Onan Generators with recommended Champion Spark Plugs

[DonTom]

A few days ago, while I was at my Auburn, CA house, I started my RV generator as we should ever few weeks or so and then use it under load, when not getting much use otherwise. Started right up but died in around ten minutes. No codes, just died. Would not restart. Cranked as well as ever. No trace of even a sound of starting.

I removed the Champion spark plug (which was quite new) and it was VERY wet with unburnt gasoline. So I dried and cleaned off the plug, put it back in, still no start, totally no trace of even sounding like it will start, cranked as fast as ever.

My very first thought was the cheap $40.00 carb for my Onan that several people warned me about.

But then I recall a good 45 years ago, I had an issue with my 1971 BMW motorcycle running only on one cylinder. was a fairly new Champion spark plug causing the problem. I have seen it happen a couple more times with (only) Champion Spark plugs over the years in the same bike. Not a real common problem, but has happened enough times for me to remember this issue.

So I decided to try a NIB Champion spark plug in the Genny. From the same set of four. Same batch, I assume.

So I try to start the genny. Starts up instantly! I then ran it for 2.5 hours that day and two more hours the next day as well. Ran perfectly! No trace of any issue, for a total of 4.5 hours. I am convinced the Champion spark plug was the issue, even though the one in there now is also the same type of Champion plug.

But Champion still has the same somewhat common (at least not rare) problem for 45 years?

It seems to be a rather random issue, can happen on a new plug or it can last longer than 100K miles. I have wondered if Champion plugs are more sensitive to vibration or something like that. Something must be occasionally breaking inside of them.

But this is the first time I had this issue with my Onan. I have had it happen several times on my 1971 BMW motorcycle over the years.

Have others here had the same problem with Champion spark plugs? In Genny's or elsewhere?

-Don- Reno, NV

 

[Arch Hoagland]

I'd suggest putting the suspected bad spark plug back in and see what happens.

I buy all my electrical items for all my vehicles at the dealer for those vehicles due to many counterfeit items everywhere. I even buy my oil filters at the respective dealer as I know there are a ton of counterfeit oil filters on the market.

I figure the dealer will have the real one instead of a counterfeit.

 

[DonTom]

I'd suggest putting the suspected bad spark plug back in and see what happens.

I buy all my electrical items for all my vehicles at the dealer for those vehicles due to many counterfeit items everywhere. I even buy my oil filters at the respective dealer as I know there are a ton of counterfeit oil filters on the market.

I figure the dealer will have the real one instead of a counterfeit.

First I have heard of such. Who is making these fakes? I would think it would be too expensive to make a good fake, with the boxes and labels and all.

I am totally convinced that first spark plug has an issue. Even if it did run (which I doubt) , I would then think it was an intermittent plug problem anyway and still junk that plug.

A 2nd plug giving a problem would be more convincing to me that the issue wasn't really the plug. But 4.5 hours split over two days with no trace of an issue is all the convincing I need that the problem is solved.

-Don- Reno, NV

 

[phil-t]

I buy all my electrical items for all my vehicles at the dealer for those vehicles due to many counterfeit items everywhere. I even buy my oil filters at the respective dealer as I know there are a ton of counterfeit oil filters on the market.

I figure the dealer will have the real one instead of a counterfeit.

You really think name brand items on Walmart or Home Depot or Auto Parts stores are "Fake", or can be "fake"? I just can't believe that.

I'll keep taking my chances, I'd say after my 60+ years of doing so I'm good with the big box stores and aftermarket supplies. Dealers get my business when I have no other choice.

 

[Mark_K5LXP]

In my travels, any time there's a spark issue that a new spark plug resolved was sometimes the plug, but usually not. When it was the plug it was due to fouling but that's usually a mixture or oil contamination issue that will soon render the next plug equally fouled. If the engine is otherwise sound but had a "bad" plug the issue was a weak spark, either a bad coil or shot wires. The engine can run and often just fine with a weak spark but the minute there's any excessive fuel due to getting flooded or a bit of blow by oil there's not enough fire to burn through, or maybe the current gets conducted down the wet carboned center insulator to the plug body instead of arcing across the gap. Coils are usually all or nothing but the wires especially will degrade over time, as the conductors in noise suppression wires are essentially a carbon impregnated string that over time eventually wears out. I find that the symptom usually presents itself most at idle and I've had new wires magically restore a glass smooth idle to what was previously a pretty ratty running engine. It's not the easiest thing to prove wire gone south, you end up replacing it and noticing the thing just runs better. That's been my experience anyway.

