron,

Thanks for clarifying when Seaward got involved -- YES! mine was actually a Bristol panel (with a Hi temp alarm.) 
But my point was merely that in 1894 the preheat was 10 awg, so I doubt that anyone (Bristol, CTY, Seaward or XYZ) would reduce it to 12 awg for the C-34s.

I wholeheartedly agree with you that if someone can't deal with 30 seconds preheat time then the mod works around that.  That's a personal choice that one has to make, but it's unnecessary to operate our engines (i.e., following the Operator's Manual,)



But "glow plugs versus a new starter" is a false choice.   Let's ignore that the plugs are 10 volt.  So that others decide based on facts, the choice is "a new starter versus following the manual."  Is that a decision most owners need to weigh?  What's wrong with just following instructions? 

The parallel choice is -- to follow instructions, or shortcutting them with a more complicated system and potential failure points.  If saving a half minute is more important than KISS, then again the mod is probably the way to go.

Tongue in cheek:
How about other mods and fixes for those who want to work around instructions?  A system to 'dump' the muffler in case we crank more than 30 seconds?  That would save the time opening and closing a petcock - a lot more than a half minute.  Or a fail-safe fuel cut off to shut 'er down down if she overheats?  Or an over-RPM watcher?  Then we'd need to follow even fewer operating instructions. 
 
(another) Fact:
The capacity of 10 awg is 51 amps vs. the 18 amp load.  The drop is 0.04 v -- irrelevant when using a 10-volt glow plug and equates to 10.02 seconds finger time, versus 10 seconds using 6 awg or 8 awg.  Not a problem using larger than 10 awg -- but like the mod itself -- just not necessary.

Cheers,
kk

[britinusa]

Sorry Paul-- nope.  "Just This Sailor's Opinion"

IMHO, that's OK.



Paul