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Hello. It's been a while! Working on a '51 1/2 ton with 216 engine. Haven't tried to start it in 2-4 years. It cranks, but there's not even a small sign of combustion, even after priming the carburetor with a couple ounces of fuel; she just cranks. I'm not sure where to begin troubleshooting. I've read a couple posts about testing the coil, but I don't know if that's the best first thing to do. I thought about pulling a spark plug and cranking it to see if there's a spark.

Can somebody please tell me the first 3 or 5 things you'd do to troubleshoot this situation? Maybe pull the distributor cap and look for a crack? Maybe replace the condenser? I'm famous for breaking something, or making it worse, in the course of trying to fix it, so I don't want to disassemble anything I don't have to.

Thanks for any help. Have a great day.

D.J.

#1 check for spark. Probably be a good idea to pull the valve cover and spray some penetrating oil on the valve stems. Don't be stingy put plenty on. May keep you from bending a push rod. If you have spark and it still won't start then run a compression check. Only 3 things to run fuel, air and fire. If it starts don't get happy with the throttle, just let it idle for awhile. Good luck.🛠

You will need to also check the fuel if you have had it sitting in the tank with the truck. Take the gas cap off and give it the smell test.

Lay a spark plug on the block somewhere, still hooked up so you can watch the gap while turning the engine over. Get rid of the antique fuel like beltfed says, small remote tank on top of the engine for testing purposes only.

Ed

Thanks everybody.

Regarding fire: I removed a spark plug and inspected. It was HEAVILY carbonized, so I cleaned it. I ran a wire from the side of the plug to the block (in lieu of Ed's suggestion to lay it on the block somewhere), turned on the key and cranked it (using a crow bar to depress the starter button so I could be under the hood). I observed NO spark. I guess I'll next test the coil, since those instructions are readily available on this site. I suspect i have a short somewhere, because this is original wiring with cloth insulation that is missing in many places. My horn will occasionally honk spontaneously when I'm tinkering under the hood, but I haven't figured that out yet.

Regarding fuel: I learned that lesson a couple times in the 15 years I've owned this truck and have drained gallons of varnishy-smelling stuff from the tank in the past. Now I keep the tank mostly empty and will pour in 0.5 - 1.0 gallon when needed. So I'm ruling out fuel, especially since I've been pouring new fuel into the carb during my attempts to start.

I welcome any suggestions on what to test next, given I observe no spark. I know I have 6.2 volts of juice to the voltage regulator and fuse block beneath it. From there, not so sure.

Thanks, gents.

Check our Tech Tips you will find one under Engines called Dead Engine Back to Life. It will give you all you could possibly want.🛠

I always check whatever is easiest to check first. and then progress to the other possible causes.
1) With the key on, check for voltage where the ignition wire attaches to the coil. If no voltage, test ignition switch/wires.
2) With the key on and the points closed, manually open the points by hand and look for a spark between the points.
3) If no spark/weak spark between the points, clean the points by pulling very fine Emory cloth through the points, followed by pulling a clean business card through the points to remove grit/debris. (Even if the points are new!)
4) If you don't have spark at the points by now, you need to check the condition of the wire between the coil and distributor. If that is good you probably need a coil.
5) Check the top of the rotor to make sure that the metal clip reaches the contact on the bottom side of the cap.
6) Check for spark at spark plug while cranking engine.

An ice pick style test light is your best friend when diagnosing ignition problems. Find a good ground, attach the wire clip to it, and TEST THE TEST LIGHT! Find a known source of voltage like the battery cable connection at the starter, for instance, and make sure the test light bulb isn't burned out. Now, start checking the primary ignition circuit. Turn the ignition switch on and check the following connections- - - -in order:

1. Coil + terminal- - - -the one coming from the ignition switch. You should get a good bright light anytime the ignition is turned on. If the light is dim or not on at all, go under the dash and check the back of the ignition switch for loose or dirty connections. If the Light is good at the coil +, go to the other terminal.

