Grinding noise when starting

Tiny
SWEETIE1965
  • MEMBER
  • 1994 CHEVROLET SILVERADO
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
When I start the truck, it sounds like a grinding noise coming from under vehicle. Removed the starter and had it tested at a local AutoZone store two different times. First time it failed the drive extension test. The second time it passed. So I put the starter back on. It is still doing the same thing. What are your thoughts could cause this grinding noise when engine is first started and stopping the engine? It just started this a couple days ago.
Sunday, July 29th, 2018 AT 3:09 PM

42 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good afternoon.

If it failed the test on the bench, it is no good. That is a no load test.

Cranking the truck is a full load test. You need to start with a replacement starter motor.

Roy
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Sunday, July 29th, 2018 AT 3:32 PM
Tiny
SWEETIE1965
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I changed the starter. It is still making a grinding noise while starting and when shutting off the engine. I cannot figure out where it is coming from. I know I have an oil leak from the rear main seal which still holds normal oil pressure. What can be making this noise?
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Friday, August 3rd, 2018 AT 3:49 PM
Tiny
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It could be an alignment problem between the starter and the flywheel.

Did you use the same number of shims you removed?

Did you inspect the teeth on the flywheel for and damage such as half gone or broken teeth?

Roy
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Friday, August 3rd, 2018 AT 3:52 PM
Tiny
SWEETIE1965
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Yes, I inspected the flywheel. No broken or chipped teeth.
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Friday, August 3rd, 2018 AT 4:17 PM
Tiny
ASEMASTER6371
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Shims on the starter?
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Friday, August 3rd, 2018 AT 4:19 PM
Tiny
SWEETIE1965
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Yes, I placed shims as needed.
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Friday, August 3rd, 2018 AT 6:27 PM
Tiny
SWEETIE1965
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There was no shims when I removed the original starter.
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Friday, August 3rd, 2018 AT 6:28 PM
Tiny
ASEMASTER6371
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Did you use all of them?
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Friday, August 3rd, 2018 AT 6:57 PM
Tiny
SWEETIE1965
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No. There was I believe six came with the new starter. I used two.
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Friday, August 3rd, 2018 AT 8:11 PM
Tiny
ASEMASTER6371
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If the flywheel is okay, then you will need to play with the shims. The reason they are there is because when they rebuild the starter they plane the nose. They give shims equal to the amount the cut off the nose.

It sounds like your alignment is off.

Roy
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Saturday, August 4th, 2018 AT 1:02 PM
Tiny
SWEETIE1965
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Would it make the same noise when starting as to the noise when I shut the engine off? It does not affect the way the engine runs. It is just an aggregating noise like grinding noise while starting and shutting the engine off.
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Saturday, August 4th, 2018 AT 3:23 PM
Tiny
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The starter may be too close to the flywheel or the gears may be making contact.

That is why you need to work with the shims.

Roy
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Saturday, August 4th, 2018 AT 3:26 PM
Tiny
SWEETIE1965
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  • 165 POSTS
Okay. Thanks for the advice. I will see if it solves the problem. I will let you know either way. Thanks a bunch again.
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Saturday, August 4th, 2018 AT 3:44 PM
Tiny
ASEMASTER6371
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You are welcome. Glad to help. Feel free to follow up with any other questions.

Roy
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Saturday, August 4th, 2018 AT 3:47 PM
Tiny
SWEETIE1965
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  • 165 POSTS
I put one shim at a time to try starting the truck. I got up to all 6 shims that came with the starter and it is still doing the same thing.
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Sunday, August 5th, 2018 AT 10:51 AM
Tiny
ASEMASTER6371
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It may be the starter itself or it could still be the flywheel.

You need to have someone look at it for you to see why it is doing this noise. Sorry, I cannot do any more from here.

Roy
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Sunday, August 5th, 2018 AT 2:10 PM
Tiny
SWEETIE1965
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  • 165 POSTS
I had a repair shop look at my truck today. The mechanic said the flywheel is either loose or broken. How can a flywheel break when the truck does not get abused like drive fast, spin the tires or anything like that? I drive like a normal person would. I know I have to get it repaired but I am curious how can this happen?
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Wednesday, August 15th, 2018 AT 2:45 PM
Tiny
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Most times the flywheel cracks from moving back and forth.

This movement comes from a worn thrust bearing in the crankshaft. When that wears, the crank moves back and forth and that movement will break the center of the flywheel.

Roy
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Wednesday, August 15th, 2018 AT 2:57 PM
Tiny
SWEETIE1965
  • MEMBER
  • 165 POSTS
On my 1994 Chevrolet c1500 with a 4.3 liter engine, I know I have to replace the flywheel. What size should the transmission be? A 4L60 or a 480? I just do not want to buy the wrong flywheel.
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Saturday, August 18th, 2018 AT 11:21 AM
Tiny
SWEETIE1965
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It is not on the transmission anywhere that I can see.
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Saturday, August 18th, 2018 AT 11:22 AM

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