Improper Starter Engagement

[LTZ C20]

Hey all, suddenly my truck is having issues when I start it. I wanted to throw this out here incase some of the more experienced engine guys have seen and found or know of a solution.

My truck HAD the old style 500 lbs starter on it, I was having a heat soak issue, found it was the starter. At this point I found I can use a gear reduction starter as a replacement. So I got a reduction starter, installed it, was working good for a long while. Now, it grinding everytime I try to start it, it's requiring 3-4 tries to get it to start, being that it will grind the first 2-3 times before it actually engages properly and spins the engine over.

I got under the truck with flywheel cover off, had someone start it multiple times. The starter gear is only engaging the front half of the flywheel, so it will start to spin and then slip off and grind, slip off immediate and grind or spin and grind and the same time. The gear when extended, does not make contact on the full width of the ring gear, only the forward half. The flywheel is not damaged, just the teeth tips are a little scraped, still use able, the starter gear is pretty chewed up tho. Not gonna be use able for much longer.

The engine block is a late 90's Chevy 350, also known as an "R" motor (engine designation on a VIN #). The flywheel is a GM piece, new, proper to the block and crank shaft,  it is the flywheel that's supposed to be there. The starter is also a GM piece proper to the engine and flywheel for a late 90's 3/4 or 1 ton truck with an "R" motor. So all these pieces SHOULD work together properly, but aren't obviously.

Has anyone seen this? Do they know why? Is it simply a starter just not pushing the gear out enough? Possible shim or some kind of alignment issue between the starter and flywheel? What is my next step in the diagnosis? I would like to continue using some sort of reduction starter, preferably a GM one, as it has cured my heat soak problem, but if some kind of adjustable aftermarket unit is required then I'll have to use it.

Thanks guys.

[VileZambonie]

Replace the starter before you damage the ring gear. After you replace it, check for proper clearance. There is a how to in the tech section

[LTZ C20]

Saaawheeeeet. Thanks Vile, I'll do that. If it clearances good then I'm done? If it clearances out of spec then I go further with diagnosis?

[blazer74]

Sounds like the bendix might be bad.

As far as the measurement, just need to shim according to the instructions with the starter.

Unless you have a damaged flex plate or you will if you keep grinding it.


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[LTZ C20]

I had work order another for me, I'm either gonna park the truck for a couple days till it arrives or go to the auto parts store, get a stupid cheap one and put that on till the good replacement arrives. Then I'll do the necessary checks.

[LTZ C20]

This must be the how-to right?

http://forum.73-87chevytrucks.com/smforum/index.php?topic=20263.msg164837.msg#164837

[fitz]

Hopefully the new starter fixes it.
  Another thing to check is your battery cables. I had a small block with a similar problem. I spent hours swapping in a bunch of used starters from my parts collection. These were all starters that worked fine when I pulled them off trucks that I parted out. Now all of the sudden they were all having the same problem. It just seemed like they weren't fully meshing with the flywheel.
  After trying 5 or 6 different starters the I replaced the battery cables. The truck fired right up without any gringing. That was the problem all along. 
  Keep us posted.

[LTZ C20]

Covered that one already, battery cable are less than a year old, peaked at the positive while checking the starter, it's good.

[LTZ C20]

Ok, the fly wheel is installed correctly, as I expected it to be lol. Is it possible to have to shim a torque, putting washers or shims between the converter and flexplate mounting pads in order to force the ring gear closer to the engine. It appears the old starter is working, and the flex plate is not bent but I think with the converter bolted on, it's pulled the ring gear to far toward to the transmission? Is shinning possible or am I full of crap?

[blazer74]

Being that the tq converter floats on the trans anyway i say no.
Also if you had that much end play in your crank you have other issues.


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[bd]

Don't reach for wild solutions!  Focus and remain systematic.

Disconnect the positive battery cable from the starter and tape it up so it can't arc to ground - leave just enough of the terminal end bare to clip a test lead to it.  At this point, nothing should be connected to the 3/8" solenoid stud.  Remove the converter dust shield.  Clip a test lead to the solenoid "crank" terminal.  Touch the opposite end of the test lead to the bare spot on the disconnected and taped positive cable.  This energizes the solenoid and draws the pinion into the ring gear w/o cranking the motor.  The solenoid should energize and release with an authoritative snap & thud.  Now, you can accurately evaluate pinion engagement with the ring gear w/o losing a finger or snagging your hair in a rotating flexplate.  Check the pinion penetration and lash.  Typically, pinion gear penetration is 55 - 70% of ring gear width - the greater the better - but it will never penetrate 100%.  Don't concern yourself with shimming the starter at this time, unless the pinion engages the ring gear with an interference fit that prevents it from either engaging or releasing when power is applied to, or removed from, the solenoid.  Shim to resolve whining.