2. Light on at the distributor side of the coil- - - -this can be good or bad, depending on the position of the points. Remove the distributor cap. If the points are open, the light at the (-) coil terminal should be on. Turn the engine until the points close- - - -the light should go out. If it doesn't, check the terminal at the side of the distributor. If the light is on there with the points closed, clean or change the points. THIS IS THE MOST COMMON CAUSE OF A "NO SPARK" CONDITION- - - - -BURNED OR DIRTY POINTS! A failed condenser is a possibility, but it's pretty remote.

3. If the light flickers on and off at the coil (-) and/or the distributor side terminal as the engine is cranked, you have a good primary circuit. Now check the secondary (high voltage) circuit. Remove the coil wire from the center of the distributor cap and hold it within about 1/4" of the engine block or cylinder head while someone else steps on the starter pedal. If you're by yourself, open and close the points with something non-conducting like a popsicle stick, a plastic spoon, etc. The coil wire should fire a spark to the engine every time the points are opened. Be careful- - - -you're holding onto 20,000 volts or so. Don't get too close to the end of the wire!

4. Good spark at the coil wire- - - -check the distributor rotor to be sure it's in good condition and the correct height for the cap- - - -a short rotor and a tall cap equals no spark to the plugs. Also make sure the distributor shaft is turning- - - -a stripped timing gear will definitely cause a no start condition- - - - -no operation of the valves, distributor, or oil pump!

If the spark is getting from the coil, to the distributor, to the spark plugs, try changing to a new set of spark plugs. I have seen plugs that get a good fuel soaking from flooding that will never fire again- - - -no matter how well they're dried out or cleaned. That's also a very rare, but confirmed situation. I spent 4 hours once trying to start an Oldsmobile 350 that had been badly flooded, did all the above diagnostics, and finally got it running by changing to a new set of spark plugs!
Jerry

Thank you sharing that with us!
It verifies to me that I am not nuts (at least not for that reason). I run into that from time to time with small engines.
Carl

Thanks for the great info. 52Carl's list is what I was looking for; the Dead Engine Back to Life article (DEBTL) is a must-read; and Hotrod Lincoln's suggestions are very helpful.

Now for the update: Today I did most of the mechanical things suggested in DEBTL, and I tested for voltage at the coil. I do have voltage on both sides of the coil (+/-), and at the top where the wire to the distributor plugs in. I had the dist. cap off and inspected the cap and rotor, but I didn't inspect the points nor did I do the check where you open the points and look for spark (I'll do that tomorrow).

The really interesting thing to me, because I have started and driven this truck in the past, is that in checking for juice at the coil, I discovered that my 3-position ignition switch is ON in the center position (vertical key). I would have bet my life that in the past, she would only start with the key in position 3, to the right. But I have no voltage at the coil in that position. So I was all excited, thinking she'd start, now that I know when the key is on, but she didn't start and wouldn't even crank after about 7 seconds; starter motor just got sluggish, even though battery still read 6.2 volts.

I'll do the points thing tomorrow, now that I know which key position is ON. Or I may just go buy a set of plugs, and while they're out, I may set the timing (as described in DEBTL). It's also possible that since I thought vertical key was off, I've "let all the smoke out" of my coil, as Carl likes to say. Maybe a new one of those, too.

By the way, I do have a test light, but it's very dim at 6 volts. But hey, on is on I guess. More updates tomorrow evening, I hope.

DJ
'51 Chevrolet 3100

If it's dragging the starter down in such a short time, try removing the ground cables and straps and scuffing the surfaces they attach to. Clean the cables and replace everything.

Thanks Justhorsenround. I'll try that.

I've executed Hotrod Lincoln's protocol using a test light with ignition switch on, and here are the results.

