Could use some help diagnosing a problem on a 129

[MARK (LI)]

I went to start it (129) today, to find that the belt from starter generator had come off. I knew there was a rattling from the front of the engine, but I thought that it was the PTO clutch. Since I only use this tractor for its loader, I was not worried about it, but it turned out that the pulley from the starter was what was loose. So I pulled off the hood and got the clutch off and it was getting dark. I tightened up the pulley, although I have to get back to that, and get a new woodruff key for it. Since I do not use the PTO, I left it off and tightened up the belt and tried to start it. This thing always starts at the touch of the key, it would not start. I put a spark tester on it, no spark. There was 1 ground wire to the chassis where the grill bolts on and another at the front pivot bolt for the starter generator. I got them on tight as can be, but the engine would not even turn over if that were the problem. So, it has to be either the coil, condenser, or points....or could it be something else? Are there any methods of testing any of this stuff?

[R Bedell]

but the engine would not even turn over

The coil, points, and condenser have NOTHING to do with the engine cranking over. The Starter Solenoid is what controls that. You either have (A) Bad contacts within the solenoid, (B) an open solenoid coil, or (C) no power going to the solenoid coil.

[MARK (LI)]

Originally Posted by R Bedell

The coil, points, and condenser have NOTHING to do with the engine cranking over. The Starter Solenoid is what controls that. You either have (A) Bad contacts within the solenoid, (B) an open solenoid coil, or (C) no power going to the solenoid coil.

Thank you for responding, but I think you misunderstood my problem....what you have quoted me is taken out of contest.....I said that "but the engine would not even turn over IF THAT WERE THE PROBLEM"...referring to the possibility of loose or absent ground....there is no solenoid on this...it is a starter generator and that works fine...I have no spark ...so that is why I am inquiring about the ignition components..thank you anyway...mark

[sawdustdad]

There is a solenoid-it's under the dash, it's just a big relay, really.

We assume you removed the plug and grounded the threaded portion to the engine (on a bolt head for example) and watched for spark while cranking.

Check for 12v at the + terminal of the coil with the key turned "on"

check coil for continuity (should have continuity).

Check coil for resistance--2 to 6 ohms. If zero, it's a bad coil.

remove points cover and clean the points. Run a dollar bill between them, or a piece of fine sandpaper. Check again for spark.

Check to see if the plug sparks from the threads to the ground point--it should not. replace plug if it does.

Do these things and report back. I'm betting it's just dirty points.

[MARK (LI)]

I have a good spark tester...and it was getting dark so there was good contrast...I am thinking points also...just got too dark to try that...kind of strange how it "just happened"...I had it running an hour or 2 before...with that relay under the dash that you mention...that does not seem as though it could effect spark...could it?...also to check for resistance and continuity through the coil...should I disconnect the wires, or is it ok to do it with them connected?...the other info you gave me I appreciate and plan to keep it on hand for now and future use...it is exactly the kind of info I was looking for...thank you ..Mark

[Billy-O]

If by any coincidence... Any chance you leave the key on and boiled the coil about around the time you started working on the slipped belt?

[MARK (LI)]

No...that engine never just died at idle like some do...I have to turn the key off to shut it down......so I never would leave it on....and I had one tractor recently that for some reason, I would leave that key on ...but would realize it the next time I went to start it and would kick myself in the butt....thank you for the interest, and please let me know if you think of anything else..I do appreciate it.....Mark

[cooperino]

I think the confusion comes with the lingo used.

When someone says "engine wont turn over" we assume that the engine literally wont turn or no crank leading us to think towards starter issue. When the engine will turn but wont start we would say not firing or cranks but wont start. So your engine is turning and you've tested for spark and there is no spark present. The first test would be to check if voltage is present at coil with key on.

[Mike McKown]

Originally Posted by MARK (LI)

So, it has to be either the coil, condenser, or points....or could it be something else? Are there any methods of testing any of this stuff?

Put a test light on the plus coil post and check for voltage with the key on. If that's okay, move the test light to the negative side and crank the engine. The light should flash off, on, off, on. Not dim, bright dim.

If you get no flash on the second test, your points are not making/breaking the circuit. In other words, burnt or dirty. If you get a flashing light but still no spark, I'd suspect the condenser.

[MARK (LI)]

Originally Posted by sawdustdad

There is a solenoid-it's under the dash, it's just a big relay, really.

We assume you removed the plug and grounded the threaded portion to the engine (on a bolt head for example) and watched for spark while cranking.

Check for 12v at the + terminal of the coil with the key turned "on"

check coil for continuity (should have continuity).

Check coil for resistance--2 to 6 ohms. If zero, it's a bad coil.

remove points cover and clean the points. Run a dollar bill between them, or a piece of fine sandpaper. Check again for spark.


Check to see if the plug sparks from the threads to the ground point--it should not. replace plug if it does.

Do these things and report back. I'm betting it's just dirty points.

Not getting any voltage to the + side of coil....no arc at the points...continuity and resistance looks ok