How can I tell if my distributor or CAM is bad on my Chevy?

Tiny
MCCWHO
  • MEMBER
  • CHEVROLET ASTRO
To make a very long story short. I have a 1989 Chevy Astro CS, a remanufactured 4.3 v6 (though I think the engine installer lied to me, but thats another story), with 93k miles. I tried to start it one day and it went boom, a very loud boom. It turned out the timing chain was bad. After replaceing it the timing was set and I drove it for one day then it died while I was dirving. It would not start back up. I had a repair shop look at it. They said the distributor was not set right, they pulled it and reset it to the correct position. Next day it drove fine one the way to work. After sitting all night I started it to go home ( it seemed a little harder to start that morning then the night before), drove it home. It ran for about 10 minutes then died again. Again the distributor had moved. Now it is just sitting waiting. Any ideas on how to determine if the drive gear is bad on the cam or if it is the distributor. The gear on the distributor looks a little shinny on the tips but the cam gear does also. It is hard to see down the distributor hole, ?
Wednesday, July 25th, 2007 AT 1:53 AM

5 Replies

Tiny
MCCWHO
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  • 5 POSTS
Thats the problem. The distributor will not stay in mechanical time with the engine. When the distributor is pulled and set to the correct mechanical timeing, the engine runs for a short period of time then quits because the distributor has moved out of time.
I will check the pin that holds the gear on the distributor, just to be sure. I didn't think to check that, but I think the repair shop should have checked it since that is what they do for a living. Since the distributor is not in the engine right now I can check the shear pin in the morning.
I will rely back tomorrow night.
Any other ideas or suggestions?
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Thursday, July 26th, 2007 AT 10:27 PM
Tiny
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Well that was a good guess. The roll pin for the gear on the distributor is broken but not completely. I fear that this is only part of the problem.
The gear moves back-and-forth some and up and down a little, but, I don't think it is enough to explain how the distributor was getting so far out of time with the pistons. Unless this small amount of play is just enough for the gears to slip.
Is this possible?
If I knew I would not need to ask.
What else do you think could be a problem?

Thanks for your help!
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Saturday, July 28th, 2007 AT 4:46 AM
Tiny
POET042005
  • MECHANIC
  • 134 POSTS
Hi there well I'm gonna tell ya that damaged pin has everything to do with why the timing is off it only needs to move a little for the timing to move out of correct timing. If it dose not move to far the car will still start but it may take a few trys.

This is a tough one because I am worried that your gears that the distributor intertwines with is damaged. If you have not already bought a new or used distributor, this is just a theory take a good flash light and try to look into the hole at the gears to see if you can tell weather or not the gears are damaged. The timing chain may have damaged something more then expected.

Hope this helps

Richard
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Monday, August 13th, 2007 AT 11:32 PM
Tiny
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Yea the pin is actually broke on one side but still hanging on, onthe other side. I plan to replace the pin and give it try this week, after I renew my AAA membership, in case I need it towed again. I looked at the gear inside the engine last summer, it is really hard to see in there, as far as I could tell it looked ok. I even checked at the dealer to see if the gear is integrated with the cam or is held in place with a shear pin. They said it is forged as part of the cam and the only way it could be lose is if the cam is broke. Since the engine runs, then this is not the issue. So all thats left is the pin for the distributor gear.

I will reply back when I have had a chance to try it latter this week.
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Tuesday, August 14th, 2007 AT 10:38 PM
Tiny
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Been busy lately haven't had a chace to work on it until today. Got the pin replaced. Size and length are critical ( according to the dealer) but when I look down the hole I don't see any thing that the pin could have hit if it were a 1/16 of an inch longer. So I could have saved $5.00 and bought it from an After market parts store. Dealers are sometimes out to get ya.
Any way got it all togather today, and it is now mechanically in time. I will reply back latter with the results after I have had a chance to drive it around a little to see if that fixed the issue.

Special thanks to all who replied you saved me alot of stress and money Kudos to you all. :D
:D
Thanks :D :D
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Tuesday, October 16th, 2007 AT 12:32 AM

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