1) At coil (+) terminal: light on. PASS
2a) At coil (-) terminal, points closed: light off. PASS
2b) At coil (-) terminal, points open: light on. PASS
2c) At distributor terminal coming from coil (-) terminal, points closed: light off. PASS
3a) At coil (-) terminal, while cranking engine: light flickers on and off. PASS >>> Primary circuit = PASS
3b) Holding distributor end of coil wire close to an unpainted area of the block while opening points with a plastic spoon: no spark. FAIL

I'll do as Justhorsenround suggests and clean the ground cables and straps and try the coil wire again.

4) Regarding the distributor cap and rotor, I would say I have a short cap (about 1.25" from bottom of cap to bottom of copper contacts), and the rotor rotates, so I assume my timing gear is not stripped.

More later. Thanks guys.

It sounds like you've got a coil failure, but just to be sure, clean the points thoroughly and try the spark test to ground again. It's also a moderate possibility the condenser has failed. For some reason, I've seen a situation where a condenser would prevent a spark from being generated, even when the points are clean and there's good primary current flow. It's almost time to start swapping parts.
Jerry

Well, there should probably be a Step 0 in Jerry's list for knuckleheads like me, and that would be, Have your battery checked. Knowing how I've neglected this battery (and the entire truck) over the last 3-ish years, including a possible change in polarity twice (once by accident, once intentionally to correct it, if I had, indeed, reversed it.....long story), I took it in for a check. It was producing a whopping 170 cranking amps. This, of course, explains the sluggish starter. So I dropped $95 at NAPA for a new one.

Brought it home, hooked it up, cleaned the points with a business card, got a spark from the coil wire, reassembled the distributor cap, and pulled a plug to see if I could observe a spark. You can imagine my surprise when the truck rumbled for about 3 seconds with the #1 plug removed, the cylinder puffing compression into my face. Definitely an "oh crap" moment.

So, I don't know if the ultimate problem was the battery, or dirty points, but it's running as we speak. Thanks everybody for your help. I've never done those kind of electrical checks before, so it was kind of fun.

You may see me pop up in other forums over the next few days, because my brakes no longer work (no pressure at the pedal, hoping it just needs fluid), and I've had a long-standing problem where she only runs when the vacuum line is disconnected from the wiper assembly. But I'll search the forums before bothering you fine people again.

Many thanks, and happy motoring!

"I love it when a plan comes together!"- - - - -I used to bug the ignition system on an engine I had in my classroom and challenge my students to find the problem. After a few months' practice, I had to get really creative to come up with a problem they couldn't find. How about creating a miss on one cylinder by substituting a piece of vacuum hose for a spark plug wire? Another sneaky trick was to use a paper punch to make a round insulator from Scotch tape to stick to one side of the points! When those kids passed one of my tune-up classes, the local auto shops were very willing to put them to work.
Jerry

That's pretty diabolical, Jerry.

One I learned when I was in the Army was putting a piece of cellophane over a fuel line fitting to prevent flow. The stuff was invisible and usually stuck to the end of the line when the fitting was disassembled if the victim got that far in troubleshooting.

Another tricky one was to run a very small sheet metal screw into the underside of a condenser- - - -it creates a dead short that simulates the points being closed all the time.
Jerry

I interviewed for a small engine repair shop job. I had to pass a troubleshooting test. It was a gas powered cut-off saw (think chainsaw motor). It wouldn't start. Checked for gas in the tank, then for spark. No spark. Pulled the cover off to get to the magneto and noticed a huge gap between it and the flywheel. Closer inspection revealed marks on the slots on the magneto where the screw heads use to ride. I called out loudly, "Sabotage!" I could hear in the distance, the saboteur (a mechanic which I soon worked right next to), bust out laughing.
I didn't have a feeler gauge so I just moved the magneto back to where the score marks lined up with the screw heads and she started on the first pull.
I never let the saboteur live that one down. He did tell me that he was impressed at how quickly I figured it out. I told him that he played dirty pool on me.

A 3X5 index card was my magneto feeler gauge for a lot of years- - - - -worked like a champ!
Jerry

Ol Red, glad you figured out your troubles.

