Multi-year Ignition Conundrum

[U404S]

Hi everyone,
Firstly, has anyone seen the $29,000 M37 on eBay right now? That is about the cleanest I’ve ever seen. It’s worth a look. Not for me, however; I’m still committed to my own endless restorations.

As to my ignition problem, I will share two years ago my mechanically near-perfect 1952 M43 ambulance would occasionally leave me stranded. Each time I would take it home and conclude the spark either wasn’t strong enough or not there. If I changed the coil it would start right up and I’d be good for a while. Sometimes after a week or so it would start with the “bad” coil and would run fine. The last time it happened there was no spark at all on a new-to-me used OEM coil. That was two years ago whereupon I got frustrated and garaged it until this past weekend. By the way, it never just stopped running. It only failed to restart after sitting for a half hour or so after shutting it down.

Fast forward, I decided to go to work on it yesterday and what a surprise, it started right up and purred like new on the old coil that left me stranded two years ago. So, I made sure my wife was by the phone and I had my tow bar ready and then I went for a nice long ride. No issues; even hit the siren a few times, what a blast. It even started when it was hot and after I turned it off. It ran well on the two-plus year old gas a well.

So, I’d like to think it is fixed, but I don’t think it is.

I’ve checked all of the distributor connections, the air ventilation system, ignition switch, cap, rotor, etc. - spark plugs are clean. I will mention it has the Pertronix kit in it. I used Pertronix igniters for more than a decade in an old Ford 9N tractor, a 1978 Fiat and three different Unimogs. I’ve never had Pertronix strand me, although I burned one up leaving the ignition on once on the Fiat. I’m thinking about buying a new Pertronix in case mine is failing intermittently, but I’ve never heard of that happening. Can anyone think of something I am missing that I need to check?

I’m thinking that I must be bumping something that fixes the problem when I change out coils and that my coils are all actually fine. In fact, when I test the resistance, all of the coils put out different readings yet they all work fine……from time-to-time.

When it is running, it is so smooth and hits on all cylinders, and fast off the start (for a 1952 M43), no smoke either.

Any advice would be appreciated. Cheers, Jerry

[Cal_Gary]

Wow Jerry, thanks for the updates!

I hate gremlins like the one you've described. I can't offer much guidance because what usually happens is you start swapping out components hoping to nab the buggy one, and most often, that doesn't work. If troubleshooting hasn't conquered the problem, my only counsel is to carry spares of what you think it might be (coil, Pertronix, etc.) along with the tools to replace them if you have to pull over while in route. Electrical stuff is such a PITA-could be a bad ground, worn wire, periodic short somewhere, etc. I replaced all of my electrical stuff and harnesses except my turn signal switch, and only for one blown signal motor I've not had any electrical issues. It's only stopped running in route once, when one of the spade terminals on the ballast resistor came loose. Fortunately I had room to pull off and stop, and spotted/solved the problem in a few minutes.

You've just got to keep driving it to eventually solve it. Once I got mine on the road I continually feared breaking down so I carried some spare parts and tools, along with a multimeter and my cell phone, with numbers to my insurance (Hagerty) and their towing coverage. Now years later, with fingers crossed, it's a reliable driver whenever I need it-we actually ran errands in it last Saturday

Good luck, and keep us posted!
Gary

[U404S]

Thank you Gary,
Well, Saturday it was pretty rainy so I spent the day cleaning connections, tracing and testing wiring. The wire coming off the radio suppression filter was in rough shape (I think that’s what the thing at the bottom of the distributor housing is). It had been covered in electrical tape. I replaced the whole device with a spare I had. Other than that, there were no other discoveries.

So, I went for a few rides toward evening Saturday. No issues. Sunday my wife and I jumped in the ambulance and drove a 30 mile circle around Jacksonville. Everything went well. I am carrying an extra coil; have not needed it yet. Still need to get a spare Pertronix. I’m not declaring it fixed yet, but it might be….

With the extra confidence, I put a new battery in my M37 today and tried to get it running too. This truck has is converted to 12 volts and has an Accel electronic ignition kit. I have not driven it in years. Before starting it I drained the carburetor, filled the tank, changed the fuel filter, mixed in some fresh gas in the tank and it started right up and ran nicely. I’m excited about getting going on this one again.

Unfortunately, this truck still needs a lot of work; I stalled on it years ago. I bought it in disassembled, frame-off, project-state with a trailer full of parts. I’ve made a lot of progress on it over the years in that the drivetrain is in (and works) but I still have to put the front fenders on, the grill parts, the headlight assembly, some more wiring and the windshield assembly. Unfortunately, all of the fasteners from the truck are mixed together in coffee cans so I use the M43 for identifying things and as a pattern for putting this M37 together.

Cheers, Jerry

[NAM VET]

sure hope your '43 continues to run like a champ. As for mixed fasteners, on may truck, which had only some surface "patina" and wasn't rusty, I cleaned and used only the Dodge Marked bolts where they show, mostly on the front bumpers and winch and such. For just about everything else, I used grade 8 fasteners from Fastenal. Just cleaner threads. I also have a bucket of fasteners, and one of these days will use a rotary vibratory cleaner on them. I was able to get plenty of the OEM square washers from Snake River before they closed.

Like in any restoration project, I have accumulate a lot of "spares" and extra parts. I am going to replace my 180 T state with a 160, and found a 160 in my boxes of spares. Time to crawl under my truck, and grease the 455+ Zerks there.

Best wishes, hal

[John Mc]

Nam Vet - do you have a hot water heater in your truck? That's usually where the 180˚ thermostats came into play. I have a 180˚ T-stat in my truck with a MUTTS heater, and it works well. I don't think I'd want it running any colder when operating in weather requiring the heater (especially since most of the seals are gone around my windows, making for a bit of a breeze even with everything closed). The only times I'm had temperature issues in hot weather was when my thermostat started sticking - happily, that only happened a few times, then it stopped having problems.