Spark arc

[lostmarbles]

... I could see blue sparking arcing between the ends of all 6 spark plug boots, across the ceramic of the plugs and to the base of the plug/engine block......

I've just reread your first post and the above sentence suggests to me that you really have a plug/cap issue rather than an issue with your leads.

So I now agree with the advice on cleaning the plugs and caps.

But perhaps replacing the plugs with new ones of a good brand (like NGK) would be better than cleaning them. (Maybe they are from a "bad batch" and have an extra-high resistance that is encouraging the spark to travel outside?)

 

[vk7ybi]

The Bosch leads seem to be pretty good.. They have a good tight seal.. I've had water all over my engine and its not missed a beat..

 

[malcb]

Mate and I had this same trouble in a Datsun Patrol, misty/foggy weather it wouldnt run.. CRC fixed it enough to dry it out and get it going..

Seen that in a costal area, salt on the leads made then very prone to tracking when at all damp, also happens on old Mini's in the UK, dizzy is right behind radiator and in winter the salt on the roads gets everywhere.

There was a rubber cover avaliable at one time for the dizzy and I have seen a rubber glove used - been looking for a seven fingered glove for years.

 

[Coolerman]

IDave, just get rid of the Super Giga-Volt Flame throwing coil guaranteed to arc under water, and call it good.

 

[IDave]

I've just reread your first post and the above sentence suggests to me that you really have a plug/cap issue rather than an issue with your leads.

So I now agree with the advice on cleaning the plugs and caps.

But perhaps replacing the plugs with new ones of a good brand (like NGK) would be better than cleaning them. (Maybe they are from a "bad batch" and have an extra-high resistance that is encouraging the spark to travel outside?)

Nippon Denso plugs from a nice red box with "Toyota" printed on it aren't good plugs? I am planning on replacing them, with the same plug though.

Now that we're talking about it, I recall a discussion (maybe in the FJ45 section) about what the original plug was, and perhaps the current (pun intended) fit is different.

I'm going to go find that discussion now and link it...

*edit*

https://forum.ih8mud.com/fj45-owners-club/48021-spark-plug-66-f-fj45lwb.html

Bottom line is, there are choices for replacement ND plugs: WP16FSU (which is what SOR sells for this use) or W16PU. I've been using the W16FSU. Maybe I'll try the W16PUs this time.

 

[lostmarbles]

Nippon Denso plugs from a nice red box with "Toyota" printed on it aren't good plugs? I am planning on replacing them, with the same plug though.

Now that we're talking about it, I recall a discussion (maybe in the FJ45 section) about what the original plug was, and perhaps the current (pun intended) fit is different.

I'm going to go find that discussion now and link it...

*edit*

https://forum.ih8mud.com/fj45-owners-club/48021-spark-plug-66-f-fj45lwb.html

Bottom line is, there are choices for replacement ND plugs: WP16FSU (which is what SOR sells for this use) or W16PU. I've been using the W16FSU. Maybe I'll try the W16PUs this time.

I just gave NGK as an example of a "quality plug".

From what you say, I can see that you do indeed already buy quality plugs. (ND is "quality".)

So I think you're doing the right thing so long as your new "quality plugs" aren't from the same batch as the arcing ones. (In other words - Aren't bought from the same dealer around the same time as the originals.)

Then if the problem persists with your replacement plugs - I think you can rule out the plugs as being the cause.

As far as changing the plug model - Perhaps others should post up what they run. (My forty is a diesel of course so I can't advise about this - And my other advice is all based on experience with vehicles other than cruisers.)

 

[IDave]

I just gave NGK as an example of a "quality plug".

From what you say, I can see that you do indeed already buy quality plugs. (ND is "quality".)...

I thought they'd be acceptable! Although I will be switching from the W16FSU (1/2" protrusion into the head) from the W16PU (3/8" protrusion), I really can't see it being the plugs.

Cleaned the plug insulators, boots and wires with rubbing alcohol this afternoon. I'll have to wait until dark to see if that affects the arcing. Conductive dirt makes sense, since the spark almost has to be traveling from the wire along the inside of the boot (where it covers the ceramic insulator of the plug) along the uncovered portion of the plug insulator to the block/base of the plug.

 

[IDave]

St. Elmo's Fire

OK, well.

I cleaned up plugs and wires, checked gap as I mentioned and again, I got the arcing along the insulators of all 6 plugs. No arcing of the wires, cap, etc. It's been dry, low humidity this week.

So then, as many recommended, I replaced the rotor, cap and wires, all OEM stuff. Same result.

Then, I replaced the plugs with new Densos, 1/2 inch reach guys identical to what was in there. Same arcing.

Tonight I replaced with yet another set of plugs, this time Densos with the 3/8 inch reach. And, same.


I've not coated the insulators with dielectric grease. I mean to get some.