Hot rod, I just found a sneaky ignition issue that has been giving me fits for months that you may be able to stump your class with.

Worn distributor shaft...

To figure out my situation after failing to start week after week, I finally got smart, and made/used a static timing test light after reading this article http://devestechnet.com/Home/TuneUpGuide. At TDC with the ignition on, it lit up (this is good). I backed the engine up and the timing light didn't turn off (I'm pretty sure it's not supposed to do that), so ijiggled the distributor, and the light went out. Ok... So I slowly rotated the engine to see when the points would open relative to the timing ball on the flywheel, and the light did NOT turn on even when I went well past the timing ball. Jiggled and rotated the distributor and it lit up again. Went to Start it and after messing with the distributor (technical term is jiggled) a few times she fired up.

Looking at the distributor more closely, it could be moved around about a 16th of an inch (maybe less) in any direction. After searching through the stovebolt forum, I found someone else had the same worn out distributor shaft issue. Shop manual calls for a very small runout tolerance. I'm thinking about HEI now....

This site is awesome BTW.

That wobbly distributor shaft sticks out like a polar bear in a coal pile if you're using a dwell meter instead of a feeler gauge to set the point gap. The dwell meter needle jiggles all over the place at idle, or even while cranking the engine without starting it. I had a Ford 302 engine in a F-150 with a distributor top bushing worn out so bad I had to disable the vacuum advance to get home from a 200-mile road trip because every time the vacuum came in off-idle the points would close up and stall the engine! That one was a real pain in the behind to find!
Jerry

Dang! Guess I'm in stovebolters remedial self help auto shop 101 for the blind... I'm learning slow, but making progress.

I wonder if the worn distributor thing is contributing to it falling on its face when I give it gas off idle? Your note there about the points closing when the vacuum kicks in has me wondering. It comes close to stalling but not quite.

Did you check to see if there is a spring and the mysterious disc inside of the distributor grease cup assembly? This assembly tames the wobble in the distributor shaft. If the spring is missing, you will have issues like what you have described, especially a distributor with some age on it.
Carl

I took the grease cup off the other day because I wanted to see what was in there, and nothing shot out of it. I just saw some old grease, and thought that made sense. I didn't know to look for a disk or spring. Would the spring be pushing on the cup, or is it buried in the grease?

There's a short, fairly stiff coil spring between the threaded part of the grease cup that screws into the distributor housing and the shaft. There's also a pretty thick Bakelite disc that rides against the shaft to keep the spring from wearing a groove into it. You usually have to dig a little hardened grease out to find the spring. A piece of round Teflon works well as a shaft protector if the disc is worn out or missing.
Jerry

Sounds good. I'll investigate and see if I can clean it up, re-grease and reinstall. Hopefully the spring and plate are in there.

I couldn't get it started today even with someone manning the starter while I worked the distributor. I'm about ready to buy a new shaft/body, or a 6v HEI distributor I found on Summit.

Press on- - - -you seem to be making progress. How's the storm recovery going down your way? Lots of us haven't forgotten about you, especially us veterans of Pacific typhoons!
Jerry

Yep, I will press on and get it running consistently at some point. At least I have an idea of where my troubles are. Once the distributor is figured out I'm sure something else will pop up.

We were very fortunate to have had no flooding issues during Harvey. Half day without power is nothing to complain about as it could have been much worse (single story home and no flood insurance...). Thanks for asking

Sulli, Here's the grease cup & internal parts

@photobucket

http://i669.photobucket.com/albums/..._Grease_Cup_Spring_Plug__zpszhlvfert.jpg


George
'54 3600

No good unless you have a.photobucket account.

You are allowed to post small pix here in the forums now.

Thanks for the pics George, that helped for sure. I pulled the distributor and opened up the grease cup tonight. All parts are accounted for, cap, body, spring and the disc. The disc looked like it had some life left in it so I'd didn't bother trying to get it out, and I just took out all the old grease. My plan is to pack the grease hole with grease, push the spring in there, pack it some more, load up the grease cup with grease, put on the cap (with some grease in it) and screw it all back in.

