Starter Motor Rebuild?

[GDII]

The brush surface/slip ring looks very dark. Unless thats a normal electric motor thing.

[Benckj]

That’s normal on the comutator to have a dark colour. I’ll clean them up before re-installing. Not a lot of carbon dust present and brushes are in decent shape.

Main issue is the selenoid plunger contact surfaces. Both sides are very rough and getting a decent electrical connection would be hit & miss. Believe this is my root cause of non starting.

Should be easy enough to redress the electrical surface and grease up moving parts then give it a test run. I’ve had some strange issues with engine cranking ok but not stating for some time now as I think back. Worked fine on full battery charge but not when sitting for several weeks/month.

[GDII]

Yeah I think you are right. Hopefully you can clean that up. It seems to be a common fault for starter motors.

[Benckj]

Everything cleaned up quite well and will hopefully reassemble and install this weekend. This is not something I’ve seen in any forum reports before so really didn’t expect to be an issue with MR2. Maybe it’s more common than thought and others simply replace starter after it acts up?

All the same hope it turns out to be my fault and doesn’t lead to further investigation. Looks Ike we sold my wife’s Audi TT and new one doesn’t arrive until Christmas so MR2 my become a DD. Would like to make sure wife doesn’t get stranded anywhere.

[GDII]

Apparently hitting the starter with a hammer or a pole makes them work again?

[Benckj]

Apparently hitting the starter with a hammer or a pole makes them work again?

Probably would have worked in this case as if the selenoid could be jarred a bit it may rotate and then make electrical contact when energised. Could also free a stuck brush. Hit & miss but easy way to get you going again.

Hope rebuilding solves my issue without the need for a large hammer assistance.

[Benckj]

Installed starter today and used plenty of copper coat on threads. Turned the key and only selenoid clicked. Voltage seemed decent at 12.2 so checked starter relay and it was fine. Decided to chuck a battery charger on to see if the new battery needed a boost. Fired up first pop. Left charger on for a couple hours and now starter cranks like it never has before, every time. Time to take a decent run and blow the cob webs off.

[GDII]

Dead battery I'd say. Just because it has the right voltage doesn't mean it's actually working properly.

[Benckj]

Initially I thought so, until I took out and ran a full 7 stage charge/ discharge test. It did act a bit strange during initial cycles but being a 720cca AGM battery I thought it may have sulfided cathode.

Bought a new battery of same spec and starter acted much the same even with the charger connected. This battery is for a diesel 4x4 so should have plenty of grunt for a 2l petrol car.

Think it’s all sorted now as it’s cranking like never before. Took for a 15min run and alternator is sitting on 14.2vdc so looking decent enough. I upgraded alternator a few years ago to 130amp so should provide enough current as long as I can take for an extended run now and then.

[GDII]

Boom! I knew it!

Keep it trickle charged! My current new battery I bought recently doesn't hold charge well because I let it run flat too many times. My bad. So it stays on the charger.

[Benckj]

Boom! I knew it!

Keep it trickle charged! My current new battery I bought recently doesn't hold charge well because I let it run flat too many times. My bad. So it stays on the charger.

Only partially correct. Battery condition is certainly part of the problem but the arcing contactor in the solenoid is the root cause. The starter is now turning like it never has before and this is not simply due to a new battery. Others may want to take note that a sluggish starter may not be soley due to old or faulty battery.

[Benckj]

Just an update to this starter issue after a years running.

Engine still cranks very quick regardless of how long I leave the car without using. Starter does sound quite strange though like its not engaging correctly with ring gear. I've checked all the obvious things like loose bolts, etc and nothing wrong. Plan to pull starter again and have a look at gear & internals to see if there is any signs of wear, etc.

Have also purchased a second hand starter from TradeMe to install as a comparison. May pull this one apart and see if it shows same signs of electrical wear like mine did.