Reman Starter Grinding (Denso)

[suprarx7nut]

Installed a fresh Reman Starter from Denso. Here's the chain of events along with video evidence:
1. First Crank: Thud. Bendix did not completely throw or did not attempt to spin.
2. Check voltage in battery, all is well (>12V).
3. Second/Third Crank: Horrible grinding sound, engine did not crank.
4. Removed Starter.
5. Comparing the teeth it seems there's a lead in feature on the old starter teeth, but not the new starter. Throw out distance is the same for each.

[video]https://youtu.be/lI4OXzPqxQI[/video]

Do you think the reman starter is faulty in that it's missing the beveled lead-in feature? That seems to be a likely cause for the grinding and lack of engagement. Denso's pictures show flat teeth on all their MK3 starters while Bosch units have a nice beveled lead in.

What's your take on this?

Thanks!

 

[Maple191]

12.05V is weak. Whats the Voltage while cranking?

 

[JDMMA70]

My original starter's gears do not look like that, they look like the reman Denso.

 

[suprarx7nut]

12.05V is weak. Whats the Voltage while cranking?

Damn, you're right. Not sure why I had 12V or higher in my mind as acceptable. Hmm... I'll get my charger on the battery and perhaps try again after it's charged back up to 12.6 or higher.

It would be nice if this was as simple as insufficient power...

 

[Jeff Lange]

The teeth should be flat when they're new. The one on the right looks like they're pretty worn. It looks like the Bosch starter uses a different design than Denso. The Denso one you've got looks correct and what the original starters that came from Toyota looked like.

Jeff

 

[Nick M]

Can you turn over the crank bolt with a long wratchet/breaker bar? You can check while the battery is charging.

 

[suprarx7nut]

The teeth should be flat when they're new. The one on the right looks like they're pretty worn. It looks like the Bosch starter uses a different design than Denso. The Denso one you've got looks correct and what the original starters that came from Toyota looked like.

Jeff

Awesome, thanks Jeff!

Can you turn over the crank bolt with a long wratchet/breaker bar? You can check while the battery is charging.

I can turn the crank by hand, yes. Just verified it.

Later tonight I should have time to get the starter back in and see if it will engage correctly with a full charge.

I'll update with a (hopefully more eventful) video.

Thanks guys.

 

[suprarx7nut]

Well... nothing changed. Video below. Same awful whir/grind and no cranking whatsoever. Battery voltage is shown in the video. It seems stable enough starting at 12.75 and dropping to a little more than 11 during cranking.

At this point I just think the starter is faulty. I'm perplexed how that could be, but I'm not sure what else would cause this. The car side of things should be good. My old starter worked perfectly fine. This swap was supposed to be a convenient preventative maintenance item while I had the intake out. Two R&R's later and this is looking like a bad decision to perform preventative maintenance, haha.

Anything else I should check before putting my old functional starter back in and sending this off to Rock Auto for a swap/refund?

The starter is bolted in, flush against the bell housing. The throw of the gear is the same distance as my known good starter. The gears are similar (new one is not worn on the teeth). I don't get it! :runaway:

[video=youtube;zLP56w6QFuE]https://www.youtube.com/watch?v=zLP56w6QFuE[/video]

 

[Nick M]

I'm not sure what else would cause this.

A bad flywheel or flex plate. Meaning the grinding noise.

I didn't watch the video. You need to do voltage drop on the large wire. One probe at the starter, the other on the battery. About .1 or .2 at the most through the connections. Bosch, who sells starters, once stated that 80% of the starters they get (core) have nothing wrong with them.

edit: While it is out, you can have an Autozone or similar place bench test the starter.

 

[suprarx7nut]

Good suggestion, Nick. I'll check. The battery cable is a new custom fit one I made from a generic cable from Autozone. I'll measure it to be sure.

I did look at the flywheel and it seemed fine. No odd wear I could see. I'll try to snake my arm down there to grab since video of it.

Sent from my XT1060 using Tapatalk

 

[JDMMA70]

Did you bench test the starter before re-installing?

 

[suprarx7nut]

Did you bench test the starter before re-installing?

I applied 12V to the solenoid terminal to see that the pinion would extend outward and it did. I did not perform any further testing.

I'm honestly not sure what the following instructions are supposed to be telling you to do so I did not perform these tests: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=ST&P=11

I spent a few minutes reading and re-reading it and I'm still not sure what's supposed to transpire to test the starter according to the TSRM. I could spend more time on that if those tests are helpful for my issue. I saw that with 12V applied to the solenoid it threw out just like it should and called it good.

More test results:

Resistance from B+ to starter + post: 0.2-0.3 ohms including about 0.2 ohms for the leads on my DMM. Essentially no resistance.
Voltage on battery: 12.45V
Voltage on starter solenoid terminal (harness side) during cranking while disconnected from starter: 11.75V

At this point I think I need to take it out and have it tested at O'Reiley's down the street unless anyone has a suggestion to try while it's still on the car.

 

[Nick M]

You can roll the flywheel over while the starter is out and look at the teeth. You may or may not be surprised.

 

[suprarx7nut]

Well I'm completely befuddled, confused and defeated.

1. The starter tests good on the automated testers at the parts stores. Two stores said it throws and spins just like it should.
2. Voltage drop across the large 12V cable to the starter is lower than 1mV. My Fluke DMM reads 0.000V between B+ and the starter contact. If I read voltage to ground I get the same reading at the starter and battery.
3. Voltage drop across the solenoid wire while starting is around .5-.8V.
4. Old starter worked perfectly fine.
5. Flywheel has no missing teeth and wear seems minimal/normal. All teeth have sharp, square corners at their peak and do not have any of their engine side face worn away.

I'll install the old starter again and see if that works. On the plus side, my starter removal and install procedure is very efficient. It's still a pain, but I got the last one out in around 13 minutes (not including jacking the car up). Silver linings and all...

 

[suprarx7nut]

I installed the old starter. It cranked immediately, just like normal. There must be some fault with the rebuilt Denso. Back to Rock Auto it goes.

I opened up the back cavity where the contacts reside. The rebuilt Denso had beefy contacts. My old starter had 2.0mm thick contacts while the rebuilt unit had 2.5mm thick contacts. At this point my only hypothesis is that perhaps the contacts being that much thicker completed the starter motor circuit too early in the throw and spun the pinion before it was engaged. 0.5mm (0.020") seems like too small a difference in the throw to make that distinct of a difference, but that's all I can come up with.

 

[SupraBro]

I had this happen to me once, I went through the same steps, benched it and acted normal. its internal of the starter, the motor inside the starter would separate when it would try to move the flywheel. So it pops out, locks on the flywheel, then the starter motor is just spinning.

 

[destrux]

I had the same problem with a starter. I suspect there's a casting that's very similar to the one we need but is just slightly different enough to cause binding. I ended up rebuilding my original myself.