M37 Mystery Problem

[copperline]

Hello all. I have a bizarre M37 problem that I can not figure out. I'm hoping you smart folks might be able to point me in the right direction.

Firstly this is a 1952 M37. Mostly original but it was converted to a fire brush truck.

I have done extensive repairs to this truck. New wiring harness, sealed gas tank, flushed out all fuel lines, rebuilt the carb on and on. The truck is in great shape.

Now to the problem.

The truck was running ok (not amazing) but drivable. The truck shut down and I couldn't get it restarted. I checked the fuel and it was bright orange and cloudy. I cleaned everything out, flushed the system, and put everything back together. New gas with a bottle of HEAT to be safe. Still wont start. Wont even cough. Starter fluid does nothing. So back to the drawing board I went. Checking everything. Fuel in the carb, good spark etc etc. Nothing worked. Turns over strong and thats all she does. I checked the ignition 24v and its present, checked all 6 plugs for spark all good. Pulled the cap and checked all of that, all good. Even rotated the timing a little just incase the distributor got knocked around. Nothing does anything.

Then my daughter came to visit for the summer and the truck sat there for two months. I had not touched the truck in that time. Then three days ago i got in and just for the heck of it tried to start her up and she fully started right up. Instant too. Ran well enough that I drove her around the ranch, up and down hills, went through all the gears, and she ran great.

Brough her back into the shop for the night. Came back the next morning and nothing. Exactly like before. Turns over strong and thats it. Not even a hint of wanting to start.

I thought that maybe i was having a grounding problem so I pulled the engine grounding strap off, cleaned up everything and put the strap back on. Also re-did the battery ground just to be safe. Continuity from the chassis to the engine block is perfect.

So thats where I stand. I am clueless as to what to check next. I have a feeling its something really simple but it eludes me.

I hope someone here has a clue, because I sure don't.

Thank you all!!

 

[GopherHill]

If the starter is spinning the engine well, check the compression. If the compression is poor, pull the lfter cover and observe the valves for proper action as soldier B works the starter. May be as simple as rust on the valve stems after disuse. If that is the problem, spray penetrating oil in the plug holes . Let that work for a day or two.

I have seen this happen on two flathead engines.

 

[NDT]

No ideas here but what I would do in your situation when it won't start is to remove all 6 spark plugs and reattach the cables and see if you have a nice blue spark at all 6 plugs.

 

[copperline]

If the starter is spinning the engine well, check the compression. If the compression is poor, pull the lfter cover and observe the valves for proper action as soldier B works the starter. May be as simple as rust on the valve stems after disuse. If that is the problem, spray penetrating oil in the plug holes . Let that work for a day or two.

I have seen this happen on two flathead engines.

When you say "lifter cover" what exactly is that? I have not heard that term before. Looking down on the engine all I see is the head (where the spark plugs screw in).

Could you clarify?

 

[copperline]

No ideas here but what I would do in your situation when it won't start is to remove all 6 spark plugs and reattach the cables and see if you have a nice blue spark at all 6 plugs.

I ordered a set of new plugs. Who knows how old these are and they are pretty beat. I don't think its the plugs but at this point ill try anything.

 

[Roller]

As stated above, check the compression.

Frank

 

[Squirt-Truck]

Condenser has died. Replace.

 

[GopherHill]

When you say "lifter cover" what exactly is that? I have not heard that term before. Looking down on the engine all I see is the head (where the spark plugs screw in).

Could you clarify?
That is the rectangular cover under the exhaust manifold. The operator's TM has good instructions. Perhaps download and print what you need.

 

[dougco1]

Condenser has died. Replace.

I agree fully with Squirt. You need 3 things for internal combustion, gas-air & spark. If you don't have spark you won't have combustion. Replace the condenser and it wouldn't hurt to add new plugs and wires.

 

[frank8003]

coil died?

 

[John Mc]

In his initial post, he stated that he has "good spark" and "checked all 6 plugs for spark all good". If in fact that is correct, wouldn't that tell us that the coil and condenser are good? (unless they have intermittent problems).

 

[GopherHill]

I saw that the truck did start and run once in the interim made me suspect a loss of compression issue. Especially after ignition system was checked. Did you try a spray of starting ether?
Like I mentioned, pull the plugs and spray P.B. Blaster or the like in the spark plug holes directed towards the valve side. Let it sit for a day or two before just throwing parts at it without a compression test.

 

[frank8003]

I Have seen "intermittent" on coil outputs.
Since 1950 just changed points condenser distributor cap coil fuel
and that silly little wire to the distributor that makes it all go.
That stupid little wire gave the run around many times, broke inside, vibration we guess. Silly runs good and then no run = intermittent BS.
Most engines seen would run even with zero compression in there some place.
Pull the valve covers and watch it all work. Things need to go up down up down.
You have no pitchers?

 

[Squirt-Truck]

Condenser...coils die when hot, condensers are intermittent.

 

[Squirt-Truck]

Update?

 

[GopherHill]

Yes, please update on your progress.

 

[JD4044M]

They flood super easy pull the plugs and see if there wet and check for a good spark.

 

[copperline]

Here is the update. I checked the coil and all of the measurements were fine. Pulled all of the plugs and they were wet BUT that might have been from me checking compression (and adding oil as part of the checking process). I decided to order new plugs.

Got the new plugs this morning (autolites) and put them in. Turned the key and she rumbled a little and almost started. I really thought this was going to work.

Trying to re-start her and nothing. Same old thing. Round and round she goes with zero interest in starting. Nothing. Not a cough.

I pulled all of the plugs again and they were not wet but not dry either.

I then checked the spark using one of the new plugs and it was a yellow/orange/white color. Certainly not blue like they say it should be.

I am not going to buy another one of those chrome coils that everyone says are trash so I went ahead and bought a NOS coil from Midwest (very expensive). Also ordered a new distro cap and rotor just to be safe.

FYI I did have some rotor and distro cap problems. It seems that the original rotor on the truck was a bit shorter on the shaft. This created a rust line on the shaft. When i put in the new rotor it naturally stopped at that rust line, but that rust line does not match the new rotor. So the rotor was sitting high and actually hitting the terminals inside the cap. I sanded the rust line down and put a bit of grease and the rotor finally seated all the way down.

So now I wait for the new coil and see if that makes any difference.

 

[snowtrac nome]

most important check and adjust your point gap if you don't get proper coil saturation you will not get a hot spark. i like doing the condenser with the points the condensers job is to prevent arcing and material transfer on the points

 

[copperline]

I have the electronic ignition on this truck. Petronix MV-161A