Starter circuit problem

[pycoed]

I just read a little about starter repair. It said when tapping on the starter makes it work, the problem is usually the starter. It said one of the most common starter problems is the copper contacts need to be replaced. Looks easy, just have to find the parts. A rebuilt starter for this tractor is $400, so I will soon be adding starter rebuilder to my resume.

I've just been through all this twice! First time ( old tractor was new to me -I'd had it one day) the starter switch didn't disengage the starter & the result was a burnt out set of field coils. Took the starter to repair shop(those field coil pole pieces are an absolute B***** to remove if you haven't got the pole screwdriver) & got a rebuilt starter with new solenoid, brushes, overrun clutch & fields plus polished armature. Would hardly start the old girl, so I put my diesel car battery on it: same result, changed all the battery leads: same result, checked everything with the meter, everything checked OK but the starter was still sluggish. Couldn't be the starter that was new?
Sometimes it wouldn't start at all, others it would JUST start it. Took starter off & back to the shop - they found one brush stuck up, so had to repolish the commutator & were very red-faced about it!
4 working brushes & the original battery now spins it up first time every time! Check your brushes - if the starter was as awkward as mine to get off, you can usually just remove the end cover in situ to inspect/renew them. Other thing it might be is bad connection on the solenoid power contacts inside. Solenoids are cheap enough, may be able to change that without removing the starter too, though if it comes off easy, all this is a piece of cake on the bench

 

[SPYDERLK]

Starter trouble does not fit the original symptoms you reported. Your battery tho, at 12.2V quiescent, was iffy. Have you checked the charging system. Stand back and assess well. It will save you money.
larry

Dont rebuild anything until you know what is wrong. It may be that I misunderstood your description of the symptoms, but as interpreted it cannot be anything but a cable. With a slight mental leap in imagining where you measured, it could be the solenoid. Unless Murphy has struck you multiply with a sledge, the starter itself is not involved because that would have required several problems to manifest simultaneously to match the described symptoms.
larry

 

[patrick_g]

Larry, Like Sherlock Holmes, I am not a big believer in coincidence but when all the impossible choices have been eliminated then whatever is left, however improbable, is the truth.

Given time there can be destructive interactivity in the battery related components. An internally corroded cable from acid wicking into it can interfere with cranking and or charging. If cranking is not optimal then the overall load on the batt increases as well as that on the alternator. I have had a marginal alternator eventually take out a batt and vice versa. Before I got over my strong (near maniacal) desire to find the single culprit, I would try to only change THE SINGLE BAD PART. I was overcome by a gust of reality with a lifetime alternator that I had to change out 3-4 times in 18 months along with the batteries it ruined (two at a time as it was a diesel pickup.) I had a similar problem with my Dakota when the wife had to have a new alternator installed when she made a round trip to Iowa and I had to change out the starter.

Luckily, most of the time troubles come one at a time but every once in a while two or three components (especially if there is an intermittent involved) can lead you on a merry chase.

I'm anxious to get the final SITREP and see what all needed to be replaced and what if anything got replaced but wasn't needed.

Pat

 

[Laneman950]

Still having trouble after starter repair. I cleaned the solenoid plunger disc and replaced one contact for $5. Other contact and plunger just needed light cleaning. I kind of doubted this was the problem, the starter parts looked pretty good. Here's what I've done so far. When I was only getting 4v when the key was on, I replaced the battery and the positive cable, cleaned all contacts. Neg cable looks perfect, tests good with ohmmeter. What I haven't done is replace the neg cable (which looks and tests good), the ignition switch, the starter brushes. It's time to get the meter out once again and try to figure it out. Last meter test showed full voltage at starter end of cable when key turned, so one problem is gone. Cables have almost no resistance, no corrosion, pos cable is new. Any advice is welcomed.

 

[FULLPULL]

I ask what kind of tractor and close to the year model?

 

[RickB]

Kinda depends on where you attach the ground lead of the meter. If you use the neg battery post, you are not testing any of the ground path. Grounding the meter on the starter chassis includes the entire ground path in your voltage test. My favorite battery and cable tester is a cheap 100 amp hand held load tester. I test each cable and connection and the complete grounding path according to where I connect it. Much more accurate than interpreting voltage readings.

