Grinding noise when starting

1994 CHEVROLET SILVERADO
250,000 MILES • 4.3L • 6 CYL • 2WD • AUTOMATIC
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SWEETIE1965
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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.
Jul 29, 2018 at 3:09 PM
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ASEMASTER6371
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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
Jul 29, 2018 at 3:32 PM
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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?
Aug 3, 2018 at 3:49 PM
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ASEMASTER6371
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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
Aug 3, 2018 at 3:52 PM
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SWEETIE1965
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Yes, I inspected the flywheel. No broken or chipped teeth.
Aug 3, 2018 at 4:17 PM
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ASEMASTER6371
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Shims on the starter?
Aug 3, 2018 at 4:19 PM
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SWEETIE1965
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Yes, I placed shims as needed.
Aug 3, 2018 at 6:27 PM
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SWEETIE1965
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There was no shims when I removed the original starter.
Aug 3, 2018 at 6:28 PM
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ASEMASTER6371
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Did you use all of them?
Aug 3, 2018 at 6:57 PM
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SWEETIE1965
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No. There was I believe six came with the new starter. I used two.
Aug 3, 2018 at 8:11 PM
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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
Aug 4, 2018 at 1:02 PM
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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.
Aug 4, 2018 at 3:23 PM
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ASEMASTER6371
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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
Aug 4, 2018 at 3:26 PM
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SWEETIE1965
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Okay. Thanks for the advice. I will see if it solves the problem. I will let you know either way. Thanks a bunch again.
Aug 4, 2018 at 3:44 PM
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ASEMASTER6371
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You are welcome. Glad to help. Feel free to follow up with any other questions.

Roy
Aug 4, 2018 at 3:47 PM
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SWEETIE1965
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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.
Aug 5, 2018 at 10:51 AM
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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
Aug 5, 2018 at 2:10 PM
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SWEETIE1965
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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?
Aug 15, 2018 at 2:45 PM
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ASEMASTER6371
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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
Aug 15, 2018 at 2:57 PM
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SWEETIE1965
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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.
Aug 18, 2018 at 11:21 AM
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SWEETIE1965
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It is not on the transmission anywhere that I can see.
Aug 18, 2018 at 11:22 AM
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ASEMASTER6371
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Do you have a cable that hooks to the throttle body from the transmission?

If you do, it is a 4L60.

If not it is a 4L80.

Roy
Aug 18, 2018 at 11:25 AM
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SWEETIE1965
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Do you mean a passing gear cable? Yes, there is that and a cruise control cable.
Aug 18, 2018 at 12:17 PM
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ASEMASTER6371
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Okay, then it is the 4L60.

Roy
Aug 18, 2018 at 12:34 PM
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SWEETIE1965
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Thanks a lot.
Aug 18, 2018 at 1:04 PM
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ASEMASTER6371
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You are welcome.

Roy
Aug 18, 2018 at 1:10 PM
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SWEETIE1965
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If I was to swap engines in this truck, what year models would fit and is parts interchangeable with this engine? It is a 4.3.
Aug 22, 2018 at 1:08 PM
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ASEMASTER6371
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The long block is the same up to 1997.

You would need to strip down the donor block and change over all the externals to the donor.

Roy
Aug 22, 2018 at 1:12 PM
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SWEETIE1965
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Thank you.
Aug 22, 2018 at 1:34 PM
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ASEMASTER6371
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You are welcome.
Aug 22, 2018 at 1:47 PM
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SWEETIE1965
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I repaired my truck. The flywheel was not broken or anything. The torque converter bolts was not even hand tight. Whoever changed the transmission did not tighten the torque converter bolts like they should be. Now there is no noise coming from under vehicle at all. Thanks for your help.
Aug 28, 2018 at 7:50 AM
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ASEMASTER6371
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Good find. Glad to hear it was a simple fix.

Roy
Aug 28, 2018 at 8:00 AM
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SWEETIE1965
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Thanks again for all your help and advice. I recommend you to anyone.
Aug 28, 2018 at 10:30 AM
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ASEMASTER6371
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Thank you for the kind words.

We are always glad to help.

Roy
Aug 28, 2018 at 10:41 AM
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SWEETIE1965
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On my truck, the left signal light is blinking real fast. I checked the bulbs they are all working. I changed the rear light circuit board. Everything else works fine. What could be doing this?
Sep 17, 2018 at 10:08 AM
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SWEETIE1965
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The bulb is an 1156. It only operates the signal light.
Sep 17, 2018 at 10:09 AM
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ASEMASTER6371
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It could be the flasher itself.

Do the fronts and rear work together?

Roy
Sep 17, 2018 at 11:53 AM
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SWEETIE1965
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They work together. Front works but blinks fast also. Passenger side blinks normal. I changed the circuit board and the bulb. Still doing the same thing.
Sep 17, 2018 at 12:16 PM
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ASEMASTER6371
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Please start a new question since we are off track from the original issue.

Roy
Sep 17, 2018 at 2:41 PM
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SWEETIE1965
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Right signal lights blink real fast. I have changed circuit board, and bulb. Both signal lights on driving side blinks at same time. The passenger side works fine. All other lights work properly but drivers side signal light. What can cause this?
Sep 17, 2018 at 3:01 PM
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ASEMASTER6371
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You need to close out this question and start a new one.
Sep 17, 2018 at 3:04 PM