Glow Plug Question

[Ron Hill]

Robert : Thanks for your conclusion and explanation of why the M25 type cylinder engines need glow plugs!!  Your M35BC engine already has the glow plug problem solved!!  However the factory installed M25/M25XP engines do NOT!!

You are correct about the longer(15ft run), but you didn't hi-light the size of the wire - 15ft in #16 gage wire and 2/3ft in #8 gage wire!!  That'd one hell of an amperage difference and battery draw down in 30 vrs. 3 seconds !!!!   

The saddest thing is that it's an upgrade that only costs about $25 !! and is easy to do!!   

A few thoughts

[Robert Mann]

Ron you are quite right.  If my boat had the direct wired plugs, it would bother me to no end, I would add the solenoid update. 

Just be thankful we have glow plugs, times past we used flame starters.  Basically a fitting in the intake with a resistance wire coil that was 12 or 24v activated, into this we ran fuel and created heat in the intake manifold to aid starting.  Made by the Prince of Darkness themselves CAV Lucas, who else?

[KWKloeber]

[edit]  PS: Bob/Ron, I've seen THREE of the wonderful unnecessary start/fuel shutoff/preheat solenoids FAIL.
What do owners do then?  When they need to start within the precious 2-3 seconds (because before that point one couldn't wait the 25 or 30 seconds)?  No one wants to address that elephant in the room; just ignore it.

...the solenoid is also interesting in that without it the circuit runs through the panel, this has to cause some voltage drop due to wire length.

YES YES YES EXACTLY.  And that's DESIRABLE.
NGK says, "Don't go above 10.5 volts on our plugs."

Bob,

With all due respect to everyone's right to an opinion, this is what I mean about "Koolaid" spreading. 
Many incorrect "facts" and misconceptions float around about the OEM preheat circuit.  And folks snatch onto them or make up new ones to espouse why it's "bad," based on incorrect assumptions that are formulated from incorrect "facts" to being with. 
Then someone cries "Yeah Yeah, Thank you!" (for supporting my own nonfactual statements.)   It's a vicious cycle that goes on and on.

Trying to keep a technical discussion, factual:

...the voltage dips the amps go up. 

Not factual.  Resistance in the plugs (1.6 ohms) + resistance in the wire (0.07 ohms) controls the amps.
Your V/A relationship is also not factual.  Mr. Ohm says so (it's a law, not just a good idea.) 
Amps = Volts / Resistance, ohms.  i.e., if the supply voltage drops from 12.5v to 10.5v, the amperage doesn't increase it DROPS 16%. 

Could be the wiring might not handle that so well.

Not factual - the GP circuit is 10 awg not 16 awg as Ron says (the S wire was 16 awg) and 10 awg can handle 51 amps (in the engine compartment), and like 60 amps outside the engine compartment.

...if an engine manufacturer added a solenoid to this circuit there was a potential (no pun intended) problem.  It certainly wasn't done for our convenience!

Interesting assumption but that ain't the history. 
Universai Medalist never added a GP solenoid. 
And Westerbeke didn't ADD a GP solenoid.  No eureka! moment there.
Wb engines "always" had one because JDW had the engine shutdown (low oil pressure) -- either the pump shutoff or an optional fuel line shutoff.  Wb simply slapped on it's long-standing wiring scheme when it bought Universal -- **Those are the "A" (25XPA) engines**.  Anyone who believes that Wb wiring (non ABYC compliant, by the way) is the gold standard that's another topic for discussion.  IN FACT, Catalina didn't like some of Wb's scheme and made them change it for our boats.  I think Ron can tell you what he thinks of Westerbeke's wiring.

The solenoid is there because it's needed for the engine shutdown, and the alarm, and yes, powering the GPs when basically power to the engine is shut off when there is no oil pressure (that is before starting,) not because Wb had a eureka moment about glow plugs.

[KWKloeber]

Look at what you have with out it

Ron,

I believe nearly 100% of your arguments against leaving the OEM preheat are, well, "not factual."   i.e., they're simply untrue. 

I'm not trying to change your or Stu's mind.  What I said is others NEED to have ACCURATE FACTS (in short supply) and then weigh the downsides.  And (instead of Koolaiding) decide from FACTS if that gamble is worth 10 whole seconds and if those are necessary (not just desirable.) 

I address your statements (if anyone cares to know the facts.)  If I misconstrued anything you said, please correct me:
https://c34.org/bbs/index.php/topic,10744.msg83677.html#msg83677

I never ever said a shorter preheat is undesirable.  However, decide using ACCURATE FACTS.

(As you say) A couple thoughts about being necessary -

When firing up in an anchorage, what difference if one starts to weigh a situation for 25 seconds WHILE preheating?  See what I am saying about it being "unnecessary" when one sits down and honestly weights the situations?  A peace of mind is the difference -- but not a necessity.

When sailing and one needs to get 'er started (within 10 seconds rather than 20 seconds) to get out of the way, would you say the skipper is "maintaining a proper watch"?

What would you say if a powerboater had a colision because he/she misjudged you by 10 seconds?

[Noah]

Religion, politics, climate change, face masks, anchors, glow plugs....???? The list is getting longer...

