Spark plugs?

I've never had an engine issue that was resolved by a fresh spark plug. Do these things actually wear out?

 

On older powersport machines I definitely have, dirtbikes and snowmobiles particularly. I would often foul plugs and need to clean or replace them.

However with newer 2 stroke engines, everything from snowmobiles to chainsaws being electronically controlled there is WAY less of an issue with fouling plugs than there used to be. I can ride thousands of miles on snowmobiles now without changing plugs, and I have yet to change a plug in any of my chainsaws.

It definitely happens on older 2 strokes though for sure.

 

It’s one of those things I used to change out every year on my small engines for cheap insurance. But I stopped doing it several years ago because it was so rare one ever failed. I did have a 21 Troy-Bilt mower that had one go bad. And on old equipment I’ve picked up to repair, they are sometimes bad. But in cars, definitely change them on the suggested schedule. They will go bad eventually and it’s better to do them on your schedule rather than when Murphy’s Law says so. Because you know that will be the worst timing possible.

An acquaintance of mine was just telling me last week how he decided to change his spark plugs in his vehicle. They were only 44,000 miles overdue! Surprise! The car runs better than it has in years.


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I'm asking because I am having an issue on my 1974, one cylinder, 4 stroke Kohler engine. The typical issue is fuel, carb, etc. But I couldn't get it to fire up today. Left me stranded.

 

Sometimes the insulator inside the plug can break down. You would never know by looking at it.

 

Yes they absolutely do wear out! I'll try to find the pics of the plugs I took out of my Tundra a while back. I got a CEL and a noticeable misfire. Having not done a tune up in a while. I changed plugs (along with some other stuff). The electrode was wearing out and the gap was huge!

 

Had an old points and condenser .028 Stihl that I bought new. Ran forever then one day just quit dead. I took it in and among other fixes, they showed me the spark plug with zero of the hook electrode remaining. Between electrode erosion and possible ceramic insulator damage, yes, they go bad. On the Kohler, if a new plug doesn't fix it, also check the plug wire for cracks and damage.

 

They definitely do wear out, it doesn't matter if it's new or or an old engine. The newer tech dues make better, longer lasting plugs, but yes, they certainly do wear out.

 

That’s exactly what happened to me with the mower I mentioned earlier. I was running perfectly the previous time I had used it. The plug was also less than a year old. I was ready to just put the thing on the side of the road when my wife said, “why don’t you just throw a plug it and see what happens”. I was shocked when the thing came right to life. My wife is good like that. When I begin to head towards the irrational side of things, she can usually pull me back.


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Absolutely, just had a bad one on my woodsplitter, 25hp twin.
Was splitting along and poppy pop pop, only hitting on 1 cly. Replaced pair next day ran like new. Only 160 hrs. On them, never been a fan of champions.

 

Hahaha...Everytime some piece of equipment won't start the first thing my wife says "does it have oil in it??"...Not sure why, but it pi$$es me off every single time!

 

Champions suck. If they are where in any new equipment I buy, I'll run it for a year then swap to a better brand. If it's used equipment, and has a champion it it, I'll change that out ASAP. That brand has left me high and dry/SOL a few times. Junk.

 

Your wife's comment would've saved my then ~35 year old Briggs 5 hp splitter engine. Guess who didn't check? Guess what happened on an oil burning old engine? $100 and a harbor freight run later, the chonda made that splitter so much better, so it was worth it in the end. The chonda has a low oil cutoff switch too.

 

Dead Rhino
tl;dr; Sparkplug replacement saved the day.

 

They do wear out, but it seems they have a long life span today. I remember changing them constantly on old snowmobiles-every one carried a handful in the glove box. Same thing with dirt bikes, and my father had a bunch in chainsaw box.
I have a pressure washer that is 15 years, a generator that is 10 years old, and an ATV that's 16 years old. I've never changed a plug on any of them!

 

I think that's mostly due to much better oil for 2 strokes than there used to be. Combo that with better plugs, more efficient fuel delivery via better carbs or precise EFI, that oil injected 2 strokes, these things all make plugs less likely to fail.
16 yrs on an ATV plug? You should probably change that. Unless you feel like risking a walk.

 

It's been awhile since leaded gasoline went off the market, but that was a major cause of plug failure. My old Champion Spark Plug tester and sand blaster fixed many a plug in it's day.

 

I’ve seen plugs die in my MS-250, snowmobiles, countless lawnmowers and just recently the JD farm tractor. It happens.
Once put a fresh set of plugs in my girlfriends ford escort. Bought at NAPA. Car ran fine but after my little tuneup it ran like crap. Not knowing what to do I set up an appointment at the Ford dealer. Told the guy on the phone the new parts I put in. Right off the bat he said replace the plugs, car won’t run on anything but Ford Plugs.
Thought he was nuts but I brought home 4 new plugs, swapped them out and it purred like a kitten. Still makes no sense to me too this day but it happened.

 

I had a 1985 GMC S-15 4 cylinder. I replaced the plugs just because I thought it was time. A couple weeks later it started running like crap. I thought I had gotten some bad gas. Added dry gas and ran with no improvement. I had the hood lifted with the engine running and kept hearing snap, snap. Spark was running down outside of one plug. I fished one of the old plugs out of the trash and replaced the defective new one. Ran great.

 

We have one of those Predators on my sons go kart. When he takes a left hand turn too hard, like when he is doing donuts, the engine stalls. I figure it is due to the low oil shut off.


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