I concur with blazer74.  Do not attempt to shim the converter or flexplate.  I also agree, perhaps prematurely, that either the drive or solenoid is the source of the problem.  If the engine even hints at starting and overruns the pinion, a weak drive or broken drive spring can momentarily allow the pinion to spin out of engagement with the ring gear, but not clear it completely.  If the solenoid is not simultaneously de-energized it will hold the pinion against the face of the ring gear and grind away without reengaging. 

Another possibility is that the solenoid is energizing the cranking motor prematurely, before the pinion actually penetrates the ring gear.  Remember, the solenoid not only forces the pinion forward into the ring gear, but also closes a high-current switch that energizes the starter motor precisely after the pinion engages the ring.  Or, at least it's supposed to.

So, if the starter grinds immediately, before the motor actually cranks - the solenoid is at fault.  If it begins to crank and then grinds - the drive is the culprit.  Make sense?

Finally, don't overlook performing voltage drop tests across the battery positive cable, the starter-to-battery ground, and the solenoid battery cable stud-to-solenoid "crank" terminal, all while cranking the engine with the ignition defeated.  If adequate voltage isn't arriving where it should, when it should, even an otherwise perfect starter will labor and throw aggravating tantrums.

With no intention of demoting what others have posted, I think Vile has provided the best advice, thus far.  Replace the starter and then check the operating clearances.

[LTZ C20]

Oh Bd, my friend, great information as always. I'm gonna a have to address each paragraph one at time just to keep everything in order and clear.

P1. Don't worry, I wasnt. I was throwing an idea out just to see if that's something that is actually possible or common. I've never heard of shimming the converter, but shimming the starter, that's normal chevy lingo. Lol.

P2. I thing I did this in a different way. I already had the old starter off. I hooked jumper cables up to my battery, at the other end I hooked the positive onto the lug of the solenoid that has the large cable going from the solenoid into the starter body. Then I completed the circuit by touching the ground clamp to the body of the starter. It spins but did not kick out. Then I hooked the positive clamp up to the lug on the solenoid where the battery cable goes, ground clamp to the body of the starter, then I used a jumper wire to go between the battery cable lug and the much smaller lug. When I do this, the starter kicks out, spins and then stops spinning and kicks back in when I take the power away. I think what I've done is the same as you described just an a bench and not on the truck. Never did it push the solenoid out without spinning it. So did I do it right or did I miss something? Also, both new and old units operated the exact same during my "tests".

P3. I have not shimmed anything yet.

P4. This issue just starter the other day, haven't had a single issue with starting the truck until this.

P5. It does make sense. Sometimes it would grind immediately, sometimes it would begin to crank and then grind, sometimes it would crank then grind then crank then grind and then crank again all in just a few seconds. Ide give it a little gas as it rotates just to give it a shot to start so I don't have to keep grinding it.

P6. I checked when I replaced the battery cables, it was getting good voltage. Haven't had any electrical issues so I think it still is. Didn't do any checks tonight tho.

P7. I replaced the starter tonight, it's working normally. I would like to get this fixed before it happens again obviously. It was about 2 months between installing the first 1 and it turning into an AC Delco rock crusher 5 days ago.

[bd]

Bench checking the starter as you did would be "a limitation" if someone brought the starter into you for evaluation with the list of symptoms you reported.  Your resulting expression might be something akin to... .   Better to check it on the vehicle so you can evaluate the complete system and operating environment, including pinion engagement with the ring gear, which is the crucial observation missed on the bench - no?

The moment you begin making assumptions (e.g., the cables are only a year old... "I checked when I replaced the battery cables [one year ago], it was getting good voltage.  Haven't had any electrical issues so I think it still is.) is the moment you tie your shoes together.  You may well be correct in your assumptions, but experience humbled me and those I worked with many times over.  A word to the wise:  Low voltage can result in mechanical damage that festoons into catastrophe, sometimes hiding the original issue.  Check the operating voltages again, in a new unit of time, to help ensure your purpose:

...I replaced the starter tonight, it's working normally.  I would like to get this fixed before it happens again obviously.  It was about 2 months between installing the first 1 and it turning into an AC Delco rock crusher 5 days ago.

Don't make assumptions!

Since the new Delco starter is only a few months old, have your warranty admin replace it.  That's why warranty exists.

Now, circling back to the beginning and Vile's advice...

Replace the starter before you damage the ring gear. After you replace it, check for proper clearance. There is a how to in the tech section

 

[LTZ C20]

Thanks. The only issue with the warranty replacement I'm having is will they warranty it when it's working. Just the teeth are ground off. IF indeed the starter is the root cause, I have no problem with warranty replacement. IF the starter is NOT the root cause, I do not want to claim that it was because that seems dishonest to me and I don't want to get cause a trust issue with my work. So how do I approach honestly covering the cost of the new one.

[bd]

So, check e/g out as discussed, both mechanically and electrically.  If you don't discover an external cause, that leaves the starter (which, factually, sounds like the case).  It's not unprecedented.  It's not a question of dishonesty.  It's more a matter of routine.  If your warranty admin is worth his/her salt, he/she should have no qualms applying for AFA resolution and settling the claim successfully through the OEM.  With GM, it's almost a surety.