[mark_53]

Question to those who have made the solenoid conversion.  Have you burned out any glow plugs since doing the mod?

[Noah]

Been 4 years and, nope. Fingers crossed.

[scgunner]

There seems to be a lot of passion involved with this topic considering we're just talking about starting the motor. I get the long wire run argument for favoring the solenoid addition, but I think at some point we might have to concede to the possibility that the guys that built this boat just might have known what they were doing. As for me, I'd rate my stock ignition system as excellent, even with my 33 year old glow plugs(the thing that started this furball originally), so I don't see the need to make any changes.

Jim, FYI my M25 has no interest in firing up unless it gets some glow plug lovin' first.

I do love this board, along with a spirited discussion on a topic that was heretofore unknown to me, I also learned a better technique for starting the motor.

[Kyle Ewing]

To add another data point, my 1990 only needs 10-15 seconds of glow plug to start from cold.  I have the Catalina Direct wiring harness upgrade--first thing I did when I got Donnybrook--but otherwise it's stock.  I've thought about the solenoid but have other priorities.

[KWKloeber]

@Noah - poliglow vs wax?

@Kevin

To your original question, you can also check the resistance, wire terminal (wire removed). to the grounded case. If it's 1.6 ohms, give/take a little you are ok.
Caveat- that R is from the Kubota service manual, not from NGK or verified (but that value does make sense given the v and a ratings. Another thing - if the tip gets carbonized and gunked up in the "tunnel" into which it fits, that can affect operation. So, if they heat as I described and R checks out, before ass/u/ming she needs a voltage boosting mod, the GP should be removed and that checked out.

The only passion/dog I have re: this is, "(actual) facts first, then decide"

[KWKloeber]

@Kyle

You bring up a very good point. I alluded to it (w/Ron's 30sec vs 3sec,) but didn't give it enough spotlight. If one had slow preheating and did a harness upgrade and the same time (quite likely I'd imagine) installed the preheat mod, one could very easily conclude that cheap, $25 mod was "necessary." 
But we know that Correlation doesn't prove causation.

As you did, upgrading the harness and getting everything up to snuff — maybe just maybe a mod isn't "necessary" (except say for extreme temperature locations.)

@mark

I'd suspect that they would degrade more rapidly over time, not completely fail at once.  But as I pointed out it's not that huge an issue for us due to the relatively few times our engines are preheated (say compared to an automobile or truck or construction equipment) over a year.

I didn't get into these weeds, but since at least some find a technical discussion worthwhile here's some tidbits. NGK has told me it has ceramic plugs much more resilient to over-voltage/over-current. Also that it has developed self-regulating plugs (so instead of a resistance box externally as Kubota installs,) the plug itself controls overheating when it gets over voltaged.

No, neither series are available to replace the Y-103V plug.

[Stu Jackson]

Question to those who have made the solenoid conversion.  Have you burned out any glow plugs since doing the mod?

No, maybe 20 years ago, at least 15.

[Ron Hill]

Ken : You need to remember that I've been talking about the glow plug mod. in only the M25/M25XP engines.  I don't know of any one that installed that glow plug mod back in the early 1990s has ever had a failure?!?

As C34 Mainsheet tech editor I had one hell of a time figuring out what Westerbeake had done to the M35 engine?  The 2 prong oil switch??? had us baffled for awhile!!   

In fact when I installed my NEW M25XPB engine, I took all of that old mod (+ the single pole oil switch) from the old engine and installed it all on the new engine.  It all is still going 24 years later !!!!
I just couldn't stand the thought of that goofy glow plug, fuel pump, oil pressure "Lashup" that they installed on the M35BC and M25XPB engines. That's why I removed it!!   
Don't know how many posts and questions have come up over that GOOFY "Lashup"; which is NOT necessary as the C34 engine will still keep running even if the fuel pump fails ANYWAY!!!!!

A few thoughts

[mdidomenico]

i've read through this thread with interest as i will add a solenoid to my engine when i rewire it over the winter.  seemed like a good idea.  i can't say for sure one way or another, but the 10.5v requirement is something i don't understand.

i can see the NGK-Y103V replacement plug mentioned does seem to list 10.5v in it's specs.  i unfortunately can't find the spec for the OEM plugs that came with my engine (and are still in it).  I'm wondering if the universal glow plugs are actually higher voltage.  and since most people haven't changed out there glow plugs, that might explain why those that have done the solenoid mod haven't blow out their plugs

it seems odd to me to add a component to a system that requires a max voltage that is far below normal battery voltage, but doesn't include some sort of a voltage regulator to ensure it doesn't exceed the spec.  relying on a voltage drop over then length of cable is fine, but i think we can do better.  in the same vein, lets say someone wanted to add the solenoid to the engine (for whichever reason), but also wanted to regulate the voltage from the solenoid down to 10.5v for the plugs.  any recommendations on a component to add?

[mark_53]

in the same vein, lets say someone wanted to add the solenoid to the engine (for whichever reason), but also wanted to regulate the voltage from the solenoid down to 10.5v for the plugs.  any recommendations on a component to add?

I'd measure voltage at the plugs first then add a longer wire, possibly to the panel and back to reduce the voltage to 10.5v. lol