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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: low budget on October 11, 2010, 09:56:29 pm
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My van is going through cap and rotors like crazy,[2per year]. It feels like it is missing real bad, but not all the time. I replace cap and rotor and it runs fine for awhile. My wife is a stay at home mom, and the van don't get that many miles per day. I Goggled it and found someone with the same problem. They said that it was "arc over" ??? that was causing it. It never said how to fix it. I have never heard of this and thought I would check and see if anybody has an ideas as how to fix it. Thanks in advance for your help!!!
1997 Chevy Astro
4.3L V6
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as your rotor turns under your cap-you would experience "arc over" when your dist. fires to an incorrect electrode-either ahead or behind the correct electrode.
I'm not too familiar with you ignition system but here are some of my thoughts
At what rpm is the miss? above say 3,000?
any DTC's?
Is it worse during or after rain?
moisture in the cap?
for now
test resistance on you ignition coil.
You could also unplug your crankshaft sensor (located at the front bottom of your engine) and check to see if it corroded. (because of the location) clean it and plug it back in.
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Could also be slop in the distributor causing it to flop all around and causing the rotor to strike the cap and then letting the spark to go were ever it wants.
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When I put a new set on, it runs great for a while, then all of a sudden it starts acting up again.
I talked to a guy today that said there are vent holes in the bottom of the distributor. Over time they plug up and that is what is causing my trouble. He said to drill a small in the bottom to act as a vent hole and put a tube in it to let it vent. He said that I'm building up moisture and that is what is causing my trouble. Sounds right to me because it is worse when it is raining/damp outside. It runs pretty good when it has been dry for a while. I think that is what I'm going to try first. Thanks for the info that was gave, I really do appreciate your time...
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Moisture would case a miss not the cap and rotor to be damaged. The weep holes could be clogged from metal shavings from the contacts on the cap and rotor
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That is exactly what he said. I'm going to try the vent hole and see what happens...
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While your at of see if there is any play in the distributor shaft
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here's a trick...
spray WD40 inside the cap. If it is indeed a moisture problem, the WD40 will clear it up temporarily since WD40 does not conduct electricity...it will focus the spark where it needs to go if there is a little moisture in the cap.
In other words, if it runs rough, spray WD40 and see if it smoothes it out. If so, it is indeed a moisture problem.
I remember one day way back when when my mustang (with the front ford distributors) stalled when it was in the middle of a downpour. I sprayed WD40 in the cap and put the cap back on and she ran great.
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Silly ford ;D
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I will be working on it tomorrow after work. My wife said it was real bad today, cool this morning and foggy.
Sarge, thanks for the trick, I'll see how it is running tomorrow and do that first.
While your at of see if there is any play in the distributor shaft
There has been no slop in the shaft before, but I'll check when I pull it apart...
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moisture would cause this condition
"as your rotor turns under your cap-you would experience "arc over" when your dist. fires to an incorrect electrode-either ahead or behind the correct electrode."
Moisture would case a miss not the cap and rotor to be damaged. The weep holes could be clogged from metal shavings from the contacts on the cap and rotor
this condition could cause arcing and burning of the contacts as the spark may not generally travel to the correct part of the elctrode causing premature failure.
I think you are definetly on the right track.
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I was under the impression that his cap was getting chewed up