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M37 Mystery Problem

copperline

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26
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Location
Nashville, TN
I have ordered a new fuel pump and some more Rotella.

I'm starting to think that this might be the issue. This is making the most sense so far. Still have the rough idle situation but maybe that is also related to having fuel in the oil.
 

Bill Nutting

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This sounds familiar to me. There is a filter capacitor located at the bottom of the distributor housing. It is where the 24 volt ignition wire is connected to the distributor. There is a small square plate with four screws that hold what looks like a connector. It is actually the filter capacitor. This what worked for me a long time ago:
Remove the coil. Remove the filter capacitor (access from under the truck). You will see what looks like a tin can with the 24 volt wire that was connected to the coil coming out of it. I was told to cut the tin can off with a hack saw. Just cut through the tin, don’t just hack through it. Pull the can off and expose the center wire that runs through the capacitor. The capacitor is full of a gooey substance. Cut the center wire shorter (it’s a sold wire) and solder a wire to it about 7” long. This is your new 24 volt supply to the coil. Mount the little square plate back on the distributor housing, reinstall the coil. I had a similar issue when I got my M37 in 2001. This mod lasted until this year. I did away with the internal Chinese coil and made a modification that allows me to use a standard 12 volt coil mounted outside of the distributor. I have another post that has pictures of this mod.
Heat will kill those cheap chrome coils. I’m not buying any more of them...
 

copperline

Member
47
26
18
Location
Nashville, TN

None yet. Waiting patiently for the new fuel pump. Midwest said that the regular manufacturers have stopped making them so I had to search elsewhere. Oddly I found the pump at Summit Racing and they said it would ship on the 18th.

Everything else is done just waiting for this. Replaced the fuel/oil and thats ready to go.

Boy I hope this works.
 

copperline

Member
47
26
18
Location
Nashville, TN
Here is a short Friday night update.


I had already drained the oil and left the plug out and fill cap open for a few days to let any remaining fuel evaporate (maybe). I have since filled her with new Rotella oil.

Got the new fuel pump today and put it in with no issues. I did mark the dipstick to know if fuel is still getting into the crankcase.

Got in the truck and she started right up and idled better than ever,

Then she peetered out and wouldnt restart. I pulled every plug, used a long lighter to clear out any gas from each cylinder and I used a propane torch to cook off each plug. They were certainly black, sooty and smelled of fuel but that may have been from before.

Got all the plugs back in and she wont start. Wont even cough.

I have only given this maybe an hour of screwing around with this after getting the fuel pump back in but thats where we stand.
 

copperline

Member
47
26
18
Location
Nashville, TN
Well..... I just don't know what to do next.

I replaced the fuel pump thinking that was the source of the fuel in the crankcase. That may or may not have been the case because she wont start.

Right after I put the pump in she started really well then petered out like usual. I thought it was residual fuel in the oil or other plug fouling.

I pulled every plug and cleaned them well and let the cylinders air out some. Got it all back together and nothing. Just turns over.


Its been about a week since I did that and nothing since.

I really don't know what to do next.

What I cant understand is if there was a valve problem or compression problem or ignition problem or anything like that, why does she run for a few minutes then crap out? Any one of those issues would be from the beginning, not after three or four minutes.

I have no idea. Pretty bummed about this actually.
 

glcaines

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I have to tell you, I have had two different vehicles with Pertronix ignition systems. Both Pertronix systems failed and the failure mode for both sounds virtually identical to your situation. I trashed the Pertronix systems in both, going back to original points and condenser and never had any more problems. I spent huge amounts of time troubleshooting everything. Since I had spark, I was convinced I had a fuel problem. Sometimes they would run great. Other times they would run rough. Sometimes they would run great until I shut down and then they wouldn't re-start until hours or days later. I got marooned miles from home on more than one occasion.
 

Karl kostman

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I had an issue somewhat similar to this with my M37 and it was a 52 also (not the issue) but I got it out of storage and ready to sell and it had run perfectly the Fall before and this Spring when I went to start it she fired right up ran for a bit and quit then would not restart. I went through the fuel lines and filter all was good and I was getting good fuel flow out of my electric fuel pump to the carb so I figured the fuel had gone bad so I drained the tank and put in 10 gallons of new fuel still nothing. My spark looked OK so now I am thinking carb? I had another carb sitting on the shelf so I swapped carbs still the same problem so I then pulled the cap off the distributor and cleaned up all the connections reset the points and could not pinpoint any obvious problems there. Finally I said to heck with this and was in the process of ordering new cap, points and condenser from John at Midwest, He asked what the problems I was having and then he asked when I had gotten the coil that was in the truck and I told him and he then said the coil is BAD!! He had gotten a bunch of cheap crappy coils a while back and the one in my truck was one of those, he sent me a new coil (your right it was expensive) I installed that and BANG everything was all roses once again! What a complete pain the BUTT!
 

copperline

Member
47
26
18
Location
Nashville, TN
Guys, Does anyone know the part number for the breaker plate on the M37. It's the round plate that the points and condenser sit on. It was discarded when I replaced the points for the Pertronics.

