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Starter Motor spinning but not engaging flexplate - solenoid?
Gang,
Got my 66 Starfire (with 1970 455) from storage today. Started without a hitch drove great. Then I went to use it this afternoon and the starter motor just started spinning and not engaging with the flexplate.
My hunch is that the solenoid is not kicking the motor gear to the rear like it should, so I think I need to bolt on a new starter solenoid.
Does that sound right?
I picked up a new one today and have done the job several times before over the past 40 years, but am wondering if I should just do the solenoid, or put on a complete new starter motor that I have on hand for just such a situation.
What do you guys think - just swap the solenoid, or put a new starter motor & solenoid combo?
The lever that kicks out the starter drive (bendix) is mechanically linked to the contact disk that closes the circuit to spin the starter motor. If the motor turns, the problem isn't the solenoid. Most likely is a bad starter drive.
Joe
Thanks for the speedy reply. I’ll aim at doing the whole motor. I was kind of leaning that way, but I can’t remember quite how old it is.
Over past 10 years or so I’ve taken to scrawling the install date on my parts just to know how old (or young) they are. It’ll be interesting to see how old the current unit on there is.
The starter motor death culprit: Starter motor thrust seems to have destroyed the collar.
Did I do something wrong on install in 2017 that caused this?
And my date code from 2017. Looks like I may have replaced the solenoid in 2019, but I can't quite tell. Here's the pin that dropped out of the motor on removal, I'm wondering if it sheared off after years of use.
Sheared pin from inside somewhere? Any idea what might have caused this to happen?
Dropped the new starter in this morning, but have some shimming to do, it doesn't sound quite right yet.
Anyone got shimming tips for starter motors other than trial & error - or, well trial & grinding?
For anyone following along, my new/old starter (I bought in 2109, but never installed) needed 2 1/64” shims to line up properly.
While it was out I checked and cleaned up the wiring connections and routed them away from the exhaust manifold for longevity.
I also degreased & chased the bolt threads just to make reinstallation easier.
I get the slightest whine at the end of startup key release. I think this means I might need one more shim, but I want to drive it a little before adding the next one.
Sheared pin from inside somewhere? Any idea what might have caused this to happen?
Dropped the new starter in this morning, but have some shimming to do, it doesn't sound quite right yet.
Anyone got shimming tips for starter motors other than trial & error - or, well trial & grinding?
Cheers
Chris
Remove the solenoid from the starter.
Bolt the starter on the engine.
Pull the solenoid plunger so the drive teeth engage the flywheel.
If it engages freely no shims are needed.
If the drive does not engage the flywheel smoothly and freely, remove the starter and add shims until it does.
Remove starter and replace the solenoid.
Install starter with shims if necessary..
The "pin" you saw was actually one of the rollers from the starter drive clutch.
I suggest a few things be looked at after a starter drive failure. How are the teeth on the flex plate? Make a chalk mark on the flex plate and inspect the entire ring gear by rotating the engine one revolution (until the chalk mark re-appears) Check if your application had a bracket that attaches to the rear of the starter and the engine block. This prevents the starter from twisting during operation. It is common for these brackets to not be re-installed during starter replacement. The brackets are even more critical on larger displacement such as yours. Over the years I have seen starter drive and ring gears damaged, cracked starter noses (the aluminum front section of the starter) noisy starter operation, and engine blocks actually cracked at the starter mounting pad all due to the brackets that have gone missing.
The item you describe as a pin may be a roller from the failed starter drive.
Please keep us informed of your progress.
I suggest a few things be looked at after a starter drive failure. How are the teeth on the flex plate? Make a chalk mark on the flex plate and inspect the entire ring gear by rotating the engine one revolution (until the chalk mark re-appears) Check if your application had a bracket that attaches to the rear of the starter and the engine block. This prevents the starter from twisting during operation. It is common for these brackets to not be re-installed during starter replacement. The brackets are even more critical on larger displacement such as yours. Over the years I have seen starter drive and ring gears damaged, cracked starter noses (the aluminum front section of the starter) noisy starter operation, and engine blocks actually cracked at the starter mounting pad all due to the brackets that have gone missing.
The item you describe as a pin may be a roller from the failed starter drive.
Please keep us informed of your progress.
These are all very good points. There's another reason to reinstall the strap - it improves conductivity of the ground path from the starter to the block. Without the strap the return leg of the starter motor circuit runs from the steel motor housing to the aluminum nose piece to the cast iron block. Galvanic corrosion between the aluminum and the steel and cast iron increases resistance in the starter circuit, leading to hot start problems. The all-steel ground path through the strap doesn't have this dissimilar metals problem.
These are all very good points. There's another reason to reinstall the strap - it improves conductivity of the ground path from the starter to the block. Without the strap the return leg of the starter motor circuit runs from the steel motor housing to the aluminum nose piece to the cast iron block. Galvanic corrosion between the aluminum and the steel and cast iron increases resistance in the starter circuit, leading to hot start problems. The all-steel ground path through the strap doesn't have this dissimilar metals problem.
Thanks to you all for your thoughts. Great points.
My starter strap(s) is/are long gone. This is 1966 Starfire with an E-head 1970 (I think) 455. Heck, I had it rebuilt in 2013 or so. I don’t have any illusions about originality. Pretty nice car though.
I’ve never had a problem in 40 years or so with galvanic corrosion with missing the straps on both of my ‘66’s. But chemistry/physics is inevitable, so a strap would help avoid galvanic corrosion. Does anyone make a reproduction strap? I’d gladly bolt that on for both strength & corrosion protection.
For ease of hot starting, I use extra large gauge wires (1 gauge?) shrink-wrapped & get picky about clean electrical connections, especially with high amperage loads. Haven’t had troubles in years, but it could be luck.
I did check the flexplate when I removed the old starter. I’d judge it “driver quality” - not factory-perfect, no missing teeth, a few teeth here & there worn down a bit. But I’ve never had the starter jump a tooth or anything like that. If I recall correctly, I killed a flexplate in the 80’s or 90’s from ignorance & got careful after that.
Last night I wound up at 3 x 1/64” shims on the starter. I took it to my mechanic for a listen this morning. I was concerned that the “zing” at the end of the start was too many shims. He told me it sounded fine & that all new starters sound different from the ones they replace. Apparently people reacting to the “zing” sound is very common. It was great to have his view & confidence that I got it right, or at least close enough.
In case it helps, GM spec for starter motor bolts is 30-35 ft-lbs. Good starting point, thought Olds may be different.
May 28th, 2023, 03:17 PM
