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Super Mechanic
Super Mechanic, Master technician
Category: Chevy
Satisfied Customers: 16835
Experience:  29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering
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1988 chevy g20: van with 5.7 350 auto trans..rough..torque converter

Customer Question

1988 chevy g20 van with 5.7 350 auto trans... is starting rough and slow but still starting....has been like this for a few weeks. Battery is good (NEW) and replaced generator a year ago as well as starter is new about a year now. Could this be related to torque converter? Also, i noticed (prob. unrelated) that at idle the lower portion of the belt appears to have 1/2 inch of play up and down...could this be tensioner needs replacement?
Submitted: 5 years ago.
Category: Chevy
Expert:  Super Mechanic replied 5 years ago.

Hello and welcome to Just, Super mechanic here. About your vehicle.

The belt is self tensioning, (as you know) and there aren't any specs on it and they do seem to "bounce" a lot when the engine is running. The serpentine belt would make a alot of noise before it would slip enough to cause a charging problem.

From what it sounds like, the ignition timing could just be off some. I normally will unplug the wire at the distributor and see how it cranks. There is what is called a starter draw test, which will be very high when it is draging when starting, (like a LOL, it's hard to translate.

However, if the battery cables have too high a resistence it will do the same thing, like a bad starter. If you can, you may want to do a voltage drop test on them. HERE is a link to a video that covers voltage drop testing.

Super Mechanic and other Chevy Specialists are ready to help you
Customer: replied 5 years ago.
I have not personally had time yet (too busy working) to check into what you said to do, but my wife just texted me and said she heard a "chunking bang" when she left her friends house. She is now afraid to drive it. I told her get it home and I will check it out. Any other ideas? Can it be a misaligned starter? It never really seemed to me like a timing issue at all, rather possibly something binding up. Any other ideas?
Expert:  Super Mechanic replied 5 years ago.
I have had some starters that were too close to the flywheel and they would also drag and sometimes kick, but that was when they were just replaced and needed to be shimmed.

Either way, if it were a mechanical problem in the engine, (bearings, pistons, etc.) OR if it were an electrical issue, the starter draw test would be the thing that would tell us.

It is a little concerning with the "chunking bang" though, I must say. Could it have possibly been a backfire? (which may also indicate a timing issue)
Customer: replied 5 years ago.
Well, I went out and bought a new starter just in case, then (since it's cooler at night than during day in Phoenix now) I decided to remove the starter. When I got down underneath after jacking up van and removing ground from battery, I found that the largest cable going to the starter (ground?) was loose and the nut was missing. I can't believe that was the cause of all of this. Wow. Thought you might want to know. Thanks.Oh, and it ran beautiful when I put a new 9/16th lock nut on it and tightened it up. I will continue to check that ever so often and if it loosens up again I will put some locktite on it.
Expert:  Super Mechanic replied 5 years ago.
Good job, glad to hear that was all it was. Thank you and come again, anytime.