ratcheting noise from distributor | need help to chase the arcs

[ikeepmychevytoo]

...well, I discovered this noise from distributor, like a modern injector noise. A continious but very subdued sound, you need to lean towards the cap with an ear to notice it. I guess there is an arc patern inside it. Previously I had started to feel something like a misfire at high speeds, so the flash striked and I think I really have a misfire problem. There used to be an occasional arc from a cable to the oil-stick tube, I solved it with better insulation to only move it to distributor

Runs very peppy at lower speeds. Cap is relatively new, inside is clean, no carbons. Dew? I sprayed wd40 many miles ago (could this be the problem?) I'm going to replace the spark plugs, wires, ignition module, the coil and will hope it to go away (eventhough many checks ok). So, to be frank, I don't know what is really going on. If there is any insights, or experiences I'd highly appreciate it.

 

[brianl703]

Sometimes the bearings in the distributor wear out and allow excessive play in the distributor.

This can allow the parts inside the distributor to touch, perhaps resulting in noise.

On my brother's old car the distributor cap would occcasionally be damaged (broken terminals, cracked, etc) and I think this is what was happening.

 

[Dark Jedi]

if its making noise. jsut replace the cap and be done with it. but like said before. would be nice to know engine, make, year, yadda yadda yadda.

could start the engine at night and rev at the throttle linkage. and see if there are external arcs.

 

[CBR.worm]

I don't think i'd get my ear too close to those volts. . .

 

[ikeepmychevytoo]

Sorry guys, this is the first time I'm doing this mistake, my mind must have been off... '84 Chevrolet Celebrity with 2.8 GM and classical HEI ignition with separate coil (w/ Canadian emissions).

brian: I think it is not a mechanical noise. Checked recently for radial play. I will inspect inside the cap closer this time.

And yes, I scare from those 35k Volts. I'm taking the caution.

I guess the real problem is, why it finds a place to jump. I've fixed cable routing and now it is inside the cap after this. This is 20+ year-old system. I'll change everything, orders already arrived but since I don't know the original problem this may happen again so I fear to ruin new coil and module promptly again.

I recall some hints starting like "if rotor tongue has carbon tracking at the "leaving" corner...." but very old memory and I can't recall the rest. And yes, rotor is like this.

 

[cousincletus]

You may need a rebuilt distributor.

 

[MolaKule]

It would be nice if you guys gave us a clue as to what vehicle, year, etc, since some makes have specific problems for specific years.

We have many good mechanics here but their crystal balls only have a certain amount of psychic energy available.

 

[Tosh]

I think you have one bad plug wire.

 

[bruce381]

look at running motor at night with NO light the arcing if any maybe visible
bruce

 

[brianl703]

Does the distributor cap have a vent on it? Is this vent blocked?

According to what I have read, the vent is to allow ionized air to escape from the distributor cap, otherwise the ionized air will allow arcing.

 

[ikeepmychevytoo]

^ hmm... indeed it doesn't do it for the first couple of minutes. May be ionizing too much...I never heard this before, intersting... Will look at it... not a vent but bottom is kind of loose, there is a channel as if a seal should be there but no seal by design.

Thank you guys for the ideas so far... will check every of them. There "was" a visible arc. Checked last night sprayed water, and none visible. I bet it is inside the cap... may be I should get one of those fancy clear caps that I saw on pimp my ride

Interestingly, drivability doesn't suffer much. Just not as peppy at post60 mph speeds as before. At cruise I feel an occasional somewhat a misfire.

 

[Schmoe]

Had a similar problem with my 3.3 GM engine, but with coil packs instead. It was the wires, they just don't last long when exposed to all that heat after time.

 

[mechtech]

Usually, that noise in an HEI dist is from the coil spring or carbon tab being burned up or missing. Possibly a bad coil, too.

 

[andyd]

No clue with modern , new fangled 80s stuff.

Check the inside of the cap for carbon tracking between the terminals. This can cause a miss similar to wires cross firing. Usually it can be wiped off with the help of some brake cleaner if need be.

 

[ikeepmychevytoo]

As you may noticed what kills me is the curiosity, every mind stirring is valuable. Thank you all for the replies. Here's the observations so far...

I removed the plugs and inspected. Gaps haven't changed and looking normal with center two displaying a tad richer condition. I guess GM's gap spec of .045" is a bit too on the edge -may be this is so with the todays gas. I lowered the gaps to .040" and just put back. It is even better at the low-end now. New, identical spec. AC R 43 TS plugs look a little different with center electrode is protruding slightly farther. Interesting? Electrodes on two of them wasn't centered perfect, very obvious to the eye. I think of putting them to #2 and #5 igniting cylinders.

Indeed I've cleaned inside the cap. Which was clean to begin with. Now it looks like new. Eventhough plastic on rotor appears a little melted on the leaving side, the mark on the tabs were looking almost centered. So that's why I lowered the gaps. Either coil is slow (basic manual checks are OK), gaps are excessive, wires are bad, or the new module (semiconductor switch; replacement for the novel points) is bad. In fact this no go at high revs. started when the old module gone suddenly and I had to put this cheap one. Appears like a quality item but not original and costs 1/3 of the Delco.

So, appearantly I had a multiple problem. Slightly off topic but, within this spark plug re-gapping I've soaked cylinders with B 12 Chemtool, followed with an oil based cleaner and I've had a hard time to believe all those black chunks poured out from those cylinders! A handful at least. After this I got back the mid revs too, and engine is silent again... I was forgotten how quiet this car was. Interesting thing that the previous water, solvent, cleaner oil injections through the PCV did not do a thing so I was started to worry about the mechanicals for the knocking sound when hot. It completely gone. Did a water injection after again and the low revs. got slightly bad. I guess intake is full of carbons (as was the EGR ports), and once they find their way into the cylinders they can't get out from there easiliy no matter how loose they are.

 

[Mr Nice]

I thought that 'vent' on the cap was to prevent moisture from building up inside the cap.

 

[ikeepmychevytoo]

Thanks for all the replies. I've replaced plugs and cables, cap and rotor, coil and module. Haven't yet took for a spin. Noise is gone. Then I noticed idle was little high (mixture was rich). Whence I re-adjusted idle here we go again... similar sound. But much more subdued. Could this be dependant on mixture?

Interesting thing it wasn't/isn't doing this when stone cold. It does this after about three minutes of idle.

I noticed rotor to tabs clearance is about 1/5". So isn't the spark actually have to jump, and couldn't this noise considered normal?

How do I control the bearings? Lower portion lubricated from the engine and upper supposed to be lubed for life. Any way to tell if it is bad... I can't jiggle the rotor head one bit