Mark B.
Albuquerque, NM

 

[Old_Crow]

I've run Champions in most of my vehicles(cars, trucks and bikes)for as long as I can remember. Only out and out plug failure(not caused by fuel or oil fouling of a worn motor)was a pair of platinum plugs I was running in a Triumph chopper I had back in the early 80's. The plugs were the correct ones for the Bonneville, but I was running generic 12v car coils instead of a stock setup and apparently they generated too hot of a spark. Burned the tips right off the plugs. Replaced the platinum plugs with normal copper cored Champions and never had another problem.
I wonder if you've got a coil that's headed south.

 

[DonTom]

The one surprising thing about the bad plug I removed is it did NOT look fouled at all. Looked much like a new plug but with the electrode very wet with gasoline. It looked lean, not rich. And the same on the 2nd try with the same plug after I dried and cleaned it and tried it again.

The plug obviously wasn't firing at all. Just getting more cleaned by gasoline when in the genny.

I didn't look at the plug I replaced it with as the genny couldn't now run any better than it is.

FWIW, I have only seen this issue with Champion plugs. Not a real common issue, but I am surprised nobody else here has had the problem over the years with Champions.

-Don- Reno, NV

 

[DonTom]

I'd suggest putting the suspected bad spark plug back in and see what happens.

While I didn't do that with my Genny, I have done it years ago with my BMW motorcycle. I reversed the two plugs and the problem went to the other cylinder, proving without any possible doubt the spark plug was the issue.

What I cannot remember if is the plug measured open or shorted when checked on an ohmmeter, but I do remember I used an ohmmeter on it and the problem was obvious when comparing to another good Champion plug.

I will check my old genny plug on an ohmmeter then I get back to Auburn, perhaps on Tuesday, and compare to a new one.

-Don- Reno, NV

 

[DonTom]

Spark plug problem is now confirmed!

Here are the facts:

The bad plug measures 238.2K ohms between the threaded part and the top of the plug (where the cap would go). A high resistance short, which can be much like a dead short to high voltage, low current as supplied to a spark plug from the ignition coil.

I took a good new plug out of the box and tested it the exact same way (and tested each a few times). As expected, the new plug measures infinite between the exact same points using the same ohmmeter and all. This can be repeated on each plug as many times as tested.

There can be no doubts now at all. And it is the same issue I had back in the 1970's & 1980's with a Champion N7Y spark plugs used in my BMW motorcycle. That is how I remembered to use an ohmmeter, because I could see the difference back then too, but I couldn't remember what the difference in ohms was from that many years back.

The only difference is the genny plug is a Champion RN14YC instead of a N7Y.

So Champion still has the exact same issue after around 50 years. Not a big common issue, but I have seen it at least three times before on my BMW motorcycle. As likley to happen at 50 miles as 100,000 miles. Very random problem. Why this happens, I have no clue. I only know it does happen and here is the proof:

-Don- Auburn, CA

 

[TheBar]

Nothing eats plugs faster than the old two stroke dirt bikes. Champion plugs never lasted as long as others like NGK. I surmised that the resistor and non-resistor Champion plugs are the same to keep their mfg costs down. But in a car or truck engine Champion plugs are fine because the ignition is built for resistor plugs. I have seen gas fouling kill any brand of plug. I think it must form a varnish that conducts electricity. Maybe down in the deep recess around the center electrode. Can't see it but the plug will never fire right again.

 

[DonTom]

. I think it must form a varnish that conducts electricity.

What ever the issue is, I have ONLY seen it with Champion plugs and no others at all. And I have owned more vehicles than I could ever count.

FWIW, it will not stop me from using Champions, but if I am using Champions I will have spares and the tools to replace the plugs with me. Just as I do for my Genny.

But I did not expect to see this issue again after so many years. But I am now convinced the issue is still there with Champions and if my genny ever dies again the spark plug will be the first thing I check. Even if the generator time on the plug is only five minutes.

