Single clunk noise when trying to start?

Tiny
BRANDONLANGLOIS
  • MEMBER
  • 1994 CHEVROLET ASTRO
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 340,000 MILES
Hello. It's been a few weeks since this happened to me. I was on my way home from picking my girlfriend up from work when suddenly the engine lost all power just before a stop sign. There was a tiny bit of a grinding noise the instant it happened and there was no crank when I went to restart the engine. Only one single Clunk of a noise.

I awaited a car with a boost from a friend but boosting had no effect at all. I got it towed to my driveway and tried to boost it with a big battery pack, and still nothing. I even took the batter out of my 2015 Chevrolet Cruze and attached that, And still. No crank only a single clunk.

Back to when we had boosted the car, we suspected it could be the starter so we gave it a couple whacks with a hammer, it had no effect. The starter does have some rust on it, but I've never had an issue starting it once before, she always used to start in an instant.

That morning I had found out that my radio was not working. I figured out that it had stopped working due to my lighter port fuse had blown and I replaced it, causing the radio to start working again.

I've checked all the fuses that I know I could and I have not seen any more blown fuses but there definitely could be. Everything ran fine when I left the driveway, but it was on the way back from my girlfriends work when the engine suddenly died.


Does anyone at all know what this possibly could be? I've heard that a relay could be bad, My starter could be bad, my alternator could be bad, a loose ground?

Could this be the cause of poor wiring? The wiring in this van is very shoddy, I bought it 2 years ago from a man who know just as little about vehicles as me. The wiring in this van is a hack job at best. There's all sorts of brakemaster and add-ons I have no clue what they do near my fuse box and a jumble of cables that have been mostly spliced and held together by clamp solders.

Thank you to anyone who sees this and responds. I appreciate you're time and help. I know the bare minimum about vehicles but I'm always happy to learn!
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Wednesday, August 24th, 2022 AT 2:18 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Hi,

It sounds like the engine locked up. If you take a breaker bar and socket to the crank pulley, are you able to turn the engine by hand?

Let me know.

Joe
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Wednesday, August 24th, 2022 AT 7:56 PM
Tiny
BRANDONLANGLOIS
  • MEMBER
  • 2 POSTS
When turning the crank pulley, should the van be put into neutral? Or left in park? Attached is a video of trying to start the van.
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Thursday, August 25th, 2022 AT 12:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Hi,

I hear the starter Bendix engage, so that tells me the circuit is working. With that in mind, either we have a loose or corroded battery terminal, faulty ground, or the starter motor has failed.

As far as checking if it is seized, you can have it in any gear to do it. Leave it in park to be safe.

If the engine turns by hand, I need you to perform one more test. On the starter motor itself, there will be a heavy gauge black wire which is direct power from the battery and a smaller gauge purple wire.

The black wire will always have power with the battery connected. The purple wire is different. It will only get 12v when the key is in the start position. So, if the engine isn't locked, all cables are tight, the battery is good, and you do get power to the purple wire, then the starter itself is likely the issue.

I attached the wiring schematic of the starter circuit below, so you have a reference.

Let me know what you find or if I can help.

Take care,

Joe

see pics below. Note: I had to cut the schematic in two, so it is readable for you. The two pics below are overlapped so you can follow from one to the next.
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Thursday, August 25th, 2022 AT 6:20 PM

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