Hot Rods What are the causes for a (new) starter motor that barely turns over?

Hey everyone

Hope all is well

I’ve spent my day trying to figure out what’s wrong with a starter motor I purchased for my 283 SBC.

The solenoid kicks out hard, but the motor itself is super sluggish. Basically it starts and just grinds to a halt every time. I pulled it apart and gave the 4 pads a clean, put it back together and it almost worked okay for a few seconds but quickly went back to slow, and stop. I’m running it off a fully charged battery in a running car. I can’t figure out the cause. I’m thinking it’s a dud but is there a potential solution? It is a brand new starter motor!




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Just to clarify, this is testing it out of the car?

 

Yep out of the car using jumper leads. The leads are getting super hot so this would indicate a short I guess?


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Smell the insides ,if it overheats it will stink like it burnt. If a bushing s to tight it will slow it up but not smell the same. Why not take it back and get another.?

 

My thoughts also.

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I'd agree, I would have taken it back. taking it apart may have voided the warranty.
I've pulled freshly rebuilt starters apart that had dry bushings in them as they don't lube them like we usually do when we do our own.
Is there any sign where the armature is rubbing the fields? Either on the armature or on the fields? someone could have chucked it in a vise or dropped it before it went to the rebuilder. They turn the commutator and back cut it along with checking for electrical issues but have missed one being slightly out of round. I've never seen a starter housing be out of round though.

Personally I'd put it back together and take it back and exchange it for another one having the store test the other one before I left the store.

I was trying to think of what starter that is and if memory serves right it is a real pain in the butt to work on anyhow.

 

If your jumping the starter with jumper cables in the vehicle that may be your problem the cables won't give enough to get the starter to work, generally the cable wire is too small to carry the amps, sure the solnoid will work as it has a less draw than the starter but the starter won't.

 

Try reading what has been posted already before adding your 2 cents worth and looking foolish!

 

WTF?

 

I recently purchased a rebuilt starter for a SBC from a big name parts chain. It wouldn't crank worth a hoot when hot. The problem was an internal ground wire barely hanging on at the housing due to a poorly soldered connection.

 

If you are using cheap jumper cables with big gauge wire they will always get hot. You need the ones with fine wire like welding leads. Remember the voltage Travis on the surface of the wire and not thru it. The more finer strands the better.

 

I've bench tested many starters with jumper cables, never the cables cause an issue.
I'd like to hear more about voltage traveling on the surface of the wire, and not through it....

 

Me too. Lippy

 

Most of these jumper leads are now aluminium and not copper. Makes a big difference.


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That's an actual phenomena, but not applicable here. Known as the 'skin effect', it can be an issue at high voltages and/or frequencies and is something power utilities have to deal with in their transmission lines. This term became popular with the high-end audio crowd when trying to hawk expensive speaker cables. Doesn't apply there either...

As to aluminum vs copper, yes, aluminum isn't quite as good a conductor as copper but if the wire size is bumped up 1-3 sizes compared to copper, you'll never know the difference.

 

Yes, I knew that.

 

With the starter(or any motor) free wheeling(bench testing) there will be very little load on the cables, and the starter itself should spin up no problem. Cables could be cheap 10' long(manky grocery outlet type jumper cables) and the starter(with a fully functional and charged battery) will spin it with ease.

If not there is a mechanical problem(bearing , bent shaft, wrong grease, faulty bendix, or housing distortion) causing binding, then it would most likely be an electrical problem(bad commutator/brushes, damaged windings, bad contact(s) etc).
If the bendix drive shoots out no problem, verify that the switch inside the solenoid is allowing proper voltage to the windings(check for voltage drop across the switch contacts)
If no voltage drop then the switch is most likely fine and there is something wrong with the rotor.
It could be possible that some how a magnet on the stator(housing) is flipped causing the rotor to lock, but I doubt that. Unless it's some super snazzy unique starter, just bring it back for a replacement.