I recall once, many years ago, replacing old Champions on my BMW just because of the miles, they both worked perfectly. I put in new plugs, worked at first, but by the end of that day I was running on one cylinder as one of those new Champions crapped out. That was when I realized this problem can show up even on new Champion plugs.

-Don- Auburn, CA

 

[DonTom]

One thing I want to add here. When these Champions fail in this way, they are totally dead from that second on. My Champion plug failures have NEVER been intermittent. Will give NO trace of trying to start when they once fail in this way. A lot easier to notice in a single cylinder such as my Genny.

The BMW would still start on the opposite cylinder, but it was obvious that one plug was doing nothing at all.

AFAIK, Onan only recommends Champion plugs. So if your single cylinder (older RV gennys are often two cylinders) Onan ever dies with no codes at all and gives no trace of wanting to restart, do not panic, just replace the Champion spark plug.

-Don- Auburn, CA

 

[jubileee]

I have seen about a dozen or so Champion plugs fail in the manner you described over the last 60 years or so. There was an article I believe in Popular Mechanics in the sixties discussing the problem.
I’ve never seen the problem in other brands.

 

[DonTom]

I have seen about a dozen or so Champion plugs fail in the manner you described over the last 60 years or so. There was an article I believe in Popular Mechanics in the sixties discussing the problem.
I’ve never seen the problem in other brands.

I figured at least some others here must have seen this problem before.

What did Popular Mechanics say was the cause? My guess has been vibration causing something to break inside the plug. I have never seen the problem in any of my cars that had Champions, so I assumed it was related to vibrations as an old 2 cylinder motorcycle or single cylinder genny would have.

But discussed in Popular Mechanics during the sixties and still not fixed?

-Don- Auburn, CA

 

[phil-t]

Thanks for the comments on chapion plugs. It's been a very long time but I recall having issues with Champion plugs in my old Rotax single cylinder snowmobiles. Now it makes more sense. We would run NGK plugs to get away from that problem.

 

[Smokey613]

I replaced the plugs in both of my Ryobi 1800 inverter generators with NGK which btw, was recommended in the manual. They start even easier than they did when new.

 

[TheBar]

I've been the mechanic for a dozen family and friends for decades. Copper core plugs are actually higher performance and run cooler than platinum or iridium. Replace platinum or iridium plugs with copper core and they start easier, run smoother, and get better gas mileage. I've had copper plugs typically last 50K+ miles.

Regardless of mileage plugs need to be changed every 5 years or so to keep them from rusting or corroding especially on aluminum heads. Always use dialectic grease inside the boots and anti-seize lube on the threads.

 

[DonTom]

anti-seize lube on the threads.

Usually not these days. See here for why.

Read about "‘trivalent plating’" which I believe is used on all new spark plugs these days.

-Don- Auburn, CA

 

[TheBar]

I agree when directions are not followed anti seize is a liability. But the only problems from using anti seize is not reducing the torque by 20% or using way too much.

Yes, spark plugs have had a special coating for 20 years and it has been a highly debated topic for 20 years. But in the last 10 years have you taken out a factory installed high mileage plug after it has been in the head for 5+ years? That "special coating" is long gone and it takes twice the torque to remove the plug. That is when the threads strip. Use anti seize and they come out easy. Like so many things I consider "special coating" is mostly manufacturing hype to sell plugs to mechanics who like leaving out the coating step. Many people trade vehicles before the plugs get changed again so they never know. Personally I do all I can to protect the head.

 

[CharlesinGA]

Champion plugs......... gave up on them 40 years ago. They tended to recommend too cold of a heat range for the vehicle, they foul quickly......... buy more plugs.........

Nowdays I use just what the manufacturer recommends. One or two exceptions, but on something like this, I would use the Onan plug.

Antiseize on threads. Just go sparingly on it, don't get it on the bottom thread or two, and as mentioned, keep the torque to the minimum or less. I actually will remove plugs needlessly just to keep them broken loose. I have several antiseize products, but mostly use the 2500°F nickel neverseize that we used on jet engines.

There are lots of counterfeit parts on the market nowdays, Do some Google searches for Counterfeit auto parts and see what you get. Stay away from anything but known large company sources and even then stuff slips in once in a while.

Charles