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1947 RTU No Spark

J

JKC

Member
Purchased a 1947 RTU about 12 years ago. Converted it from the 12-volt system previous owner had made, back to a 6-volt system. The tractor
is NOT exposed to the elements and is always inside a heated shop. The tractor will not spark or ignite. I have tried various things over
the years, without success. This tractor will NOT spark. Here is a list of what I have done:

New battery & battery cables
New correct custom-made wiring harness
Rebuilt carburetor (tractor ran good after that for a few months, then without any changes, simply would not start again & hasn't since)
New spark plugs, properly gapped
New spark plug and distributor wires
New coil
New distributor cap
New condenser
New dust cap
Cleaned & re-gapped points
Cleaned all electrical connections

There is electrical power to the starter, the coil and the distributor. The tractor will crank all day long, but will not even attempt to
spark or ignite. Pretty frustrating.

I am looking for any and all advise or suggestions. I look forward to hearing back from folks.

Thank you in advance!

JKC
 
Assuming you have a distributor. 1. file the points and check the gap. 2. Is it possible the distributor is grounding out somewhere? Put a continuity light on the lead from the coil, it should flash as she is turning over. 3. Rotor button issue (rare but can happen) These are 3 simple quick check. Get back to us if no luck.
 
I transported a nonrunning tractor to a mechanic for someone once with a similar problem. Turned out someone put the wrong screw in the points IIRC shorting them out.(I think the screw was too long) Someone here already suggested it but just an example of how it can happen.
 
I'd verify that the points are clean and closing if it has a distributor. If it has a magneto, is the impulse working?
 
If it's timed right and rotor turns with engine I would say check the condenser. It's not uncommon to see a bad new condenser.
 
A couple of clarifications: This tractor does have a distributor, rather than a mag. Also, I guess I forgot to mention that I did indeed install a new set of points and properly gapped them.

Based on the suggestions I have received so far, it sounds like I should focus my attention on the distributor? I will check for the possibility of it shorting out due to some improper contact.

Also, even though the tractor seemed to run OK for several weeks after I converted it from 12 back to 6 volts, is it possible I may have missed something during the conversion?

I appreciate ANY additional suggestions/ideas others may have concerning this problem, and thank you to those who have responded so far!

JKC
 
SMS, Sorry for my ignorance here, but what does "IIRC" stand for in your reply, or was this just an inadvertent typo error?

JKC
 
Since it did run for a while after the conversion, but does not now run, is it possible the coil is wired backwards and burned out? I did this once myself. If it is a positive ground, the wire to the distributor needs to be wired to the positive terminal on the coil. Negative ground, the wire to the distributor needs to be connected to the negative terminal of coil. If wired wrong, the tractor will run until coil fails.
 
JKC also check where the wire goes through the distributor body, they can short here. A condencer can be a problem also. Pull cap and see if rotor turns when you crank engine. When I do this I would start from the starter switch and work my way out. Got to rule out stuff like failed ignition switch rusty connection etc.
 
With the ignition switch turned off pull the distributor cap off the rotor and dust cover so you can see the points. With the point closed take a piece of wire and hook it to the non ground side of the battery. Now touch it to the coil the side that does not go to the distributor. When you touch it to the small coil wire place you should get a small spark. If no spark then the points need to be cleaned. If you get a spark turn the engine till the points are open and do the spark test again. If you get a spark when the points are open you have a short so look for a wire like the condenser wire shorted to the case of the distributor or the insulator going threw the side of the distributor maybe shorted
 
"is it possible the coil is wired backwards and burned out?" You are right in how to wire the coil. Wiring it backwards will not cause it to burn out. It will reverse the direction the spark plug fires which will cause slightly weaker spark and on an MM will likely cause harder starting when engine is cold. Not necessarily in winter but also first attempt to start on warm summer morning.
 
Waste of time cleaning points. Material used is not meant to be filed. Mag points yes. Points made today terrible, especially Blue Streak. Had new ones out of box not work. Check resistance with ohmmeter is best.
 
Sorry that abbreviation is used pretty often on this site and I don't think about it. If I Remember Correctly IIRC.
 
WRONG I have done so at least 1000 times in the last 30 year and have points in tractors that are almost that old. Clean them and go for a year or more then clean them again. I have tractor that have not had new points installed for more then 20 year and a good cleaning and there good for long time
 
I wanted to thank you all for responding to my question. I will not get to try these suggestions until Saturday, but wanted to express my thanks. After I get some time in the shop this weekend, I will let you know what works (hopefully)!

Any additional suggestions are still very much welcome!

JKC
 
SMS, Thank you for clarifying. I haven't been on the forum for quite some time, so was not aware.


Thanks!
 
Jocco, Thank you for clarifying. I haven't been on the forum for quite some time, so was not aware.