 

[FULLPULL]

If your tractor has a generator then it could need to polarized then it would charge again . Just a thought. Some older tractors had a positive ground also around 1950 some of us would know if you tell us the tractor model.Thats why i ask.

 

[civesnedfield]

Still having trouble after starter repair. I cleaned the solenoid plunger disc and replaced one contact for $5. Other contact and plunger just needed light cleaning. I kind of doubted this was the problem, the starter parts looked pretty good. Here's what I've done so far. When I was only getting 4v when the key was on, I replaced the battery and the positive cable, cleaned all contacts. Neg cable looks perfect, tests good with ohmmeter. What I haven't done is replace the neg cable (which looks and tests good), the ignition switch, the starter brushes. It's time to get the meter out once again and try to figure it out. Last meter test showed full voltage at starter end of cable when key turned, so one problem is gone. Cables have almost no resistance, no corrosion, pos cable is new. Any advice is welcomed.

You are off to a good start rebuilding the starter but you stopped short. Take off the back cover off and take a good look at the brushes. Chances are they are worn along with the communtator on the armature. My dad rebuilds for a living and does not believe in messing around with just one thing. If ya got the starter off the tractor don't mess around do a complete rebuild.

 

[cpdtwo]

I have the same trouble as posted. replaved the starter and it does not turn over the motor past a compression stroke, it just stops. had 2nd starter sent out and no differece. both where staters that where replacement one for my model. now I'm waiting for the correct starter, or so I hope. I had replaced the cables and battary and with a jump and new battery it stil only turns over and starts once in a while. Could the ingnion switch be the problem by sticking. I do not think it would be the charging system as with the jump there should have been more than enough amps to turn over the starter. as there in nothjing else but the switch or starter what could it be?

 

[SPYDERLK]

Still having trouble after starter repair. I cleaned the solenoid plunger disc and replaced one contact for $5. Other contact and plunger just needed light cleaning. I kind of doubted this was the problem, the starter parts looked pretty good. Here's what I've done so far. When I was only getting 4v when the key was on, I replaced the battery and the positive cable, cleaned all contacts. Neg cable looks perfect, tests good with ohmmeter. What I haven't done is replace the neg cable (which looks and tests good), the ignition switch, the starter brushes. It's time to get the meter out once again and try to figure it out. Last meter test showed full voltage at starter end of cable when key turned, so one problem is gone. Cables have almost no resistance, no corrosion, pos cable is new. Any advice is welcomed.

Does the solenoid click everytime you turn the key? The solenoid is an electromagnetically actuated switch. The batt + cable connects to one side of the solenoid and the starter itself is isolated from this connection when the solenoid is not closed. That click is the solenoid closing. This should be connecting the 12V you are measuring, at the end of the + cable .. the input of the solenoid, to the other side of the solenoid in order to energize the starter. You should be able to see the solenoid output to the starter. It may be another large terminal .. near identical to the one the + cable is bolted to--a picture would help. We want to know 12V is getting to this output terminal. There should also be a 3rd terminal on the solenoid, smaller than the others. This is the one you switch power to with your ignition switch. When +12V is connected here the click happens and the power formerly isolated at the input is connected across to the output. The starter should run if the +12V is making it to the output. Find this output point. Measure from this point to the body of the starter. The meter should read 0v before the click, and about 11V with engine cranking after the click. If it reads 12V and the starter does not run it is probably your brushes hanging up [or maybe worn out if its an old tractor]. If the output point continues to read zero or jumps to just afew volts it is the solenoid not closing properly, or its your ground lead. To test the solenoid, put your meter across the 2 big terminals on it and turn the key. This indication should be 12 before the click and very close to 0 after if the solenoid is closing ok. Be sure to not use ohm setting on an energized circuit. Use V only
larry

 

[Laneman950]

I think I may have found the problem. I did a continuity test on the wire going from the ignition key to the solenoid. I had my wife move the wire around and I was getting intermittent continuity. I repositioned the wire temporarily and it started ten times in a row even while hot. It's never passed this test yet. I think the ignition wire has a break or loose crimp in the copper near the terminal. I'll crimp on a new terminal and post the results.