In this case 'skin effect' is what he is referring to. From my apprenticeship days that I can recall...
AC power will more easily travel on the surface area of the wire than through it due to the constant changing polarity/voltage and eddy currents that are induced into the wire core itself. Basically the eddy currents cancel out the power flow towards the middle of the wire core, which forces the power to travel near the skin of the wire.
Stranded wire is better for use in AC, or hollow tubes for antennas at higher frequencies(hertz) as the signal will travel closer to the skin of the conductor and not through the middle. More strands more surface area(skin effect). But skin effect is not a concern with normal wiring. In the case of 120V/60Hz it would take a depth(not diameter) of ~8mm(5/16") in solid wire before the eddy currents/skin effect become an issue. And since most wiring never ever requires that large of a diameter of solid wiring, it is never really a concern or brought up. Again this is more of a high frequency issue, radio antennas, data transfer, communications, etc.

DC power does not have the alternating flux of + to - voltage/current so it just pushes the electrons through the wire with no issues of inducing eddy currents in the wire itself.
And in the case of vehicles, specifically those pertaining to this board, skin effect will never be an issue.

When wiring the two major concerns are proper cross section for the given ampacity and desired insulation for the application, insulation will affect ampacity of wiring due to heat retention. Then wiring is resized due to ambient temperature due to heat induced resistance.

 

Yes, and you forgot to mention ampacities change (according to the NEC) with a single current carrying conductor, vs "up to 3 current carrying conductors"...pages 62-65 of my older 2004 Refernce manual-i still use it a lot

Then there's the concern with 4-6 conductors, 6-8..etc...and the continued de-rating factors, not to mention continuous loads or non continuous loads for OCPD as well.

 

Bad out of the box. You didn't say where you got it, but I'm guessing it was your turn to draw the short straw in the over-the-counter lottery. Sorry, man. Years ago I worked in gas station next door to a big national auto parts chain. Their fail rate on remanufactured parts seemed to be one in four. We wouldn't install their shit. I'm lucky to live close to a really good auto electric shop. Their rebuilds cost more, but worth it to avoid the lottery.

 

I see two issues, the armature is hitting the magnets and you have a poor connection on the solenoid to starter connector (arcing)

 

My experience with 12V systems is if you do voltage drop calculations for each wire length/circuit and size the wire to keep the drops below 3%, the ampacity will take care of itself....

As for parts house rebuilds, I used to know a guy who worked at a major rebuilder (they were an 'official' rebuilder for several of the OEMs) and they considered a 20% return rate as 'acceptable'....

 

Rick, I believe those are balancing gruves on the armature, and that might be a sign, as it was way out of balance. Bones

Ok, Rick, I went back and looked closer, I do see the drag marks now. Those balancing gruves caught my old eyes first, Bones

 

Being that far out of balance and rubbing suggests a bent armature but how that could get by quality control suggests there might not be any quality or control.

 

It's sad, but in today's world, you should have a new starter checked at the store before you leave. Sucks.

 

Ah -ha...from what I can see of the box, is that starter Pro-comp brand? If so, that may explain it, do a search because they have a reputation for crap as bad as Hoffman.

(I've read the whole thread and you don't mention the brand, and I am only guessing, so I could be wrong.)

 

From 1st post:

He does not say whether or not the starter is still in the car of the starter application - which is why I sought to clarify whether he was bench testing or not . As it turns out, he is bench testing.

It never hurts to clarify information - which BTW is different from giving two cents.

And mine was the first response I might add.

 

I agree with you. It wasn't clear and your "two cents" asking for clarification made sense and wasn't foolish at all (unlike the guy saying it was).

Back to the OP, have you returned it yet?


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Hey guys thanks so much for the help. I believe I'll take this back to the store when it opens tomorrow. Hopefully unbuttoning it to take a look hasn't voided my warranty. Yes there are certainly scrapes on the side of the armature from hitting the magnets. My jumper cables are quite okay I think. I don't imagine they'd be an issue.

It does seem that automotive parts with the word 'pro' in the name are usually quite the opposite! Its my own fault I guess. It was rather 'economically priced'. The starter itself doesn't smell hot, but the leads actually begin smoking if held on for 5 seconds.

 

You know, you're right, but it never occurred to me to do just that. It would be worth it if nothing else than to see the look on the kids face when you ask him to do it. Good idea!

 

This is not true, please stop telling people this. Copper is a conductor, the entire wire, no mater how big or small, carries current as electrons move along from atom to atom. A 00 cable will carry the same amount of current, whether it is made of fewer strands of heavy wire or many more strands of fine wire, it doesn't matter.

There is something known as "skin effect", but that only involves very high frequency alternating current, not direct current. Please, this is an urban legend that needs to die, stop repeating it.