Universal M-18 Two-Cylinder Diesel Won't Start

[Steve W]

DeepFrz, nice catch! I did a quick test by bypassing the glow plug circuit and touching a Positive wire to the glow plugs to see if they would heat, which they did, but it did not get hot enough to start the engine. Test wire gauge was probably too small. I discovered the melted wires the day after I wrote the original post. Still tracing, evaluating, etc.

[Steve W]

Success! The shorting problem was one glow plug had completely shorted out and the other glow plug would get warm, but not red hot on the tip. The shorted out GP caused the wires in the GP circuit to melt between the preheat button, ignition and amp meter. I also discovered, thanks to Mainesail, the wiring harness "trailer connector" had melted slightly next to the positive and alternator/amp meter wires. Not sure what failed first. There were no fuses in the positive wire going to the panel, despite the wiring diagrahm showing fuses.

Using advice gathered here and from the Newport and Catalina owners sites. I ran a new ground wire, amp meter wire and positive wire around the harness and installed new ignition switch and new glow plug switch & wiring as well as new wiring behind the panel.
And the damn glow plug wire still got scalding hot, the top of the glow plugs were hot and still no start. Finally decided to pull the glow plugs and used an ohm meter to test + a manual test and they were bad. My best guess is that there was enough resistance causing the bad glow plugs to get hot externally, that it fooled me into thinking they were working, so I concentrated on finding a short and rewiring. Installed new ones and it fired up immediately.

I plan to use Mainesail's advice and get rid of the amp meter circuit and install a volt meter, eliminating the long wiring run. Additionally, I'll add a solenoid or relay in the glow plug circuit and get rid of another long run high amp circuit.

And yes, I did add a fuse in the postive line that runs to the pane, , next to the starter soleniod and I am researching fusing at the batteries.

Thanks again for all the great advice. This forum is a wonderful resource.

Steve

[Chief Engineer]

There is always a short in the glow plug circuit. That's why they glow.

You are lucky that your friend didn't burn the boat down or blow it up.

You NEVER use ether with glow plugs!!!!!!!!!!!!!!!!!!!!!!

[Steve W]

Chief, I knew spraying starting fluid into a diesel intake was not a good idea. I remembered that spraying a very small amount on a rag and holding it near the air intake was a better way to go. Did not try to activate the glow plug when using the starting fluid, if that makes a difference. I knew there is normally a short in the glow plug circuit, but this tuned out to be a total dead short (I think that's the term) causing the wires to get too hot to hold, melt, etc. Now the wires don't even get warm when activating the GP cicuit and it starts right up. Amazing how such a simple part can cause so much drama.

[Chief Engineer]

Now I understand

[casual]

You are lucky it didn't act up sooner.The wires running from the starter selinoid to the pannell are to small 14 gage I think,Mine had all the same symptons your does immediately after installation . Took me a year to figure it out,I replaced the wires with 10 gage and the fuse holder at the pannell with a marine type holder ,Still ok after 19 years.

[SkiprJohn]

Really glad you got it sorted out. Isn't it wonderful when those things fire right up after you diagnosed and cured the problem. Joyous day.
kind regards,