Electric motor starts only pushed; and how do I open it ?

[adrianTNT]

Hello.

I have a 12V motor from an oil pump, an AWD/4x4 differential oil pump, and I am unsure if it is burned or not.
I put power on it and it remains still unless I give it a turn by hand, then it starts and it appears to increase its speed slowly.
It has only ground and one pin, so two wires.

1) Can it be burned and that is why it doesn't start by itself ?
2) Anyone knows a way to open these?

Photos are here:

http://tntgallery.com/page-244-32219.html

Thank you.

 

[waross]

Throw it away and buy a new one before you lose the differential.
Open it with a hacksaw. It is not serviceable.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[DRWeig]

I'm going to guess that your motor is as corroded on the inside as it is on the outside, perhaps within one of the bearings as well. Not worth opening up. It looks to me like it there are four rivets and stakes around the edges holding it together.

Best to you,

Goober Dave

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[adrianTNT]

I cannot find a new motor (part number was washed out) and the complete pump from Mitsubishi is between 1500-3500$.
I heard some people mention this happens when "start capacitor" of the motor is burned, that makes sense, but I don't know if this motor has a capacitor (maybe inside).

Video should apear here soon:

http://www.youtube.com/watch?v=KzmGK3KlaEY

 

[MiketheEngineer]

Take it to a motor shop??

 

[OperaHouse]

I have rebuilt a number of transfer case motors. One reason for the slow startup is sticking bearings that have dried out oil. As it starts to spin they heat up and a little more oil comes out of the sintered bearing. If one end is capped, drill a little hole to get oil in. Transmission fluid works some time. I use a brake lighr in series with the motor to prevent burning it up. When it easily starts up with the lamp in series it is ok. It can take several hours running to get the oil to soak in. There are no starting capacitors with DC.

 

[jraef]

Capacitor starting issues are related to AC motors. Yours is DC, there is no capacitor inside.

If it is not generating enough torque to turn itself without assistance, it is either bad brushes or the motor it burned out. If you can see two brush access ports on the end of the motor, then you can replace the brushes. If not, it is a throw-away motor. Chances are about 99% that on an automotive winch, it is throw-away.

In the image below, the brush access ports are the slotted dark gray circles on the right side end of the motor. Most of them look similar.

If you insist on trying to repair it, remove it and take it to a motor rewind shop that says that they work on automotive starter motors, the technology is similar. If you want to try to fix it yourself, you are in need of a mental exam.

Last word, this is not a DIY (Do It Yourself) website, it is a place for electrical engineers to help each other with perplexing work issues. Most likely this thread will disappear in short order once the Admins see it.


"Will work for salami"

 

[DRWeig]

I just want to emphasize OperaHouse's last sentence. It's a DC motor, there is no start capacitor.

Best to you,

Goober Dave

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[adrianTNT]

Thanks for your replies.

I will look for more motor rewind shops tomorrow, the one I tried today told me to came with the motor opened

Maybe I should have mentioned that it stopped working when I first started the car at very low temperature, after it was under -15 Celsius, Mitsubishi repair manual says that this pump works harder in lower temps, maybe something in the motor failed.

This is a video of older pump where motor is very similar but it can be opened, at 21:10 it shows bearings and all:

http://www.youtube.com/watch?v=ZrYjQat4KGE#t=21m10s

Right now I am thinking the lower bearing is stuck, as OperaHouse said.

 

[LionelHutz]

If you look in the top left corner or on the left side of the 3rd picture there are punched in spots in the outer case. I can see 3 or 4 other spots like that and it appears it'd have about 8 to 10 spots around the outside. My guess would be that those outer case punched in spots push a bit of metal from the outer case over that plate holding the bearing. Grind those spots back and it'll probably come apart.

 

[OperaHouse]

Nice video. reminded me of the high capacity fuel pump I just rebuilt. The real problem I had with it was the insertion of the rotor into the brushes. I must have blinked and missed it. That step is usually a nightmare. I have used thread, pins, shims and other tricks to get them in place and even with experience it taks about four tries.

 

[adrianTNT]

I took it to a mechanic today and cut inside that circle with a lathe (?! I think this is correct word).
Bearings look ok, one of the brushes wire is black/burned, the other is gold, I think that is my problem Will try to replace it tomorrow.
If anyone is curious how it looks:

http://tntgallery.com/page-245-87983.html

 

[DRWeig]

Thanks for following up, adrianTNT! You're a good photographer too.

I always appreciate hearing from someone who finally resolved his problem.

Best to you,

Goober Dave

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[waross]

I hope you marked the case before you took it apart. It must be re-assembled in the exact position that it was in originally. Both for proper commutation and so that the power plug will align properly.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

Good work, hopefully you can get a brush and get it working again.