Starter spinning but not catching, cant figure it out.

[ask92]

Ok so this the story. I'm swapping a 89 engine with 87 elecs(TPS,CPS,ISC,ect).. When I turn the key the starter engages for a split second(the engine rotates 1/10th of a turn) but then retracts and just spins. Things to consider:

-The flywheel was torqued down to 55lbs in a star pattern.
-When the starter isn't on the engine with load, the starter goes out and spins normally.
-The pressure plate bolted onto the flywheel perfectly.
-The engine spins freely using a ratchet so its not locked up.
-The battery is fine, it started our v8 jeep fine, i took it over to the supra, and got the symptoms
-There are no grinding noises at all. It sounds normal, just doesn't have the engines load.
-The starter was used 1 month ago and worked fine, hasnt been dropped or anything.

Reasons i think MAY be the issue
-There is no major engine to chassis ground
-The harness was cut up pretty badly, and i had to redo a bunch of plugs
-I'm missing the tranny electrical sensor that goes under the shifter(not sure what is it is, maybe reverse lights?)


Anyone have any ideas?

 

[hvyman]

Try manually applying power to the starter via wire from batt to starter and see if it cranks normally. If it does you problem is in the wiring.

 

[supraguy@aol]

That sensor going to the back of the tranny is either the reverse light switch, or the abs sensor.
And make sure there is a good ground between the engine and the chassis, otherwise electricity will start finding more expensive paths to take.

 

[Nick M]

The magnetic switch that is supposed to hold isn't holding. Or so it seems from here.

 

[ask92]

Try manually applying power to the starter via wire from batt to starter and see if it cranks normally. If it does you problem is in the wiring.

Sounds like a great idea, ill try it tomorrow.

The magnetic switch that is supposed to hold isn't holding. Or so it seems from here.

But it works fine when its not on the engine?

 

[toyotanos]

My money is on the sprag/one-way clutch being faulty.

Here's my reasoning: For the starter to run at all, the plunger in the solenoid housing (on the starter) has to move downward to make the high-amp connection. Attached to that plunger is a pin that pushes the starter gear outward to engage the flywheel teeth. (this is really nice, because the gear is engaged with the flywheel teeth before the starter motor runs in most cases) Because the motor on your car is running but not cranking the engine, that leads me to believe the gear is engaging for a split second, but the one-way clutch can't hold the torque.

 

[Nick M]

But it works fine when its not on the engine?

The pull in coil quits working after the pinion gear engages. The magentic force of the hold in coil is supposed to hold it after the pull in coil is de-energized. That is activated by a magnetic switch on the plunger.

---------- Post added at 10:14 PM ---------- Previous post was at 10:12 PM ----------

Because the motor on your car is running but not cranking the engine, that leads me to believe the gear is engaging for a split second, but the one-way clutch can't hold the torque.

That very well could be. Often this is accompanied by a high squeal of the clutch.

 

[ask92]

Dear lord......This is possibly one of the worst fails ever.

The starter is working perfectly. I pulled the plugs before starting so there would be no issue with compression on the bearings. And because of this the starter sounded strange because there was 0 load on the engine. When I put direct 12v on the starter I was in the bay instead of just in the cabin and could see the engine turning...*sigh* A full day of troubleshooting and BS for nothing...

thanks for all your help guys, i hope this thread will help some people searching some day. Commence with the lulz...

 

[toyotanos]

But no matter if Nick or I am right, a new starter is the fix for both conditions! (just be sure to inspect the teeth on the flywheel/flexplate while you have the starter out)

Edit: lulz Glad you didn't need a new part