Haven't yet replaced the distributor condenser. Someone suggested that to me, and I guess I could try it. No easy way to test the old one. It's beyond my understanding just how that would affect it: maybe someone can explain?

Beyond that, I'm out of ideas. Obviously, there's more resistance inside the plugs (any plugs I've tried, anyway) than outside the plugs, or it wouldn't arc.

I'm sure open to suggestions if anyone can come up with something!!

 

[bsmith123]

condensor

Well the condensor is wired into the primary wiring. When the field collapses and induces voltage in the secondary windings it also induces in the primary and this can arc and pit the points. It's purpose is to extend point life



This might sound crazy but try ohming your installed spark plugs to the block and post up the resistance---Ill check mine---then pull the plugs and clean the holes --I am just toying with the plugs being high resist to ground and the spark finding an easier path

 

[IDave]

This might sound crazy but try ohming your installed spark plugs to the block and post up the resistance---Ill check mine---then pull the plugs and clean the holes --I am just toying with the plugs being high resist to ground and the spark finding an easier path

OK, maybe it is crazy, but I did it anyway.

Between the tip of the plug and the block I got complete resistance, and between the base of the plug and the block I got floating numbers, but essentially less than 1 (or 3) ohms, or no resistance (I tried 2 different meters).

The new plugs had virtually no resistance between the tip and the inner electrode.

I hope I'm doing what you had intended, because I'm flailing here!

 

[bsmith123]

checks

Between the tip of the plug and the block I got complete resistance

yup---thats insulated and goes to the tip

The new plugs had virtually no resistance between the tip and the inner electrode.

yup-the voltage travels from the tip to the inner electrode

between the base of the plug and the block I got floating numbers, but essentially less than 1 (or 3) ohms, or no resistance (I tried 2 different meters).

This is where I was hoping to find high resistance---I checked with my cheap meter and it pegged at less than 10 ohms but I will check with the fluke tomorrow


are all of the plugs doing it?

I would think that a big metal to metal contact like that should read basically no resistance ---I read mine to battery negative
that checks the ground from the engine too

 

[lostmarbles]

I don't really know what I'm talking about here - but could a faulty "ballast resistor" (or missing "ballast resistor") cause this?

It is just that I've read about them here before (on this forum) and they apparently drop the voltage to the coil.

So me thinks................ if one is missing or faulty (low resistance) - wouldn't this cause your problem iDave? - Too strong a spark that is!!!!!!

 

[vk7ybi]

One of my 40s had a Bosch GT40R coil in there.. Its designed for use with a ballast resistor.. I ran it for a long time without one, ran well but kept burning points.. If I pulled the coil lead from the distributor cap, I could make the spark jump about an inch.. I never had any strange arcing problems.. I dont think the ballast is the problem.. If a resistor goes bad, usually it will go open circuit or higher resistance, this would decrease current in the primary circuit, and therefore voltage in the secondary circuit.

The reason the GT40R coil got put in there was because the original had failed.. The coil would produce a spark in an air gap outside the engine, but wasnt strong enough to ignite the compressed mixture inside the cylinder..

 

[Coolerman]

Remember, a NEW spark plug wire has thousands of ohms resistance. The limit for Toyota wires of the period was 25,000 ohms.

Dave are your wires resistor type wires or racing wires? Measure one of them to see what it's resistance is.

What is your battery voltage at idle? At 2000 RPM? Notice your head lights are brighter? Maybe your regulator is allowing the alternator voltage to get above normal increasing the spark energy.

The ballast resistor not being in the circuit could cause this also. Maybe the starter bypass contacts got stuck and the ballast is now bypassed all the time...

Does the coil appear to get really hot after driving for a while?

 

[IDave]

[*]are all of the plugs doing it?

Yep. all and equally bright yellow white. It takes 30-45 seconds to start happening if the engine, plugs are cold...

"ballast resistor" (or missing "ballast resistor")

Too strong a spark....

I have things set up exactly the same as my FJ40 (doesn't do this) with the coil with the internal ballast resistor. So, it isn't missing. As far as functioning?

Yes, the too strong of spark thought did come up. Wouldn't that be limited by the condenser? And then, maybe I should be checking that out.

...ballast resistor.. I ran it for a long time without one, ran well but kept burning points.. If I pulled the coil lead from the distributor cap, I could make the spark jump about an inch.. I never had any strange arcing problems.. I dont think the ballast is the problem..

Sound's like that's unlikely then. Thanks.

Remember, a NEW spark plug wire has thousands of ohms resistance. The limit for Toyota wires of the period was 25,000 ohms.

Dave are your wires resistor type wires or racing wires? Measure one of them to see what it's resistance is.

What is your battery voltage at idle? At 2000 RPM? Notice your head lights are brighter? Maybe your regulator is allowing the alternator voltage to get above normal increasing the spark energy.

