diesel starting issue

mikesh

.
Mar 16, 2011
4
ericson 30+ coyote point
My sailboat has a Universal M3-20B diesel. Just recently it has been hard to start. When i press and hold the button to warm the glow plugs the gauges on the control panel are showing power.
After the 10 second warm up procedure I press the start button whilst still holding down the warm up button (The correct starting procedure on this engine). As soon as i press the start button all gauges (Amps etc) drop to zero - dead. When i release the starter button the gauges come back to show current. The batteries are good.
After several repeats the engine starts and once warm it is ok but I'm worried in case this gets worse or i need to start a cold engine in a hurry.
Any suggestions are welcome.
Thanks,
Mike
 

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
It certainly sounds like an electrical issue, high resistance in the harness, as pointed out by Richard; or perhaps, poor ground or starter connections, or just a worn-out battery.

How old is the battery?

Things that helped enormously on my M25 in a Catalina 36:

  • Eliminated molded wiring harness connection, replaced with a terminal block;
  • glow plug solenoid near engine;
  • always fresh, dedicated engine battery.
You don't need a large battery to start these. The tractors they were used in often have U1 "lawn and garden tractor" batteries. But, it needs to be good, if it has too much internal resistance it will do what you describe. After 10 seconds of glow, these should roar to life after a couple of fast revolutions from the starter.
 
Sep 25, 2008
7,075
Alden 50 Sarasota, Florida
Start with the easy stuff - remove and thoroughly clean every connection in the circuit beginning at the battery
 
Oct 22, 2014
20,989
CAL 35 Cruiser #21 moored EVERETT WA
@mikesh a big :plus: on the above advise. Especially @Don S/V ILLusion . Start with the easy stuff.
It sounds more electric and connections are often the culprit. A whole lot easier than a replacing of the electrical wiring system. But if there is a safety issue then perhaps it is time to address the wiring. It is your boat and your choice. Perhaps getting it running for this years season and then take the time in the winter to replace the harness.
Do not just let it go. As you say, when you need the motor to start watching it sit there is no good.
 

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
@mikesh ...But if there is a safety issue then perhaps it is time to address the wiring.
There is, I think, with the old, molded wiring harness connector. Mine was burnt - a fire waiting to happen.

You don't have to replace the harness, you can cut off the molded connectors and use a terminal block.
 
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Apr 1, 2017
34
Laguna 30 Newburryport
Measure the voltage at your starter secondary ( the small wire coming from the start button ). If voltage is too low there the starter solenoid wont engage and you'll just send all power to your glow plugs. I cleaned the "trailer" connectors mentioned in the link on the other post, the ground wire on the engine block and a bunch of the crimp lugs on the back of my dahboard panel.
I used fine emory cloth and a bottle of de-ox-it 100 from the electronics store. ( This stuff is excellent at removing corrosion - expensive but worth it ).
Now the boat starts up every time - I hope this helps
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
Probably the molded trailer plugs if they're still there. You don't need a terminal block, just cut out the plugs and replace with heat shrink butt connectors. They only put the trailer plugs in to make installation easier. Once the engine is in you don't need them anymore. I rewired my engine with all new wire continuous from panel to engine, no extra connections anywhere. Much less chance of problems that way. Actually I bought it used and it didn't have a harness so I had to do it that way.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
In addition to the trailer plugs mentioned several times, my guess is you still have a functional amp meter and no glow plug relay mod. @Maine Sail has a good write up on fixing these things
https://marinehowto.com/universal-diesel-engine-wiring-harness-upgrade/

Look around c34.org for a description of the glowplug relay mod.

For a very short while the seaward motor panels were wired to require glow plugs on to crank the engine. This required two hands and was deemed very dangerous in bad weather so the removed the interlock. Normal Universal starting is to not run glow plugs when cranking

Incase we are all full of it here and you’ve done all the mods, have good wiring and battery it is possible one or more of your glow plugs has bit the dust. To check measure the amperage out of or into the relay (pin 30 or 87) it should be 36A. Glow plugs are inexpensive if you don’t by the universal brand. I think I paid about $6 each last year.

Edit: the M3-20B is a Marineized D-722E Kubota
Les
 
Last edited:

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Probably the molded trailer plugs if they're still there. You don't need a terminal block, just cut out the plugs and replace with heat shrink butt connectors. They only put the trailer plugs in to make installation easier. Once the engine is in you don't need them anymore. I rewired my engine with all new wire continuous from panel to engine, no extra connections anywhere. Much less chance of problems that way. Actually I bought it used and it didn't have a harness so I had to do it that way.
The terminal block becomes a convenient place to probe circuits when de-bugging, with a meter probe, or even clipping on a test lead.
 

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Incase we are all full of it here and you’ve done all the mods, have good wiring and battery it is possible one or more of your glow plugs has bit the dust.
Excellent thought, Les! (Last time I bought glow plugs was for my M25, $5.40 each from clubplug.net.)
 

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
For a very short while the seaward motor panels were wired to require glow plugs on to crank the engine. This required two hands and was deemed very dangerous in bad weather so the removed the interlock. Normal Universal starting is to not run glow plugs when cranking
My 1996 Tartan has a Westerbeke that's still wired this way. The Westerbeke Admiral Panel and Captain Panel both have the starter switch energized through the closed preheat switch. I take it many have rewired this so that one can release the preheat switch to depress the starter switch.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
I have terminal blocks at the engine - but replace the hokey european blocks that CD gives in the kit with WeatherPak connectors at the panel - 2 each 5 pin connectors pointed opposite ways with inputs on one and outputs on the other (mostly). I also have a bigger terminal block with jumpers so 6-8 terminals each at the engine for ground, power, switched power (alternator excite) - and remove all the parasites from the engine.

My engine never fails to start even after the glow plugs haven't gotten power
for 5-10 seconds.

I got my glow plugs from the same place
 
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Dec 25, 2000
5,702
Hunter Passage 42 Shelter Bay, WA
the M3-20B is a Marineized D-722E Kubota
Our Genset is a Kubota 8MDKDR31457C three cylinder diesel that requires glow plug action before she will start. But start she always does as long as everything else is working (another story). Well built and very reliable.
 

MitchM

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Jan 20, 2005
1,011
Nauticat 321 pilothouse 32 Erie PA
if your boat has a start panel in the cockpit, you may be seeing a lot of voltage loss from battery thru the wires up to cockpit switch then back down to engine starter motor. measure volts at battery + and compare to + into starter . RX: put a heavy duty momentary start switch (rated for proper amps) between battery and soleoid, bypassing the cockpit system. i put this in and it's lso very convenient to start the engine from down below instead of climbing up into the cock pit.