Since all the grease cup parts are there I'm wondering what is causing the wobble. I did notice that there was no o-ring on the shaft, and wondered if that could contribute to the wobble? The pics i have seen looks like the o-ring is big enough to offer some support, and thought maybe that is a wobble contributor?

A few questions:
1. Is multi use red bearing grease ok to use
2. Do I need to overfill both the body and the cup cap so that there is enough grease to make it hard to close?
3. Is the concept for greasing to squish more grease into the shaft manually by doing step 2 above (confused as to how grease moves through this thing if the cup isn't overfilled to start?)
4. What diameter and thickness o-ring do I need?
5. With the distributor out, I could only get the shaft to move up and down, not side to side, so maybe #4 is the cause?

The grease cup needs to be filled completely, so there's a solid stack of lube from the cap to the shaft. Turning the cap a fraction of a turn pushes a bit of grease around the spring and past the disc to give the shaft a little lubrication.

Where is the O ring you're referring to? The groove in the distributor housing definitely does not need a ring- - - -it's only there to keep splashed oil from the crankcase from migrating up the housing and leaking to the outside.
Jerry

In case others are having problem with photos hosted on photobucket, George's excellent photo is attached below.

I found some pics of a distributor with an o-ring on the second groove (the one above the groove with a hole in it, but when I looked at Napa and auto zone, theirs didn't have one, so maybe I found some bad info. I'm not sure now what was causing the play. The drive gear seemed to be on there solid with no visible wear and the flat tip that engages the oil pump doesn't have any visible wear.

Is there supposed to be a gasket or something at the top?

Since the bracket for the vacuum advance provides most of the ground for the distributor and the ignition system, I think a gasket would be a bad idea unless you also attach a dedicated ground wire made of high-flex wire like a voltmeter test lead, etc. that would survive the constant movement of the housing.
Jerry

Sulli,
I also had what I thought was excessive wobble on my 235 distributor, but was not sure what was normal. After I cleaned and repacked the grease fitting, the wobble went almost completely away. Also, mine had no o-ring on the shaft, and fits snug in the hole.

Lee.

Thanks Lee. I re-did the grease cup, helped some with the wobble, but still no fire. Finally put a multi meter on the condenser just because i hadn't done that yet and it seemed like it wanted to be 1.6 with my multi meter set on ohms and 200. Checked the manual, and it says that the condenser should be between 18 and 23 microfarads, and guessed that I was looking at 16 which was below spec, so I ran out and bought a condenser. The darn thing fired right up! Wish I had checked that earlier....

I had a list of to-do's if it ever fired up again, so I got to work. I had put coolant flush in there beforehand, so I let the thing run, and found that it didn't get over 180 idling for 30 minutes, oil pressure was around 15 and would rise with throttle, it never fell on its face when I hit the gas off idle, the vacuum advance needs to be replaced, have an oil leak at the fuel pump, and the clutch chattered a little (maybe it's just because it sat for 19 years, or needs adjustment?). I shot some MMO in the carburetor and couldn't get the thing to smoke in that whole 30 minute session.

Drained the oil and added fresh. Drained the coolant, and am still waiting for it to cool down enough to reverse flush it, but nothing gross came out after all that running, so I'm not too worried about it yet.

Now for the best part. I did a compression test (the right way, with a warm engine, plugs out and throttle mashed) and I have something that is worth driving for a while! It's not perfect, but it went from a cold reading of 55, 61, 70, 70, 75, 75 to an acceptable 100, 100, 110, 100, 95, 105!! The manual calls for 130, but I think I can live with an average of 101.

Thanks for everyone's help. I think the "diagnose, then correct" advice was the best. I was going to throw a whole new distributor plugs and wires at this thing to make it work, and it came down to diagnosing the bad part (condenser) and getting the timing right. I even used the old spark plugs after buying a new set...