 

[john_bud]

I think I may have found the problem. I did a continuity test on the wire going from the ignition key to the solenoid. I had my wife move the wire around and I was getting intermittent continuity. I repositioned the wire temporarily and it started ten times in a row even while hot. It's never passed this test yet. I think the ignition wire has a break or loose crimp in the copper near the terminal. I'll crimp on a new terminal and post the results.

Spend the 1/4 cent and solder the terminal on. Then paint on the liquid electrical tape and slide a shrink wrap tube over all that. Wait an hour or two and then shrink it with a match or heat gun.


I HATE crimp connections as they uncrimp at the worst times.


jb

 

[gemini5362]

I might differ in the above advice just one little bit. take off the terminal. Slide some heat shrink tubing over the wire and get it as far as you can from the terminal end. Put the terminal end back on solder it in place then slide the heat shrink back over the terminal and use a hair dryer or something like that to heat the heat shrink.

 

[Laneman950]

Thank you, soldering didn't even occur to me. I think that is a good idea.

 

[patrick_g]

Still having trouble after starter repair. What I haven't done is replace the neg cable (which looks and tests good), the ignition switch, the starter brushes. Cables have almost no resistance, no corrosion, pos cable is new. Any advice is welcomed.

A couple feet of number 28 or 30 gauge wire will test on your ohm meter and show essentially zero resistance. OF course it will burn up in a fraction of a heartbeat if you put it in series with your starter current. Testing battery cables to see if they are good for high currents, double or triple digit amps with a standard ohm meter is: 1. almost a waste of time and 2. misleading.

Say for example that your peak cranking draw is 100 amps. Lets say your cable has 0.1 ohms. Ohm's law (E=IR) shows us that a cable passing 100 Amps and having a resistance of 0.1 Ohms drops 10 volts. Taking a very simplified look at the situation... the 2 volts left over won't crank your starter very well.

OK lets say you would have noticed 0.1 ohm on your meter.. Would you have been alarmed (assuming you would even notice) if the cable measured 0.01 Ohms? At 0.01 ohms you would still loose a full volt in the cable. Many folks don't have meters that accuratly measure resistance in the area of a small fraction of an Ohm.

A better way to measure things for trouble shooting purposes is under load, passing a realistic current (not the microamps of the ohm meter AKA Ohm Eater.)

If you measure the DC volts between the battery post (not terminal) and the starter terminal (the threaded screw, not the terminal on the cable) and then try to crank you get an idea of the actual loss in the cables and connectors. If the voltage is more than a fraction of a volt then something is providing too much resistance. The resistance can be in the battery clamp to battery post contact, the terminal to wire crimps (if any), corroded cable, or whatever. If you are not delivering nearly full voltage to the starter it will not crank correctly. Now please note that "full voltage" is NOT 12.6, 14.2, or whatever. Under the starting load the battery voltage sags considerably. You need to measure the battery voltage under load and see what percentage of that makes it to the starter.

Digression time.. a brief walk down memory lane... Back in the olden days some 12 volt cars had ballast resistors in series with the primary side of the ignition coil which reduced the voltage to the coil to about 10 volts. When cranking the starter, the ignition switch shorted out the ballast resistor to give the coil FULL VOLTAGE. Of course while cranking full voltage was about 10 volts. When you released the key it went back from the start position to the run position and the ballast resistor was in circuit again preventing the 10 volt coil from burning out running continuously on 14.2 volts.

IT is a well established fact that the battery voltage needs to be measured under load. If crankiing and measureing at the same time is a hassle (it often is) or you are concerned that al this crankinig is not good for the starter (it isn't) then for maybe $25 at Harborr Freight you can buy a battery load tester which can be substituted for the starter as a battery load while making tests. Some guys use and advocate the use of the headlights on high beam as a load test but there are shortcomings to that: 1. the lights aren't wired to the starter cable and doing so is a pain, the load choices when using the lights are just two (high or low beams) and neither is anywhere near the load of a starter or the load tester.