Thanks!
 
Well that number if just that a number could be longer. As for E.T. that started in 1974 you do the math
 
To Old and Molinegb: Forgive me for sticking my nose in this debate. But I know where both of you are coming from. I have been cleaning points for over 75 years. And will continue to do so. However the companies that make points claim that they should never be filed because it removes the contact coating that is on the surface of the points. One thing for sure your hands must be clean when you handle and install points. Wipe off the contacts with a good clean shop rag. Dirty, greasy points right off the bat will cause them to arc (if they do make any contact) and start to damage the contact surface.
Soooo owner be the judge how you want to service your equipment.
MMDEL
 
MMDEL, Would you happen to have any additional suggestions of what I could check, other than what has already been posted? I respect your
opinion and decades of experience, so happy to hear any of your ideas!

Thanks!

JKC
 
Since you said it had been on 12v, is it possible that there is still a ballast resistor in the hot wire from the switch to the coil? You need to eliminate it if there is.

If you connect your test light to the terminal where the wire from the coil goes into the distribuitor housing and crank the engine over, does it blink? If it does the points are making/breaking at least somewhat.

With the cap off, switch on and points closed, does the coil make a spark jump from the coil wire coming out of the coil when you open the points? Moving the points with your finger should not shock you, You will probably see sparks, but you might want to use a test plug in the coil wire rather than hold it. If not try different points, different condenser, or an other known-to-be good coil. Its not unheard of to get a bad part now and then.

IF you get a good spark from your coil at the coil wire, then you need to try a known-good distribuitor cap and/or rotor button.

Another place the spark can jump to ground on a MM is through the metal wire looms that support the plug wires. So make sure you plug wires have very good insulation there.

Lastly, I have seen several cases where the spark plugs get a grey glaze on the insulator and the tractor suddenly comes to life if the spark plugs are changed. That glaze is due to burning old fuel, but if you want to blame it on the mean old spark plugs, that is your opinion.
 
Thank You very much for the compliment.
TKR came up with a good thought. Do you know if the coil is a 6V or 12V? In any event if there is a resistor in the circuit ahead of the coil remove it. (I have been running a 6V coil with 12V on a Hyster fork lift for 40 years, not recommended) The simplest way to check out an ignition system is the way I started out with my father and uncle on the farm who were great machine men. (Did custom corn shelling for 50 years dad owned the neighborhood threshing machine, and did custom combing) Also this is the way they taught us in the Army at the Truck mechanic course I was fortunate to be placed in. Very simple, because when you are in a war zone you don't have all the bells and whistles for tools and testers.
Take off the cap and dust cover. with the engine turned so the points are open take a screw driver (and scratch to ground) or test light see if you have current (juice, spark) at terminal on coil from switch, if not check switch and wiring back to the battery. If so check terminal on the terminal to the distributor, then post on dist., then the insulated half of the points. Then remove the coil wire from the center of the dist. cap and hold the end 1/8 " from the engine block. With the screw driver bridge the gap between the open points, as you make and break this gap with the screw driver you should get spark at the coil wire to block. If not you may have a bad condenser, then rotate the engine to close the points. Now take your finger to open and close the points you should get spark at the coil wire. If not clean the points. On bad points it may take 3 or 4 cleanings. If this all works then place the rotor in place on the shaft. Hold coil wire with a gap above the contact on the rotor, break the points with finger if you get a spark the rotor is bad and leaking to the shaft. Inspect the inside of the cap look for cracks and carbon traces, clean contact lugs. A good homemade tool to clean the lugs is to take an old screw driver, sharpen the blade like a chisel then heat with a torch and bend 1/4" of the end 90 degrees. You can hold the cap with one hand and scrape the lugs with your new tool.
Any other questions, I usually check this site each morning when I am at the shop.
MMDEL
 
By the way I don't remember from your earlier posts, do you have solid wire, wires to the spark plugs. Carbon silicon wires are a NO NO for points and condenser systems.
MMDEL














c
 
SWMoline if you are taking notes along the way you can be my co writer. I'll even put your picture in the book.
MMDEL
 
If you have been doing that for 75 plus year that would mean you would have to be in your upper 80 or low 90s
 
This has to be a record for a chat due to no spark. You may find the problem cured by holding on to a plug wire with your bare hand while cranking the engine over. LOL. Don't do that, but it would figure.
 
Curt: That is the way I always check for spark! That's the very first thing I do when an engine won't start. grab a hold of the plug terminal to feel if there is any spark. A lot of engines nowadays have boots over the plugs so you have to pull the wire and stick my pliers handle in the boot to grab onto.
MMDEL
 
E.T. Computer when in the navy. My older brother and nephew are/where nukes. Nephew is in A or B school at Goose creek in SC.
 
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