How to test if starter bad

[still learn'n]

Is there a way to test if the starter is bad when it is still on the machine? The case is on a RM500 with C15 motor it wudnt start cuz the batteries appeared to be low voltage! I jumped it and got it started and then it happened again so replace batteries! then the volts was still getn jerked out of the batteries sumhow! yesterday went to get it and it wudnt start hooked a grader up to it and left it on for 20-30 min and still wudnt the jumper cable were getn hot like it was pulln lots of volts! could the starter have short in it that wud be pulln the batt down? btw it was in the 20's yesterday so was cold to! Thanks Jerry

 

[Delmer]

could the starter have short in it that wud be pulln the batt down?

Yes, the starter can go bad and draw too much power and not turn fast enough. I once started a nice ladies pickup on fire at a gas pump trying to jump a starter that was doing that, in that case the cables would actually tense up like hydraulic lines when she tried the starter, should have been a warning sign. Another sign is when the starter cranks slow like the batteries and engine are cold, even after the engine is warmed up and the batteries are charged.

I don't know of a way to test the starter except for a DC clamp meter and some idea of what the amp draw should be, but you can eliminate the other possibilities, bad batteries, drag on the engine, bad connections/cables. Did you check the battery voltage before trying to start the engine to see if they had been drained down overnight? Sure sounds like it's getting enough amps, but you could check for any connection getting hotter than the cables after cranking. Not sure how you'd check for drag other than to try to turn it over by hand?

 

[Old Doug]

Jumpers are no replasement for good battiers. If you remove the cables and charge them for as long as it takes to get them in good shap then try and see how it turns over. Did it start last winter? Does it have some way to warm it up?

 

[d4dozer]

I had a similar problem once and found that the connection between the battery lead and battery connector was poor. I went through putting on a new battery, jumping it, noticed the cables were hot and so one. When I fixed the connection between the cable and the battery connector all was fine and has been since! Good luck with your problem

 

[richard.bessey]

I had a similar problem on my little pickup. Get a volt meter, put one lead on the battery lead, the other on the lead of the battery. Press the starter button (May need someone else do this for you) and watch the voltage accross the lead. If memory serves me right, you should see no more then 2 volts. If you see less then 2 volts, your wiring is good. May want to do this again on the ground side.
If that tests out good, you either got a dead battery or bad starter. Mine had a bushing inside the starter go bad, still worked but pulled too many amps and couldn't turn over the motor anymore.

 

[Cmark]

Check the voltage at the starter motor whilst cranking. If you're getting around 19v or above and the starter's getting hot, it's a fair bet that it's no good,

BUT with a caveat....

bearing in mind it's an RM500, there's a lot of stuff going on after the crankshaft with many possibilities for a parasitic load to drag the whole show down.

 

[rivroshaun]

I had some trouble understanding whay exactly your complaint might be, so please excuse me if I sound like if I'm pointing out to another problem. So I will try to go sentence by sentence an answer you questions.

1. Yes you can, either with a DVOM (digital volt meter) or even better a Power Probe.

2. If you got the machine started then I doubt the starter is bad.

3. I'm not sure what you mean by "the volts was still getn jerked out of the batteries sumhow!" But from what I gather you are saying the batterie is draining. Is this happeining while the engine is running or when the engine is off? From my experience starters do not drain the battery whatsoever in either the engine running or engine off conditions. The only way for the starter to do this if it ran all the time, and trust me if that was the case you would hear the starter running, and after about 3 minuetes never be able to start the machine again (The starter would cook itself).

4. Now before we go any further since you could not get it to start with a motor grader, Was this a crank, no start condition? Or a no crank, no start? From what I read from your discreption I am going to assume that it's a no start, no crank. From this point on I need to no what you are hearing. Whan do you hear when trying to start the machine? Do you here the starter engaing? do you here a whinning soud? This will tell me if you actaully do have a starter problem?

My suggestion to you is to check all your cables and look for any corrosion and or loose connections first. Then start using a DVOM and crank the engine while looking for voltage drops. Look for anything more than 2-3 volts. This will tell you witch circuit has the problem. You also could have a parasitic drain somewhere if the battery is dying overnight.

I know this didn't solve your problem but your questions lead me to more questions. In other words I just need more info.

Your starter could be bad. I don't know. With your description if your starter did go bad, I think it's because you have something going wrong that made it go bad. Or simply something is working your started really hard and it coooked.

 

[still learn'n]

For starters we got this machine last spring so I don't know how its starts in the winter time! It has ben starting fine all summer and then it wouldn't start when I went to go do some work on it and so I jumped it off dozer and then left it run for a while then I shut if off left it for a few minutes and started right up! Then 3-4 days later it wouldn't start again so went and jumped it and checked voltage and said it was low and had been having lots of battery problems with other machines so just changed the batteries. Then I went and installed a new valve on it and it wouldn't start again and during this time it wasn't that cold so I charged it with my welder and got it going and I left it run for a while again and then I shut off the cut off switch cant remember what call right now! we have problems with gps drawing juice on our dozer so we cut the switch all the time otherwise it can be dead in the morn so I figured that if it was something pulling the volts out of the batteries it would stop that but to no avail! I went to haul it back to the shop cuz we were done with it at the job and it wouldn't start so went and got a grader to jump it and it would slowly turn over for bout 5-10 sec and then just click and so tried that how many times thot maybe it would charge up enough but that didn't work either and then it was getting dark and I didn't have my service truck to have tools since I was in truck and lowboy! so was wanting to have some suggestions to know what to check when I go to check it out! Thanks for the replies more question will try to answer them! Jerry

 

[Delmer]

Maybe we should back up to the batteries. Like Old Doug said, jumper cables are no replacement for good batteries. If the batteries were drained, they would be frozen in the morning and wouldn't take a charge until they were thawed out, and might be ruined from the freezing also. Of course if you have two 12V's in series for 24V then any one cell being weak can be enough that it won't start cold.

I'd take the batteries out, warm them up, charge them up, test them, OR bring two different good batteries to start with and see what it does. Only then start worrying about the starter or engine drag.

 

[Randy88]

We have a half dozen starters a year off and worked on, I could be wrong but if the armature or field is bad you could have a dead short and draw on the batteries, I know it works like that on alternators, we've had issues on those in the past quite a bit. As for checking the starter on the machine, I deal with several rebuild guys, one swears by doing the checking while on the machine the other does nothing but swear at those that do that, he wants it brought in, so he can pull it apart and inspect it, and check over the armature and field coil and brushes and he does his testing while on his bench. Not sure which is right but the second guy has far less problems for me in the long run, if I'm having issues with dead batteries, I pull both the starter and alternator off and take it in to him and then pull the batteries out, charge them, leave them sit not hooked to anything and use a battery hydrometer on them before putting them back in again, then check the cables and ground's for GFS [green fuzzy sh@t] and make sure they are all clean and go from there.

 

[Mike L]

I once started a nice ladies pickup on fire at a gas pump trying to jump a starter.

:laugh that's the funniest thing I've heard all day!

 

[jeff112]

Just replaced a mt50 starter outside in o degree temp. The starter was dragging down the batteries,from internal shorting,The operators thought the batteries were low,hooked up two fresh batteries and jumped direct to starter to test,starter solenoid would click and starter would barley turn engine,removed and replaced starter,the machine then started right up.

 

[still learn'n]

Thanks guys been so busy with keepn other stuff running havnt had time to go back and work on it but will try out the suggestions and see where we get from there! Jerry