Readers Digest version: Resistance readings may lead the unwary astray. Use voltage readings under an appreciable load to make determinations about the various components' ability to carry current to the starter. If the T-shooting takes a while use a battery charger on the battery to keep it up.

If you want details on any specific issue or for any other reason you can PM me.

Pat

 

[SPYDERLK]

Much of what Pat says is absolutely correct. He is dead on regarding the need to use a voltmeter to determine the potential across a current carrying wire to find out how efficiently it is conducting. Since it must push current thru the wire and measure it accurately, an ohmeter on its most sensitive scales has grave problems with contact quality to the wire being tested. A fraction of an ohm corruption of the contact made by your test leads comes back as that much error in your reading. A sensitve voltmeter draws a much smaller current than that used by the Ohmeter. This is due to the fact that the Vmeter has several megohms input resistance. The small but inconsistant contact resistance of your leads to the circuit when using a Vmeter makes very little difference when grouped in proportion to the millions of the meter.

With a sensitive Vmeter the idea of appreciable test current can be reduced to values that may seem ridiculously low, without losing real world accuracy in the tractor testing realm. Literally, the lights are plenty of draw, and are ideal if power for them comes from a connection made at the solenoid input terminal. With a low drain, say 5 Amps, from this terminal to ground you can leisurely go about your diagnostics with a Vmeter. I have a superbly cheap digital VOM I got from Horrible Fate for $2.99 as I recall. It will discriminate down to 0.1mV. So you turn on your 5A load to check your batt cables. Touch your sharp pointed probes to each end of a cable - not the terminal lugs - jam the points into the cable. Perhaps you get a 1.0mV reading. That cable will conduct 5000A with a loss of just 1V --a very good cable for a dozer even. Next you check from the battery post to solenoid post... or the frame, depending which cable youre doing. These points show a difference in potential of 100mV. TROUBLE. 50A will lose you a Volt. Check from batt post to clamp... 0.4mV -good. Clamp to adjacent cable wire... 20mV -to be fixed. Cable wire to terminal lug... 5mV -wish it was better. Terminal lug to frame/ or solenoid post... 73.6mV -the killer. Took a minute or two. Buy a digital meter. Your starter will thank you.
larry

 

[patrick_g]

Larry, I bow to your superior breadth of experience. I do not know from personal experience what proportion of things you might want to test in a battery/starting/charging/and-everything-else-electrical-on-a-vehicle can be tested by turning the lights on and off. I have had some experience with situations that weren't ferreted out with the draw of the lights but succumbed to a variable load tester when the load was cranked up.

I have been unfortunate to have had some weird problems that may not be at all representative of typical failures experienced by most folks. You know how it goes... behind my back whether I know it or not mother nature is laughing at me along with Murphy!

Like nature abhors a vacuum, I feel that way or worse toward intermittents.

Soldering automotive wiring connections that are subject to weather or vibration is a good idea. properly crimped connections (certicrimp tool or similar) are good enough for aircraft work in a vibration environment but not everyone REALY knows how to crimp properly and the cheap Chinese terminals so common these days aren't the best (nor are the cheap crimping tools.) Soldering seems to be a dying art as well. not many folks really know how to do it right. I have seen lots of garbage joints that were either cold joints insulated by barely melted flux or overheated joints that embrittle the copper wire so it breaks much much easier.

Assuming you get a good joint, then protecting it from the elements is less important than protecting a crimped joint from the elements but is still a good idea. If you are really **** about protection there is heat shrink that oozes a sealer when heated and makes for a waterproof hermetic seal of the protected joint. You can DIY with silicone rubber. Don't heat the shrink tubing and then put on the silicone rubber afterward. Instead squeeze the silicone rubber into the space between the tubing (before it is shrunk) and the joint to be protected. Then shrink it.

If you buy a trailer or have after market accessories installed such as a trailer light/brake plug-in or such you can be assured the odds are that everything was wired using insulation displacement squeeze connectors that will corrode and fail and can produce intermittent brake and lights on your trailer or malfunctions of the arftermarket equipment. It would head off future problems if you redid their chintzy connections and soldered or used proper crimp connections and water proofed them.

Pat