The ballast resistor not being in the circuit could cause this also. Maybe the starter bypass contacts got stuck and the ballast is now bypassed all the time...

Does the coil appear to get really hot after driving for a while?

The wires are the wires that CDan and SOR sell for this application. 90019-21017, so I doubt they are racing wires, but ? I can certainly ohm them. But wouldn't too high resistance wires spark at the distributor cap, rather than at the plugs?

I'll check and see about the battery voltage. No, headlights seem the same.
But that's not bad, so it's worth a look!

No starter bypass in my setup. Internal ballast resistor. I'll palpate the coil, Marc! It's the regular old toyota internal resistor, not a Super Giga-Volt Flame throwing coil.

Thanks, guys. I certainly have some more things to look at!

 

[Coolerman]

This is really bizarre

Sure your not driving through some conductive dust somewhere? Coal? Uranium? Got any other strange 'glows'?

Current ALWAYS follows the path of least resistance. So for what ever reason the ceramic has become conductive enough to bypass the plug gap. Any chance there is a contaminate INSIDE the plug boot? Are these boots really long?

How did the plugs look when pulled? Maybe they can't fire in the cylinder causing this. Oil fouled? Super high compression?

 

[bsmith123]

condensor?

I am rethinking the condensor -I think it might be a longshot but what if a continuing surge in the primary windings might make a longer and hotter spark out of the secondary as well?


But it is the sudden loss of volts in the primary that induces the voltage so if it continued on because of a bad condensor then that would seem to lessen the secondary voltage

Unless this is delayed and you are getting a second hit when it jumps to ground across the points


ahhhhhhh you know what? just go ahead and try a condensor ha ha!

 

[IDave]

This is really bizarre

Sure your not driving through some conductive dust somewhere? Coal? Uranium? Got any other strange 'glows'?

Current ALWAYS follows the path of least resistance. So for what ever reason the ceramic has become conductive enough to bypass the plug gap. Any chance there is a contaminate INSIDE the plug boot? Are these boots really long?

How did the plugs look when pulled? Maybe they can't fire in the cylinder causing this. Oil fouled? Super high compression?

No dust, no glows. And the coil was just a normal warm coil.

How would the ceramic from 3 sets of 6 plugs become conductive? I mean, this is immediately after replacement (minutes) on the last set. That's not it. My wife thinks the lights around the plugs are pretty.

Both the old and new plug wires/boots were the same. Both contaminated from Toyota? I cleaned off with alcohol both boots and plugs and it made no difference. I don't think they're long. The end of the boot is about 3/4 inch from the base of the plug/block. Same plug wires as my 9/70 FJ40 F155, which doesn't do this.

When I pull the plugs, they look basically good. A little carbon because I am starting with a choked engine (rich, not lean, environment!), definitely not oil fouled. I can post a picture later.

There's some oil, mostly on the threads. Yes, the rings are worn and no the compression is not super high!

I got some silicone based dielectric grease that I'll swab on at lunch time. I expect it might work to block the issue, but I still don't understand where its coming from.

 

[Pin_Head]

Dave,
It can't be really arcing past the insulator, or the engine would misfire. High voltage electricity is strange stuff and HV will follow the path of least resistance to ground. If all the voltage was dissipated outside across the insulator, it wouldn't make a spark across the spark plug gap. Are you sure it is a spark and not the corona caused by ionized gas molecules. The corona is the spark like glow you see from a Tesla coil or a Van de Graf generator. This corona is related to the high frequency radio interference that ignitions make. Things that cut down on RF interference will stop this too, like:

1. Shielded plugs and plug wires. It is hard to find these. They are used in military vehicles to make them less easy to spot from miles away. Resistor type plug wires are the next best thing.

2. Don't overdo the voltage. Is the plug gap set to factory specs? Is the rotor/cap gap too large?

This really isn't a problem as long as it runs fine. As long as the plug sparks, you will get 100% of the energy that is possible from combustion. In the long run, it may lead to insulation breakdown and misfiring or unrelibility.

 

[IDave]

Charlie,

It doesn't misfire, runs smoothly now that I replaced the points. Changing cap and rotor with OEM replacements didn't affect this at all.

Plug gap is .035, which is factory spec for an F135 from what I can tell. Later manuals give a range of .031-.035 (.8-.9mm) and I've gone with the higher end. I realize these aren't the exact same plugs they made in 1964, and it was suggested that the newer plugs are resistor type, but I don't think this sparking is seen in older vehicles generally.

I have wondered about it being a corona. It is a yellow-white glow that seems to pulse and flash somewhat in a rhythm that I assume comes with the spin of the distributor.

But the thing that worries me that it is spark and not corona is, my FJ40, with exactly the same ignition components except for different Denso plugs, does not do this.