I see a few on Ebay but their part numbers don't match anything in the TM9 book
 

frank8003

In Memorial
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Ft. Lauderdale, Florida
Guys, Does anyone know the part number for the breaker plate on the M37. It's the round plate that the points and condenser sit on. It was discarded when I replaced the points for the Pertronics.

I see a few on Ebay but their part numbers don't match anything in the TM9 book
Is the dataplate still on the Auto-Lite Igniter- (distributer)?
Photo that dataplate and post the photo.
 
Last edited:

cucvmule

collector of stuff
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Crystal City Mo
copperline, a few question. Is your fuel the same fuel during this whole process? Does the fuel have ethanol added,10%. Are you using a fuel additive, Sta-bil?

I ask because what is happening sounds like either you have a distributor coil to points wire intermittent grounding to the distributor housing or the fuel is contaminated with crap.

Now the rings and valves are sticking because of the fuel additive, Sta-bil, and the degraded government mandated adulterized gasoline. NO compression to even fire off a low compression engine. The rings Are sticking from carbon buildup in the cylinder ring lands. Rather than explaining the ring sealing process for each 4 stroke process I will say the rings load. unload rotate. expand. retract all in 4 movements of the piston.

The valves are another issue but is caused by what I call varnish on the valve stems. And when cold can sieze the valves, bend pushrods or have free movement till it warms up and then becomes a slow acting glue that the valve guides are loaded and begin to slow the sealing process if the spring pressure can not overcome the glueing process caused by the gasoline additives, from the pump, your fuel station.

My personal cure is to hook up an alternative fuel source, clean fresh non methonol gasoline source, and take fuel pump feed hose and plumb into can, place new hose from pump drop into the bottom of fuel can and elevate higher than fuel pump.

I take propane torch the day before and clear the cylinders of excess fuel not the prefered method but works for me, fire protection handy, chemical, co2 and water very handy. Then onto any used plug heat and clear any gasoline saturation with the plug in plug socket without rubber, and heat until there is no more gasoline vapor present. May take 2 or three seconds two or three times to get plug insulator dried out. Check for good non cracked center electrode. Sometimes the cleaning process will break plug center electrode or separate a cracked one further.

Now onto starting , if you get started, great now have a quart of bottle of Marvel Mystery oil. It works. Use straight or mix with gasoline to thin like 2 stroke mix and either spray while engine is throttled up a little or drip into carburetor straight.

DO not be bashful you will use half a quart or more. What it will do is clean out carbon deposits on the pistons, free the rings up, remove contaminates in the ring lands. It may get some heavy valve deposits, carbon, but it will get to the valve stem varnish that are exposed in the combustion chamber and migrate up the valve stems but not likely.

Now instead of Sta-Bil I use Marvels in the fuel tank to clean fuel system from tank to combustion chamber, now I can get the valve stems clean. Using Sta-Bil does work. But I have found to many negative side effects using it. It seems bad for any cast iron made carburetors, causes the air passages to gum up or help promote rust. Turns my carb bowls green. I got tired of constantly breaking down carbs to find green crap in, on the cast iron plugging air bleeds, passages.

Looong post but I hope it helps with the great feedback posted already you will have your truck back in good health.
 
Last edited:

John Mc

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Monkton, VT
I've never experienced Stabil causing any of those problems, nor have I heard of it before. Have others seen this issue?
 
Last edited:

Bill Nutting

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Steel Soldiers Supporter
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Location
Chesterfield, Mi.
Did you remove the filter capacitor I wrote about in post #43? If my description was confusing, PM me and we can talk live on the phone. One of these days I am going to take a few pictures of this simple mod so it will be clearer. BTW, I gave up on using the Chinese coils. I built a mod that allows me to use an American made 12 volt coil. That solved my “hot coil” problem which sounds a little like this symptom but it took longer to fail. Once those crappy chrome Chinese coils get hot they shut the engine off until you let them cool down. Very frustrating. Here is a link to this mod: https://www.steelsoldiers.com/threads/m-series-coil-failures.197220/ I have been running the electronic ignition system for years without any problems. Points are good too, but I don’t think your “pointless” system is your problem. Before you buy more parts, remove that filter capacitor. It’s a free mod that will take you about an hour to do. If it isn’t the cause of your problem today, someday it will be.
 
Last edited:

copperline

Member
47
26
18
Location
Nashville, TN
I did not take out the filter capacitor. Capacitors of that age certainly go bad. I'd rather not bypass it as I do have a 2-way radio in the truck but maybe I can order a replacment. Thats a great suggestion. I wonder if that bad capacitor would cause my symptoms. I'm going to order one right now. Great suggestion.
 
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